Genetic characterization of foot-and-mouth disease viruses, Ethiopia, 1981-2007

Analysis of the immunological response elicited by a polyvalent foot and mouth disease vaccine and its compatibility with a diva test in Jimma Town, Ethiopia

The research was conducted in Jimma town, Oromiya Regional State, from October 2022 to June 2023, with the aim of assessing the immune response of polyvalent FMD (Foot and Mouth Disease) vaccine. The study involved 34 cattle in a longitudinal study, divided into two groups: 29 vaccinated and 5 unvaccinated. The vaccinated cattle received an inactivated polyvalent FMD virus vaccine produced by the National Veterinary Institute. Blood samples were collected on days 0, 14, 21, 35, 80, and 125 after vaccination and tested using Virus Neutralization Test and 3ABC ELISA. The results showed a significant increase in neutralizing antibodies against structural proteins in all vaccinated cattle on day 14 after vaccination for all three serotypes. (A/ETH/21/2000, p = 0.015; O/ETH/38/2005, p = 0.017; SAT2/ETH/64/2009, p = 0.007). On day, fourteen of post-vaccination vaccinated group showed immune response equal or above 1.5 log10 in a proportion of 69%, 73% and 94% for serotype A/ETH/21/2000, O/ETH/38/2005 and SAT2/ETH/64/2009 respectively. The status of raised antibody titer on day 125 post-vaccination showed decreasing by 14%, 18% and 4% for serotype A/ETH/21/2000, O/ETH/38/2005 and SAT2/ETH/64/2009 respectively. The DIVA test, or 3ABC ELISA, used to differentiate infected from vaccinated animals, revealed the absence of immune response to the Non-structural protein in the vaccinated cattle group. Conversely, the unvaccinated group showed no recorded antibody titer to both structural and non-structural proteins. In summary, the commercially available FMD vaccine, comprising serotype A, O, and SAT2, triggers an immune response to the structural protein rather than the non-structural protein after the initial administration. This outcome implies that FMD vaccines from the National Veterinary Institute align with the DIVA test. Nevertheless, additional efforts may be necessary to bolster the strength and duration of the vaccine-induced immune response.

Discovery, recognized antigenic structures, and evolution of cross-serotype broadly neutralizing antibodies from porcine B-cell repertoires against foot-and-mouth disease virus

It is a great challenge to isolate the broadly neutralizing antibodies (bnAbs) against foot-and-mouth disease virus (FMDV) due to its existence as seven distinct serotypes without cross-protection. Here, by vaccination of pig with FMDV serotypes O and A whole virus antigens, we obtained 10 bnAbs against serotypes O, A and/or Asia1 by dissecting 216 common clonotypes of two serotypes O and A specific porcine B-cell receptor (BCR) gene repertoires containing total 12720 B cell clones, indicating the induction of cross-serotype bnAbs after sequential vaccination with serotypes O and A antigens. The majority of porcine bnAbs (9/10) were derived from terminally differentiated B cells of different clonal lineages, which convergently targeted the conserved "RGDL" motif on structural protein VP1 of FMDV by mimicking receptor recognition to inhibit viral attachment to cells. Cryo-EM complex structures revealed that the other bnAb pOA-2 specifically targets a novel inter-pentamer antigen structure surrounding the viral three-fold axis, with a highly conserved determinant at residue 68 on VP2. This unique binding pattern enabled cross-serotype neutralization by destabilizing the viral particle. The evolutionary analysis of pOA-2 demonstrated its origin from an intermediate B-cell, emphasizing the crucial role of somatic hypermutations (SHMs) in balancing the breadth and potency of neutralization. However, excessive SHMs may deviate from the trajectory of broad neutralization. This study provides a strategy to uncover bnAbs against highly mutable pathogens and the cross-serotype antigenic structures to explore broadly protective FMDV vaccine.

Seroprevalence and risk factors of sheep and goat pox virus in selected districts of Wolaita Zone, Southern Ethiopia

IMPORTANCE

Sheep and goat pox (SGP) virus infection is a highly fatal viral infection of small ruminants that causes major production losses in sheep and goats in Ethiopia while also limiting international trade.

OBJECTIVE

This study aimed to estimate the seroprevalence of SGP infection and assess related risk variables.

METHODS

A cross-sectional study was conducted from February to August 2023 on 384 serum samples taken from sheep and goats. A serum neutralization test was conducted to detect the presence of antibodies against the SGP virus in Wolaita Sodo Regional Laboratory.

RESULTS

The overall seroprevalence rate of SGP was 4.95%. Factors such as sheep (8.26%), female sheep and goats (7.45%), older sheep and goats (8.33%), larger flock size of sheep and goats (10.47%), poorly conditioned sheep and goats (31.58%), sheep and goats with a tick on their skin (10.38%), and animals that had not been vaccinated (5.17%) were found to have higher seroprevalence. Furthermore, the seropositivity in sheep was five times greater than in goats (adjusted odds ratio [AOR], 4.73; 95% confidence interval [CI], 1.39-15.99). Additionally, large-sized flocks of sheep and goats were more likely to be seropositive to pox disease than small-sized flocks (AOR, 6.73; 95% CI, 1.58-28.67).

CONCLUSIONS AND RELEVANCE

Thus, the study revealed the prevalence of SGP in the Wolaita zone. Additional research should be conducted to estimate the extent of the disease at the regional level, and management measures should be implemented to reduce the economic losses associated with this condition.

Foot and mouth disease vaccine efficacy in Africa: a systematic review and meta-analysis

Background

Several factors, such as diverse serotypes, vaccination methods, weak biosecurity, and animal movements, contribute to recurrent Foot-and-Mouth Disease Virus (FMDV) outbreaks in Africa, establishing endemicity. These outbreaks cost over $2 billion annually, prompting a high-priority focus on FMDV vaccination. Despite extensive efforts, vaccine efficacy varies. This study aims to evaluate routine foot and mouth disease (FMD) vaccines in Africa via systematic review and meta-analysis.

Methods

A systematic review and meta-analysis were carried out following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Meta-analysis was conducted to assess the efficacy of FMDV vaccination using the meta for package of R.

Results

Vaccinated animals have roughly a 69.3% lower chance of FMDV infection compared to unvaccinated animals, as indicated by the pooled results from the random-effects model, which showed a risk ratio (RR) of 0.3073. There was a statistically significant heterogeneity (p < 0.05) across all of the included articles.

Conclusion

Overall findings suggest that if properly planned and implemented, FMDV vaccination programs and strategies in Africa could help control the spread of the disease throughout the continent and beyond.

Seroprevalence and molecular detection of foot and mouth disease virus in cattle in selected districts of Wolaita Zone, Southern Ethiopia

Foot and mouth disease (FMD) is a highly contagious, endemic, and acute viral cattle ailment that causes major economic damage in Ethiopia. Although several serotypes of the FMD virus have been detected in Ethiopia, there is no documented information about the disease's current serostatus and serotypes circulating in the Wolaita zone. Thus, from March to December 2022, a cross-sectional study was conducted to evaluate FMDV seroprevalence, molecular detection, and serotype identification in three Wolaita Zone sites. A multistage sample procedure was used to choose three peasant associations from each study region, namely Wolaita Sodo, Offa district, and Boloso sore district. A systematic random sampling technique was employed to pick 384 cattle from the population for the seroprevalence research, and 10 epithelial tissue samples were purposefully taken from outbreak individuals for molecular detection of FMDV. The sera were examined using 3ABC FMD NSP Competition ELISA to find antibodies against FMDV non-structural proteins, whereas epithelial tissue samples were analyzed for molecular detection using real-time RT-PCR, and sandwich ELISA was used to determine the circulating serotypes. A multivariable logistic regression model was used to evaluate the associated risk variables. The total seroprevalence of FMD in cattle was 46.88% (95% CI 41.86-51.88), with Wolaita Sodo Town having the highest seroprevalence (63.28%). As a consequence, multivariable logistic regression analysis revealed that animal age, herd size, and interaction with wildlife were all substantially related to FMD seroprevalence (p < 0.05). During molecular detection, only SAT-2 serotypes were found in 10 tissue samples. Thus, investigating FMD outbreaks and identifying serotypes and risk factors for seropositivity are critical steps in developing effective control and prevention strategies based on the kind of circulating serotype. Moreover, further research for animal species other than cattle was encouraged.

A review of foot-and-mouth disease in Ethiopia: epidemiological aspects, economic implications, and control strategies

Foot-and-mouth disease (FMD) is a contagious viral disease that affects the livelihoods and productivity of livestock farmers in endemic regions. It can infect various domestic and wild animals with cloven hooves and is caused by a virus belonging to the genus Aphthovirus and family Picornaviridae, which has seven different serotypes: A, O, C, SAT1, SAT2, SAT3, and Asia-1. This paper aims to provide a comprehensive overview of the molecular epidemiology, economic impact, diagnosis, and control measures of FMD in Ethiopia in comparison with the global situation. The genetic and antigenic diversity of FMD viruses requires a thorough understanding for developing and applying effective control strategies in endemic areas. FMD has direct and indirect economic consequences on animal production. In Ethiopia, FMD outbreaks have led to millions of USD losses due to the restriction or rejection of livestock products in the international market. Therefore, in endemic areas, disease control depends on vaccinations to prevent animals from developing clinical disease. However, in Ethiopia, due to the presence of diverse antigenic serotypes of FMD viruses, regular and extensive molecular investigation of new field isolates is necessary to perform vaccine-matching studies to evaluate the protective potential of the vaccine strain in the country.

Pathological and genetic characterization of foot and mouth disease viruses collected from cattle and water buffalo in Egypt

Foot-and-mouth disease (FMD), a highly contagious viral disease caused by FMD virus (FMDV) that threatens Egypt's livestock industry. FMDV causes severe economic losses in the livestock, with restriction of international trade from endemic regions. Surveillance for FMDV serotypes circulating in Egypt is urgently needed to assess the epidemiological situation in the country. FMD outbreaks reported in Egypt in between December 2016 and January-March 2017. A cross-sectional study was conducted to identify the FMDV serotypes responsible for the outbreaks and to collect information on the virus's morphopathological effects. Postmortem tissue and clinical samples (oral swabs, vesicular fluids from ruptured vesicles, and blood) were collected from recently deceased and infected animals. Pathological examination revealed classical FMD lesions as vesicular and erosive lesions on epithelial tissues with non-suppurative lymphoplasmacytic myocarditis. Phylogenetic and sequencing analyses demonstrated that FMDV serotype O, EA-3 topotype, VP1 is the prevalent serotype responsible for the pathological alterations and the high mortality in young calves, adult cattle, and water buffalo. The outcomes indicate continuous mutations in the circulating FMDV, which result in the occasional failure of vaccination. Based on these findings, extensive continuous monitoring and serotyping of the existing circulating FMDV isolates and regular vaccination with reevaluation of the currently used vaccine in Egypt are recommended to prevent the recurrence of such outbreaks.

Outbreak investigation of foot-and-mouth disease in cattle in Tigray region, Northern Ethiopia

An investigation of a foot-and-mouth disease (FMD) outbreak was conducted between late October and mid-December 2019 in Tigray region. The outbreak investigation team collected epidemiological data from the six villages of Kafta Humera and Seharti Samre districts, including morbidity proportions, mortality proportions, and clinical signs, and cattle management and vaccination history were collected via participatory methods, including interviews and group discussions with local experts and farmers in Kafta Humera and reports from the district veterinarians in Seharti Samre. Twenty-two tissue samples were collected for laboratory confirmation. Overall, 4,299/9,811 (43.8%) and 13,654/16,921 (80.6%) cattle showed clinical signs for FMD in Kafta Humera and Seharti Samre, respectively. In Kafta Humera, the highest morbidity proportion was found in adult cows and heifers (48.1%), followed by 27.8% in oxen and 15.9% in calves. In Seharti Samre, the morbidity proportion was similar in all age groups at ~81%. No death of FMD-suspected cattle was reported throughout the outbreak. The serotype of foot-and-mouth disease virus (FMDV) identified by laboratory analysis differed between the two districts (serotype O in Kafta Humera and serotype A in Seharti Samre). We, therefore, suggest that the outbreaks in the two districts occurred independently from each other. Experts and farmers were interviewed and believed that the outbreak in Kafta Humera was most likely caused by interaction between cattle and wildlife from the surrounding Kafta Sheraro National Park, which share common grazing land. This outbreak investigation showed that FMD can cause devastating cattle morbidity. A regular vaccination program against the identified circulating FMDV serotypes with sufficient coverage is required to avoid future outbreaks.

Humoral Immune Response in Calves Vaccinated with Monovalent Vaccines or a Trivalent Combination Thereof and Matching of These Vaccines to the Selected Circulating Foot-and-Mouth Disease Viruses in Ethiopia

Foot-and-mouth disease (FMD) is an endemic, highly contagious, and devastating disease of livestock production in Ethiopia. Control of this disease relies mainly on prophylactic vaccination by willing farmers without a countrywide vaccination program. The objectives of this study were to quantify the humoral immune response and evaluation of the serological relationship of the vaccine strain used with representative field strain isolates. This was performed by primo vaccination of 6-9-month-old Holstein Friesian calves (35 treatment and 4 control calves) on day one and booster vaccination on day 28. Calves were vaccinated using the locally available National Veterinary Institute (NVI), Bishoftu, Ethiopia, inactivated aluminum hydroxide adjuvant monovalent (either O, A, SAT-2 alone) or trivalent (combination of A, O, SAT-2) vaccine (A/ETH/6/2000 (G-VII, O/ETH/38/2005(EA-3) and SAT-2/ETH/64/2009(XIII)). A 2 mL or 4 mL dose was used to vaccinate all calves except the animals that served as a control. In the case of the trivalent vaccine, a 4 mL dose was used to vaccinate calves. The serum was collected at 7, 14, 21, 28, and 56 days post-vaccination (d.p.v.). The humoral immune response was quantified by the solid-phase competitive enzyme-linked immunosorbent assay (SPC ELISA) and the virus-neutralization test (VNT). The serological relationship of heterologous and homologous viruses was also evaluated by adjuvant vaccine matching tests. The r1-value was determined using serum collected 21 d.p.v. An increase in immune response was observed from 7 d.p.v. to 28 d.p.v. in calves who received a 4 mL dose containing a 107.24 antigen load of 100 tissue culture infective dose (100TCID50) virus titer in the formulation. Upon receiving a booster dose on day 28, the humoral immune response was checked on the 56th day post-initial vaccination. Amounts of 54%, 72%, 79%, and 72% of inhibition for A, O, SAT-2, and trivalent vaccine in the three serotypes SPCE, respectively, was measured. Here, it was found that the immune response of calves increased from day 7 to 56, as evidenced by SPCE analysis. Likewise, an increase in antibody titer measured by a one-dimensional virus neutralization assay was also in line with SPCE analysis. This indicates that the vaccine is capable of inducing a neutralizing antibody that confers a protective immune response in 70%, 62%, and 100% heterologous field strains of A, O, and SAT-2 isolates, respectively, and has an average antigenic relationship of >0.3 with a standard deviation of +0.05 (N = 3) to the vaccine strains A/ETH/6/2000, O/ETH/38/2005 and SAT-2/ETH/64/2009, respectively, when using the one-dimensional virus neutralization test. The contribution and importance of this study is a confirmation of the vaccine and the field strain serological relationship for serotype SAT-2 strain and further research/change of vaccination strategy/ improvement in the currently used vaccine to cover a wide range of prevailing genotypes/lineages and induction of sound immune response after vaccination for serotype A and O strain. This study suggests that the trivalent vaccine produced by the National Veterinary Institute containing viral isolates from serotype O, A, and SAT-2 has a good serological relationship with the majority of circulating field strains in Ethiopia.

A review of foot-and-mouth disease status and control measures in Botswana

Foot-and-mouth disease (FMD), an economically important disease of livestock, is endemic in Botswana. The country has been affected by this disease since the early 1930s, and FMD virus (FMDV) continues to circulate in both domestic and wild animal populations. Botswana is affected by the Southern African Territories (SAT1-3) of FMDV. Up to 80% of the income in the agricultural sector in Botswana is derived from the beef production, and about 70% of Botswana's beef exports go to the European Union (EU) market. Thus, trade restrictions caused by FMD outbreaks may result in declines in revenue. In this review, the FMD status of Botswana from 2006 to 2022 is discussed. During the report period, SAT2 was responsible for 80 out of a total of 87 FMD outbreaks, while SAT1 was responsible for 7 out of 87 outbreaks. These outbreaks were a result of SAT1 topotype I and SAT2 topotypes I, II, and III. There were no outbreaks associated with serotype SAT3 over the review span, suggesting absence of this serotype in the country, although it is still maintained in vaccines formulated for use in Botswana. Most of the outbreaks reported in this review occurred in the North West district of Botswana; an area that is heavily populated with cloven hooved wildlife. This highlights the role of wildlife-domestic animal interaction in FMD spread and maintenance. The Food and Agriculture Organization (FAO) of the United Nations has created a progressive control pathway for FMD (PCP-FMD) for the global elimination of FMD to reduce FMD-related losses. This review highlights how Botswana takes part in the PCP-FMD by putting in place control measures such as surveillance and vaccination. The review also touches on the disease control challenges such as limitations to separation of livestock with populations of buffaloes and lapses in livestock vaccination which contribute to maintenance of FMDV circulation in Botswana.

Viral Protein 1 (VP1) Sequence-Based Genetic Diversity of SAT 2 FMDV Circulating in Ethiopia from 1990 to 2015

Introduction

Pathogen molecular epidemiology determines the origin of specific outbreaks locality of foot-and-mouth disease virus serotype South African Territories-2 sequence-based analysis of highly variable Viral Protein 1 (VP1), which helps to identify the evolution of this virus through time and space. The objective of this study was to compare the differences between SAT-2 VP1 sequences of FMDV circulated in Ethiopia from 1990 to 2015 at the genetic level.

Methods

The nucleotide and amino acid sequences were analyzed using Basic Local Alignment Search Tools (BLAST), Multiple sequence alignment and sequence editing and Phylogenetic tree reconstruction. The nucleotide and amino acid sequences alignment, distance matrix, and phylogenetic tree constructions were done using the MEGA 6.0 software package.

Result and Discussion

In this analysis, we found 76% nucleotide identities and amino acid similarities among the sequences. The overall group mean distance at nucleotide level was 19% with a mean intra-population diversity of 2%. The lowest sequence variation was observed among sequences obtained from the years 2007/09/10, 2014/15, and 1990/91 which was less than 5% among them. This analysis revealed that in the last 25 years, four different topotypes of the FMDV SAT-2 were circulating in Ethiopia. The Arg-Gly-Asp (RGD) amino acid (AA) motif at AA position 144-146 within the G-H loop of the VP1 protein of FMDV is conserved, but up- and downstream hyper-variable AA sequences are identified. In this study, it was observed that four topotypes (IV, XIV, XIII, and VII) were circulating in Ethiopia for 25 years. Further, compared with sequences from neighboring countries (Sudan, Kenya) confirmed the presence of these topotypes.

Conclusion

Pertinent to this genetic diversity control strategies in Ethiopia should be based on having regular antigenic and genetic vaccine matching tests with the circulating strain within a defined period, space, transboundary nature of the disease and applying biosecurity measures.

Epidemiological Dynamics of Foot-and-Mouth Disease in the Horn of Africa: The Role of Virus Diversity and Animal Movement

The Horn of Africa is a large area of arid and semi-arid land, holding about 10% of the global and 40% of the entire African livestock population. The region's livestock production system is mainly extensive and pastoralist. It faces countless problems, such as a shortage of pastures and watering points, poor access to veterinary services, and multiple endemic diseases like foot-and-mouth disease (FMD). Foot-and-mouth disease is one of the most economically important livestock diseases worldwide and is endemic in most developing countries. Within Africa, five of the seven serotypes of the FMD virus (FMDV) are described, but serotype C is not circulating anymore, a burden unseen anywhere in the world. The enormous genetic diversity of FMDV is favored by an error-prone RNA-dependent RNA polymerase, intra-typic and inter-typic recombination, as well as the quasi-species nature of the virus. This paper describes the epidemiological dynamics of foot-and-mouth disease in the Horn of Africa with regard to the serotypes and topotypes distribution of FMDV, the livestock production systems practiced, animal movement, the role of wildlife, and the epidemiological complexity of FMD. Within this review, outbreak investigation data and serological studies confirm the endemicity of the disease in the Horn of Africa. Multiple topotypes of FMDV are described in the literature as circulating in the region, with further evolution of virus diversity predicted. A large susceptible livestock population and the presence of wild ungulates are described as complicating the epidemiology of the disease. Further, the husbandry practices and legal and illegal trading of livestock and their products, coupled with poor biosecurity practices, are also reported to impact the spread of FMDV within and between countries in the region. The porosity of borders for pastoralist herders fuels the unregulated transboundary livestock trade. There are no systematic control strategies in the region except for sporadic vaccination with locally produced vaccines, while literature indicates that effective control measures should also consider virus diversity, livestock movements/biosecurity, transboundary trade, and the reduction of contact with wild, susceptible ungulates.

B and T Cell Epitopes of the Incursionary Foot-and-Mouth Disease Virus Serotype SAT2 for Vaccine Development

Failure of cross-protection among interserotypes and intratypes of foot-and-mouth disease virus (FMDV) is a big threat to endemic countries and their prevention and control strategies. However, insights into practices relating to the development of a multi-epitope vaccine appear as a best alternative approach to alleviate the cross-protection-associated problems. In order to facilitate the development of such a vaccine design approach, identification and prediction of the antigenic B and T cell epitopes along with determining the level of immunogenicity are essential bioinformatics steps. These steps are well applied in Eurasian serotypes, but very rare in South African Territories (SAT) Types, particularly in serotype SAT2. For this reason, the available scattered immunogenic information on SAT2 epitopes needs to be organized and clearly understood. Therefore, in this review, we compiled relevant bioinformatic reports about B and T cell epitopes of the incursionary SAT2 FMDV and the promising experimental demonstrations of such designed and developed vaccines against this serotype.

Combined Adjuvant Formulations Enhanced an Immune Response of Trivalent Foot and Mouth Disease Vaccine in Cattle

Introduction

Foot-and-mouth disease is globally one of the most economically important viral diseases of cloven-hoofed animals that can be controlled by different strategies, where vaccination plays an important role. Selection of adjuvant added to vaccine preparation is crucial in ensuring the protective effect of the vaccine. Aluminum hydroxide gel mixed with saponin (AS) is widely used adjuvant, with its suboptimal immune response in FMD vaccine. The present study was undertaken to evaluate different ingredients of adjuvants for inactivated trivalent (A, O and SAT 2) FMD vaccine and to demonstrate the effect of booster dose in cattle.

Methods

Cattle were grouped into five; four experimental and one control, with six animals in each group and immunized with trivalent vaccine with various formulations of adjuvants. Immune response was measured using Solid Phase Competitive Enzyme Linked Immune Sorbent Assay (SPCE).

Results

The antibody level in cattle immunised with a vaccine formulation containing a mixture of aluminum hydroxide gel and saponin (AS) were significantly lower than AS boosted group for the three serotypes (p<0.05, t-test), which directs the need for booster dose. Whereas the antibody response in the AS + oil group was higher followed by oil alone. The AS preparation with a booster dose has shown better immune response compared to the group without.

Conclusion

The findings of this study could suggest that oil based and AS with oil could replace the conventional aluminum hydroxide gel and saponin adjuvants in FMD vaccine preparations. Challenge test was not successful indicating the need for further research on the virus infectivity.

Seroprevalence and associated risk factors of peste des petits ruminants among ovine and caprine in selected districts of Afar region, Ethiopia

BACKGROUND

A Peste des petits ruminant is an acute, highly contagious and economically important transboundary viral disease of small ruminants. Despite the fact that food and agriculture organization and world organization for animal health plan to eradicate the disease by 2030, some studies indicated an increasing seropositivity of PPR infection in sheep and goats in Ethiopia. A cross-sectional study was employed to estimate the seroprevalence of PPR and to assess risk factors during the study period, February to April, 2020. Following purposive selection of the study districts, simple random sampling technique was employed to select individual animal during sample collection. A total of 384 serum samples were collected from apparently healthy sheep and goats. Competitive Enzyme Linked Immunosorbent Assay was used to detect the presence of antibodies against PPR at national veterinary institute. Descriptive statistics, Pearson's chi-square (X²) and logistic regression analysis were used is this study.

RESULTS

The overall animal level seroprevalence of PPR virus was found to be 60.15% (n = 231/384) and species level prevalence rate was found to be 38.18% (n = 42) in sheep and 68.98% (n = 189) in goats in the study areas. Among the associated risk factors considered; species, sex, age and herd sizes were significantly associated (P < 0.05) with the disease occurrence. Among the associated risk factors considered in this study, species, sex, age and herd size were found to be statistically associated with the seropositivity of PPR infection.

CONCLUSION

The present study finding revealed that a higher seroprevalence of PPR virus infection and this confirms peste des petits ruminant virus is circulating in Afar region. Further studies should be carried out on the entire region to determine PPR seroprevalence and to develop appropriate control and eradication strategies of PPR disease.

Seroprevalence and associated risk factors of pox infection among sheep and goats in selected districts of Afar region, Ethiopia

Background

Sheep and goat pox virus infection is highly devastating viral disease of small ruminants that cause severe production losses in sheep and goats in Ethiopia and also limits international trade. A cross-sectional study was employed with the objective to estimate the seroprevalence of pox infection and to assess associated risk factors during the study period, February to April, 2020. A total of 384 serum samples were collected from apparently healthy sheep and goats. Serum neutralization test was used to detect the presence of antibodies against pox virus at national veterinary institute. Descriptive statistics, univariable and Multivariable logistic analyses were used in this study.

Results

The overall animal level seroprevalence of sheep and goat pox virus was found to be 15.36% (n = 59/384) and species level prevalence rate was found to be 14.5% (n = 16/110) in sheep and 15.69% (n = 43/274) in goats in the study areas. Among the associated factors considered in this study, sex (P = 0.010), age (P = 0.012) and herd size (P = 0.029) were found to be statistically associated with seropositivity of pox infection in multivariable logistic regression. The odds of seropositivity in female animals were 3.9 times more likely to develop pox infection than male animals (AOR = 2.2; 95% CI = 1.203-4.015%) and the odds of young animals were 2.14 times more likely to be seropositive to pox infection than old aged animals (AOR = 2.14; 95% CI = 1.169-3.633%). Moreover, the odds of large-sized flocks of animals were 3.10 times more likely to be seropositive to pox disease than small-sized flocks (AOR = 3.10; 95% CI = 1.30-4.42%).

Conclusion

This study finding revealed that sheep and goat pox virus is prevalent and widespread diseases of small ruminant in afar region. Therefore, further study should be carried out to estimate region wise magnitude of the disease and control measures should be put in place to minimize the economic losses associated with this disease.

FTA Cards as a Rapid Tool for Collection and Transport of Infective Samples: Experience with Foot-and-Mouth Disease Virus in Libya

Foot-and-mouth disease (FMD) is a viral disease, widespread and highly contagious, that mainly affects cloven-hoofed domestic and wild animals. FMD can lead to high economic losses due to the reduction in animal production such as a drop in milk production, loss of body weight, and a high mortality rate in young ruminants. Sixteen samples were collected from animals showing typical clinical signs of FMD during the last FMD outbreak in Libya in 2018-2019. Flinders Technology Associates (FTA) cards impressed with blood, swabs, or vesicular epithelium samples were shipped to the WOAH FMD reference laboratory in Brescia, Italy, and tested for the detection of FMD viruses. Nucleic acids were extracted from the FTA cards, and molecular testing based on real-time RT-PCR assays was carried out, of which one was specifically designed for the detection of the FMD virus of serotype O, topotype O/East Africa-3 (O/EA-3), that was further confirmed by a sequence analysis of the VP1 gene. The phylogenetic analysis of the VP1 gene showed a nucleotide identity of more than 99% between the virus circulating in Libya and the FMD virus strains isolated in Algeria in 2019.

Investigation of foot and mouth disease virus and other animal pathogens in cattle, buffaloes and goats at the interface with Akagera National Park 2017 - 2020

BACKGROUND

Foot-and-Mouth Disease Virus (FMDV) is a positive-sense RNA virus of the family of the picornaviridæ that is responsible for one of the livestock diseases with the highest economic impact, the Foot-and-Mouth Disease (FMD). FMD is endemic in Rwanda but there are gaps in knowing its seroprevalence and molecular epidemiology. This study reports the FMD seroprevalence and molecular characterization of FMDV in Eastern Rwanda.

RESULTS

The overall seroprevalence of FMD in the study area is at 9.36% in cattle and 2.65% in goats. We detected FMDV using molecular diagnostic tools such as RT-PCR and RT-LAMP and the phylogenetic analysis of the obtained sequences revealed the presence of FMDV serotype SAT 2, lineage II. Sequencing of the oropharyngeal fluid samples collected from African buffaloes revealed the presence of Prevotela ruminicola, Spathidium amphoriforme, Moraxella bovoculi Onchocerca flexuosa, Eudiplodinium moggii, Metadinium medium and Verrucomicrobia bacterium among other pathogens but no FMDV was detected in African buffaloes.

CONCLUSIONS

We recommend further studies to focus on sampling more African buffaloes since the number sampled was statistically insignificant to conclusively exclude the presence or absence of FMDV in Eastern Rwanda buffaloes. The use of RT-PCR alongside RT-LAMP demonstrates that the latter can be adopted in endemic areas such as Rwanda to fill in the gaps in terms of molecular diagnostics. The identification of lineage II of SAT 2 in Rwanda for the first time shows that the categorised FMDV pools as previously established are not static over time.

Temporal and Spatial Patterns and a Space-Time Cluster Analysis of Foot-and-Mouth Disease Outbreaks in Ethiopia from 2010 to 2019

Foot-and-mouth disease (FMD) is an endemic disease in Ethiopia, although space-time cluster and monthly variation studies have never been assessed at national level. The current study aimed to identify the spatial and temporal distribution of FMD outbreaks in Ethiopia from national outbreak reports over a period of ten years from 1 January 2010 to 31 December 2019. To this end, a total of 376,762 cases and 1302 outbreaks from 704 districts were obtained from the Minister of Agriculture for analyses. In general, the dry periods, i.e., October to March, of the year were recorded as the peak outbreak periods, with the highest prevalence in March 2012. The monthly average and the outbreak trends over ten years show a decrease of outbreaks from 2010 to 2019. Decomposing the FMD outbreak data time series showed that once an outbreak erupted, it continued for up to five years. Only 12% of the reported outbreaks were assigned to a specific serotype. Within these outbreaks, the serotypes O, A, SAT-2, and SAT-1 were identified in decreasing order of prevalence, respectively. When a window of 50% for the maximum temporal/space cluster size was set, a total of seven FMD clusters were identified in space and time. The primary cluster with a radius of 380.95 km was identified in the southern part of Ethiopia, with a likelihood ratio of 7.67 (observed/expected cases). The third cluster, with a radius of 144.14 km, was identified in the northeastern part of the country, and had a likelihood ratio of 5.66. Clusters 1 and 3 occurred from January 2017 to December 2019. The second cluster that occurred had a radius of 294.82 km, a likelihood ratio of 6.20, and was located in the central and western parts of Ethiopia. The sixth cluster, with a radius of 36.04 km and a likelihood ratio of 20.60, was set in southern Tigray, bordering Afar. Clusters 2 and 6 occurred in the same period, from January 2014 to December 2016. The fourth cluster in northern Tigray had a calculated radius of 95.50 km and a likelihood ratio of 1.17. The seventh cluster occurred in the north-central Amhara region, with a radius of 97 km and a likelihood ratio of 1.16. Clusters 4 and 7 occurred between January 2010 and December 2013. The spatiotemporal and cluster analysis of the FMD outbreaks identified in the context of the current study are crucial in implementing control, prevention, and a prophylactic vaccination schedule. This study pointed out October to March as well as the main time of the year during which FMD outbreaks occur. The area that extends from the south to north, following the central highlands, is the main FMD outbreak area in Ethiopia.

Diversity of SAT2 foot-and-mouth disease virus in Sudan: implication for diagnosis and control

Like other East African countries, Sudan experienced circulation of more than one topotype of SAT2 foot-and-mouth disease virus (FMDV). In Sudan, topotype XIII of SAT2 virus was recorded in 1977 and 2008 and topotype VII in 2007, 2010, 2013, 2014 and 2017. This work evaluated the impact of such diversity on diagnosis and control. After one or three doses of a vaccine derived from a Sudanese SAT2 virus of topotype VII originated in 2010, heterologous neutralizing antibody titres with Sudanese SAT2 viruses in 2008 were ≤ 1.2 log 10, not consistent with likely protection. Simultaneously, homologous titres were 1.65 (after one dose) or 1.95 and 2.55 log10 (after 3 doses). When r1 values between the vaccine virus and the SAT2 viruses isolated in 2008, whilst topotype XIII was circulating, were derived, values (≈ 0.00) suggested similarly poor antigenic relationship and unlikely cross protection. Concurrently, SAT2 positive field sera from Sudan in 2016 were not unvaryingly identified by virus neutralization tests (VNT) employing SAT2 viruses from 2010 and 2008. Proportions of positive sera by SAT2 virus from 2010 were always higher than those by viruses from 2008; consistent with the more frequent and recent circulation of topotype VII prior to 2016. Proportions by SAT2 virus from 2010 were 0.68 (± 0.1) in one location (n = 72), 0.39 (± 0.1) in another one (n = 94) and 0.52 (± 0.1) in the whole test group (n = 166). Corresponding values by viruses of 2008 were 0.53 (± 0.1), 0.27 (± 0.1) and 0.38 (± 0.1). In the whole test group, differences were statistically significant (p = .02339). Like post-vaccination sera, field sera (natural immunity) showed no considerable cross neutralization between topotype VII and presumably XIII; almost 45% (43/96) of SAT2 positive field sera were positive to one topotype but not to the other. Experimental and surveillance findings emphasized the implication of SAT2 diversity in Sudan. It is concluded that it is difficult to control SAT2 infection in Sudan using a monovalent vaccine. Beside a prophylactic vaccine from topotype VII, stockpiling of antigens from topotype XIII and enhanced virological surveillance with rapid genotyping and matching studies are necessary approaches. When more frequent circulation of more than one SAT2 topotype occurs, retrospective diagnosis by serological surveys could be problematic or imprecise.

Two Cross-Protective Antigen Sites on Foot-and-Mouth Disease Virus Serotype O Structurally Revealed by Broadly Neutralizing Antibodies from Cattle

Foot-and-mouth disease virus (FMDV) is a highly contagious virus that infects cloven-hoofed animals. Neutralizing antibodies play critical roles in antiviral infection. Although five known antigen sites that induce neutralizing antibodies have been defined, studies on cross-protective antigen sites are still scarce. We mapped two cross-protective antigen sites using 13 bovine-derived broadly neutralizing monoclonal antibodies (bnAbs) capable of neutralizing 4 lineages within 3 topotypes of FMDV serotype O. One antigen site was formed by a novel cluster of VP3-focused epitopes recognized by bnAb C4 and C4-like antibodies. The cryo-electron microscopy (cryo-EM) structure of the FMDV-OTi (O/Tibet/99)-C4 complex showed close contact with VP3 and a novel interprotomer antigen epitope around the icosahedral 3-fold axis of the FMDV particle, which is far beyond the known antigen site 4. The key determinants of the neutralizing function of C4 and C4-like antibodies on the capsid were βB (T65), the B-C loop (T68), the E-F loop (E131 and K134), and the H-I loop (G196), revealing a novel antigen site on VP3. The other antigen site comprised two group epitopes on VP2 recognized by 9 bnAbs (B57, B73, B77, B82, F28, F145, F150, E46, and E54), which belong to the known antigen site 2 of FMDV serotype O. Notably, bnAb C4 potently promoted FMDV RNA release in response to damage to viral particles, suggesting that the targeted epitope contains a trigger mechanism for particle disassembly. This study revealed two cross-protective antigen sites that can elicit cross-reactive neutralizing antibodies in cattle and provided new structural information for the design of a broad-spectrum molecular vaccine against FMDV serotype O. IMPORTANCE FMDV is the causative agent of foot-and-mouth disease (FMD), which is one of the most contagious and economically devastating diseases of domestic animals. The antigenic structure of FMDV serotype O is rather complicated, especially for those sites that can elicit a cross-protective neutralizing antibody response. Monoclonal neutralization antibodies provide both crucial defense components against FMDV infection and valuable tools for fine analysis of the antigenic structure. In this study, we found a cluster of novel VP3-focused epitopes using 13 bnAbs against FMDV serotype O from natural host cattle, which revealed two cross-protective antigen sites on VP2 and VP3. Antibody C4 targeting this novel epitope potently promoted viral particle disassembly and RNA release before infection, which may indicate a vulnerable region of FMDV. This study reveals new structural information about cross-protective antigen sites of FMDV serotype O, providing valuable and strong support for future research on broad-spectrum vaccines against FMD.

Seroprevalence and Molecular Detection of Foot and Mouth Disease Virus in Dairy Cattle Around Addis Ababa, Central Ethiopia

BACKGROUND

Foot and mouth disease is a debilitating and highly contagious transboundary disease of cattle that can cause a huge economical loss globally. It is a notifiable disease in Ethiopia, and it is thought to be causing a decrease in cattle productivity and production.

METHODS

A cross-sectional study and outbreak investigation were performed to estimate seroprevalence, identify associated factors and serotypes of FMDV in dairy cattle around Addis Ababa. A multi-stage random sampling technique was employed for the selection of sampling units for the seroprevalence study. A total of 383 blood samples were collected using plain vacutainer tubes and the obtained sera were tested by 3ABC-Ab ELISA at the NAHDIC lab. Also, from outbreak cases, 20 epithelial tissue samples were collected purposively for the molecular detection of FMDV serotypes.

RESULTS

The overall seroprevalence of FMD in dairy cattle was 72.1% (95% CI=67.27-76.50). The seroprevalence in dairy cattle of Ada Berga, Holeta, and Sululta districts was 97.2%, 71.4%, and 57.6%, respectively. Up on Chi-square analysis, age, body condition, and management system were significantly associated with FMD seroprevalence (p<0.05). Besides, multivariable logistic regression analysis showed that district, age, body condition, and management were significantly associated with FMD seroprevalence (p<0.05). The odds of being seropositive to FMD were 6.9 (95% CI=1.8-24.9; p=0.005) and 2.3 (95% CI=1.2-4.7; p=0.01) times higher in cattle found in Ada Berga and Holeta Woreda. From outbreak cases, 18 (90.0%) were identified positive for FMDV serotype O.

CONCLUSION

The current study revealed higher seroprevalence was recorded in the study area and associated risk factors identified statically, serotype O of FMDV was identified from outbreak cases. Therefore, it is critical to design and implement feasible control and prevention mechanisms based on the type of circulating virus serotype.

Vaccine matching and antigenic variability of foot-and-mouth disease virus serotypes O and A from 2018 Ethiopian isolates

Foot-and-mouth disease (FMD) is highly infectious, limits live animal trade, and affects ranchers owing to the loss of animal yield. The present study was designed to perform vaccine matching for field FMD virus isolates from clinically diseased cattle and assess the antigenic properties of the field isolates against the current vaccine strains used for vaccine production at the National Veterinary Institute, Ethiopia. Both sequencing and reverse transcription-polymerase chain reactions were used for distinguishing between the viral strains. To evaluate the serological relationship of the vaccine strain with these field isolates (r1 value), in vitro cross-neutralization was performed using ETH/6/2000 and ETH/38/2005 antisera. Infectious field FMD viral samples represented serotypes A and O. Sequence analysis showed that serotype A VP1/1D possessed amino acid variability at positions 28 and 42 to 48, 138, 141, 142, 148, 156, 173, and 197 compared with the ETH/6/2000 vaccine strain, whereas serotype O possessed amino acid variability at positions 45, 48, 138, 139, 140, 141, and 197 compared with the ETH/38/2005 vaccine strain. Based on the one-dimensional virus neutralization test, serotypes A and O demonstrated antigenic matching of up to 13/17 (76.47%) with the vaccine strain, except for the isolates ETH/40/2018, ETH/48/2018, ETH/55/2018, and ETH/61/2018, which had r-values less than 0.3. Therefore, the currently used vaccine strains ETH/38/2005 for serotype O and ETH/6/2000 for serotype A protected against all and most field viruses characterized as serotypes O and A, respectively, and amino acid residue variation was observed in different FMD virus B-C loops, G-H loops, and C-termini of VP1 at sites 1 and 3 in both serotypes.

Phylogeographic analysis of foot-and-mouth disease virus serotype O dispersal and associated drivers in East Africa

The continued endemicity of foot and mouth disease virus (FMDV) in East Africa has significant implications for livestock production and poverty reduction, yet its complex epidemiology in endemic settings remains poorly understood. Identifying FMDV dispersal routes and drivers of transmission is key to improved control strategies. Environmental heterogeneity and anthropogenic drivers (e.g., demand for animal products) can impact viral spread by influencing host movements. Here, we utilized FMDV serotype O VP1 genetic sequences and corresponding spatiotemporal data in order to (i) infer the recent dispersal history, and (II) investigate the impact of external factors (cattle density, human population density, proximity to livestock markets, and drought) on dispersal velocity, location, and direction of FMDV serotype O in East Africa. We identified statistical evidence of long-distance transmission events, and we found that FMDV serotype O tends to remain circulating in areas of high cattle density, high human population density, and in close proximity to livestock markets. The latter two findings highlight the influence of anthropogenic factors on FMDV serotype O spread in this region. These findings contribute to the understanding of FMDV epidemiology in East Africa and can help guide improved control measures.

Structures of Foot-and-mouth Disease Virus with neutralizing antibodies derived from recovered natural host reveal a mechanism for cross-serotype neutralization

The development of a universal vaccine against foot-and-mouth disease virus (FMDV) is hindered by cross-serotype antigenic diversity and by a lack of knowledge regarding neutralization of the virus in natural hosts. In this study, we isolated serotype O-specific neutralizing antibodies (NAbs) (F145 and B77) from recovered natural bovine hosts by using the single B cell antibody isolation technique. We also identified a serotype O/A cross-reacting NAb (R50) and determined virus-NAb complex structures by cryo-electron microscopy at near-atomic resolution. F145 and B77 were shown to engage the capsid of FMDV-O near the icosahedral threefold axis, binding to the BC/HI-loop of VP2. In contrast, R50 engages the capsids of both FMDV-O and FMDV-A between the 2- and 5-fold axes and binds to the BC/EF/GH-loop of VP1 and to the GH-loop of VP3 from two adjacent protomers, revealing a previously unknown antigenic site. The cross-serotype neutralizing epitope recognized by R50 is highly conserved among serotype O/A. These findings help to elucidate FMDV neutralization by natural hosts and provide epitope information for the development of a universal vaccine for cross-serotype protection against FMDV.

FMDV is the causative agent of foot-and-mouth disease, one of the most contagious and economically devastating diseases of cloven-hoofed animals. The antigenic diversities of the currently known epitopes throughout FMDV serotypes and the lack of understanding of FMDV neutralization in natural hosts limit the development of a vaccine that is able to provide cross-serotype protection. In this work, we isolated FMDV serotype O-specific neutralizing antibodies (NAbs) (F145 and B77) and a serotype O/A cross-reacting NAb (R50) from recovered natural bovine hosts and determined virus-NAb complex structures by cryo-electron microscopy at near-atomic resolution. Structures of virus-NAb complex reveal F145 and B77 engage the capsid of FMDV-O near the icosahedral threefold axis. In contrast, R50 engages the capsids of both FMDV-O and FMDV-A between the 2- and 5-fold axes, revealing a previously unknown antigenic site. This is the first time to present structure details of FMDV neutralization by natural hosts. And this work also provides epitope information for the development of a universal vaccine for cross-serotype protection against FMDV.

Prioritizing smallholder animal health needs in East Africa, West Africa, and South Asia using three approaches: Literature review, expert workshops, and practitioner surveys

Managing the health needs of livestock contributes to reducing poverty and improving the livelihoods of smallholder and pastoralist livestock keepers globally. Animal health practitioners, producers, policymakers, and researchers all must prioritize how to mobilize limited resources. This study employed three approaches to prioritize animal health needs in East and West Africa and South Asia to identify diseases and syndromes that impact livestock keepers. The approaches were a) systematic literature review, b) a series of expert workshops, and c) a practitioner survey of veterinarians and para-veterinary professionals. The top constraints that emerged from all three approaches include endo/ ectoparasites, foot and mouth disease, brucellosis, peste des petits ruminants, Newcastle disease, and avian influenza. Expert workshops additionally identified contagious caprine pleuropneumonia, contagious bovine pleuropneumonia, mastitis, and reproductive disorders as constraints not emphasized in the literature review. Practitioner survey results additionally identified nutrition as a constraint for smallholder dairy and pastoralist small ruminant production. Experts attending the workshops agreed most constraints can be managed using existing veterinary technologies and best husbandry practices, which supports a shift away from focusing on individual diseases and new technologies towards addressing systemic challenges that limit access to veterinary services and inputs. Few research studies focused on incidence/ prevalence of disease and impact, suggesting better incorporation of socio-economic impact measures in future research would better represent the interests of livestock keepers.

The history of foot-and-mouth disease virus serotype C: the first known extinct serotype?

Foot-and-mouth disease (FMD) is a highly contagious animal disease caused by an RNA virus subdivided into seven serotypes that are unevenly distributed in Asia, Africa, and South America. Despite the challenges of controlling FMD, since 1996 there have been only two outbreaks attributed to serotype C, in Brazil and in Kenya, in 2004. This article describes the historical distribution and origins of serotype C and its disappearance. The serotype was first described in Europe in the 1920s, where it mainly affected pigs and cattle but as a less common cause of outbreaks than serotypes O and A. No serotype C outbreaks have been reported in Europe since vaccination stopped in 1990. FMD virus is presumed to have been introduced into South America from Europe in the nineteenth century, although whether serotype C evolved there or in Europe is not known. As in Europe, this serotype was less widely distributed and caused fewer outbreaks than serotypes O and A. Since 1994, serotype C had not been reported from South America until four small outbreaks were detected in the Amazon region in 2004. Elsewhere, serotype C was introduced to Asia, in the 1950s to the 1970s, persisting and evolving for several decades in the Indian subcontinent and for eighteen years in the Philippines. Serotype C virus also circulated in East Africa between 1957 and 2004. Many serotype C viruses from European and Kenyan outbreaks were closely related to vaccine strains, including the most recently recovered Kenyan isolate from 2004. International surveillance has not confirmed any serotype C cases, worldwide, for over 15 years, despite more than 2,000 clinical submissions per year to reference laboratories. Serology provides limited evidence for absence of this serotype, as unequivocal interpretation is hampered by incomplete intra-serotype specificity of immunoassays and the continued use of this serotype in vaccines. It is recommended to continue strengthening surveillance in regions of FMD endemicity, to stop vaccination against serotype C and to reduce working with the virus in laboratories, since inadvertent escape of virus during such activities is now the biggest risk for its reappearance in the field.

Genetic characterization of foot-and-mouth disease virus serotype O isolates collected during 2014-2018 revealed dominance of O/ME-SA/Ind2001e and the emergence of a novel lineage in India

Foot-and-mouth disease (FMD) is endemic in India with a preponderance of outbreaks caused by FMD virus (FMDV) serotype O. Out of the 11 global topotypes of serotype O, only ME-SA topotype has been reported in the country so far. Lineage O/ME-SA/Ind2001 and O/ME-SA/PanAsia are documented as the most dominant ones in terms of the number of outbreaks caused by them. To understand the distribution of topotype/lineages in India and their antigenic behaviour during the year 2014-2018, a total of 286 FMDV serotype O viral isolates were sequence determined at the VP1 region, and 109 isolates were characterized antigenically. All the isolates grouped in the ME-SA topotype, being distributed in lineage O/ME-SA/Ind2001 (within sub-lineages O/ME-SA/Ind2001d and O/ME-SA/Ind2001e), and a new group designated here as O/ME-SA/2018 cluster. The sub-lineage O/ME-SA/Ind2001e reported for the first time in India during the year 2015, replaced sub-lineage O/ME-SA/Ind2001d gradually, which was dominating since 2008. During the years 2014-2018, the sub-lineage O/ME-SA/Ind2001e was found to be the most predominant one whose mean evolutionary rate was observed to be faster than that of the sub-lineage O/ME-SA/Ind2001d. The codon sites 45 and 85 of VP1 were found to be under diversifying selection in a large proportion of trees. The common ancestor predicted for sub-lineages O/ME-SA/Ind2001e and O/ME-SA/2018 dates back to 2012 and 2016, respectively. The sustenance and spread of the new O/ME-SA/2018 cluster need to be assessed by continued surveillance. The Indian vaccine strain O/INDR2/1975 was found to provide adequate antigenic coverage to the emerging and prevalent serotype O lineages. The trait association tests showed frequent virus exchange among different states, which could be an important confounder in the region-specific assessment of effectiveness of FMD control programme.

Isolation, Serotyping, and Molecular Detection of Bovine FMD Virus from Outbreak Cases in Aba'ala District of Afar Region, Ethiopia

Background

On the basis of FMDV outbreak cases, a cross-sectional study was undertaken to collect samples from January 2019 to March 2020 intended for isolation, serotyping, and molecular detection of FMDV in the study district. The purposive sampling method was applied to select the study area for the reason of the presence of FMD outbreak case report during the study period. Totally, 27 FMD clinical samples were collected from affected study population during field outbreak. Out of 27 samples, 18 of them were inoculated on cultured Baby hamster kidney (BHK-21) monolayer cells, and all 27 samples were tested using conventional RT-PCR and sets of specific universal primers. Finally, the PCR products were visualized with UV illumination and imaged with gel documentation system.

Results

The current study results revealed that out of 18 clinical samples subjected to virus isolation, 72.2% (n = 13) of these cultures exhibited FMDV-induced cytopathic effect (CPE) and the identified serotype was SAT-2 FMD virus. Out of 27 clinical samples tested by conventional RT-PCR, only 12 FMDV samples were found to be FMDV positive by universal primers. Out of 27 samples detected by conventional RT-PCR, only 12 FMDV samples were found to be FMDV positive by universal primers.

Conclusions

Our study finding indicated that FMDV is prevalent in the study area and FMDV serotype SAT-2 was the causality for the outbreaks of the disease in the study area. Hence, region-wise FMD outbreak investigation, further phylogenetic analysis, and vaccine matching field isolates should be carried out for effective vaccine development to control the disease.

Molecular characterization of foot-and-mouth disease viruses circulating in Ethiopia between 2008 and 2019

One of the constraints to controlling foot-and-mouth disease (FMD) in East Africa is the incomplete knowledge of the specific FMD virus (FMDV) strains circulating and the way in which these viruses move across countries in the region. This retrospective study focuses on Ethiopia, which has one of the largest FMD-susceptible livestock populations in Africa. Analyses of FMDV positive samples collected between 2008 and 2019 demonstrate that serotypes O (n = 175), A (n = 51) and SAT 2 (n = 33) were present in the country. Phylogenetic analysis of the VP1 sequences for these viruses showed that there were at least seven different FMD viral clades circulating during this period: O/EA-3, O/EA-4, A/AFRICA/G-I, A/AFRICA/G-IV, A/AFRICA/G-VII, SAT2/VII and SAT2/XIII. Although these results only represent a snapshot and might not reflect all FMDV lineages that were present, they highlight the importance of serotype O, as well as the complexity and co-existence of FMDV serotypes in Ethiopia and surrounding countries. These sequence data also support the idea that there are two FMDV ecosystems existing in East Africa. Data from retrospective studies, such as these presented here, will be beneficial for vaccine selection and vaccination campaigns to control FMDV within Ethiopia.

Complex Circulation of Foot-and-Mouth Disease Virus in Cattle in Nigeria

Nigeria is a large densely populated country in West Africa. Most of its livestock is raised in a pastoralist production system with typical long distance migration in search of water and feed. As the demand for animal products largely exceeds the domestic production, large numbers of livestock are imported from neighboring countries without sanitary restrictions. In Nigeria, foot-and-mouth disease virus (FMDV) serotypes O, A, and Southern African Territories (SAT)2 are endemic for a long time. Clinical outbreaks of FMD due to serotype SAT1 are described again since 2015, after an absence of more than 30 years. Historically, outbreaks of FMD due to serotypes O, A, SAT1, and SAT2 were each time associated with trade of cattle entering Nigeria from neighboring countries. In the present study, tissue samples from 27 outbreaks of FMD were collected in Nigerian cattle from 2012 until 2017 in six different States and in the Federal Capital Territory. FMDV was isolated and serotyped and further characterized by VP1 sequencing and phylogenetic analysis to gain more knowledge on FMDV circulation in Nigeria. Half of the outbreaks were characterized as FMDV topotype O/EA-3, while outbreaks with other serotypes and topotypes were—in descending order—less prevalent: A/Africa/G-IV, SAT1/X, SAT2/VII, and O/WA. The high dynamics and omnipresence of FMD in Nigeria were illustrated in Plateau State where FMDV serotypes O, SAT1, and SAT2 were isolated during the course of the study, while at some point in the study, outbreaks due to FMDV serotype A were observed in three remote States. The genetic and phylogenetic analysis suggests a mixed origin of FMD outbreaks. Some outbreaks seem to be caused by sustained local transmission of FMDV strains present in Nigeria since a number of years, while other outbreaks seem to be related to recent incursions with new FMDV strains. The role of African buffaloes in the etiology of FMD in Nigeria is unclear, and sampling of wildlife is needed. The results of the present study suggest that systematic sample collection is essential to understand the complex concomitance of FMDV strains in Nigeria and essential to support the implementation of a vaccination-based control plan.

A vaccine-matching assessment of different genetic variants of serotype O foot-and-mouth disease virus isolated in Ethiopia between 2011 and 2014

The aim of this study was to assess the vaccine-matching and antigenic properties of foot-and-mouth disease virus (FMDV) isolates collected from Ethiopia between 2011 and 2014. Samples (n = 51) were collected from cattle and pigs with clinical signs consistent with foot-and-mouth disease (FMD) on farms in Debre-Berhan, Debre-Zeit/Bishoftu, Sidamo, Mekelle, and Addis Ababa. Infectious FMDV was isolated using BHK-21 cell cultures from 38 of the 51 field samples (74.5%). All of these FMDV-positive samples were characterized as serotype O, belonging to two East Africa topotypes (EA-3 and EA-4), and their VP1-encoding sequences demonstrated amino acid sequence variability encompassing 27 positions in comparison to the vaccine strain (O/ETH/38/2005) currently provided by the National Veterinary Institute of Ethiopia. One-dimensional virus neutralization test (1 dm VNT) results showed that O/ETH/38/2005 was antigenically matched to 10 of the 16 serotype O viruses. These findings indicate that the O/ETH/38/2005 vaccine strain can provide protection against outbreaks caused by the O/EA-3 topotype, although poorer vaccine-matching results for the O/EA-4 topotype reinforce the importance of using a good-quality vaccine with high coverage in the susceptible herds with supporting post-vaccination serosurveillance to ensure that sufficient antibody titers are generated in the vaccinated animals.

Comparative nucleotide sequencing of the VP1 capsid gene of recent isolates of foot-and-mouth disease virus serotype O from Egypt

Since 2006, Egypt has been affected by eleven various foot-and-mouth disease virus (FMDV) lineages. Accordingly, the nucleotide sequences of the 1D gene and the genes encoding the external capsid protein of some isolates of serotype O (the most predominant epidemic serotype in the country) collected from 2004 to 2017 were determined. All of these viruses (including the vaccine strain) belonged to serotype O, topotype ME-SA, and lineage Sharquia-72, and their sequences were of 98.6-98.9% identical to that of strain O1/Sharquia/EGY/72 (DQ164871), and differed from cultured and clinical (D197E) virus strains. The characteristic sites on the surface of the structural proteins of the Egyptian serotype O, topotype ME-SA viruses were located at residues 138 and 198 of VP1, residue 132 of VP2, and residues 56 and 104 of VP3. Furthermore, a phylogenetic tree revealed that Sharquia-72 was the only lineage present in Egypt for many decades prior to 2007. Unfortunately, however, during the last decade, five lineages of two separate topotypes of FMDV serotype O were detected in Egypt. Lineages Sharquia-72 and PanAsia-2 belong to topotype ME-SA and show ~ 14.5 to 17.5% intra-lineage divergence. In addition, lineages Qal-13, Ism-16, and Alx-17 cluster within topotype EA-3 and show ~ 4.5 to 15% intra-lineage diversity. The predecessors of the Egyptian EA-3 viruses are likely to have been from Sudan. Finally, at least a penta- or hexavalent vaccine comprising strains representing the endemic FMDV topotypes should be implemented on a wide scale in Egypt, which could combat the incursion of new lineages.

Molecular characterization of foot-and-mouth disease viruses collected from Northern and Central Ethiopia during the 2018 outbreak

Background and Aim

Foot-and-mouth disease (FMD) is endemic in several developing countries and affects poor farmers through loss of production, death of diseased animals, and loss of animal byproducts. Forty-three samples were collected from 12 sites of five geographical located areas from suspected FMD virus (FMDV)-infected cattle during 2018. This study aimed to isolate and characterize the FMDVs using reverse transcription-polymerase chain reaction (RT-PCR) and gene sequencing.

Materials and Methods

Forty-three FMDV-suspected clinical samples cultured on BHK-21 cell were examined, followed by virus serotype identification using RT-PCR and gene sequencing.

Results

Twenty-nine (67.44%) samples were cultured on BHK-21 cell, of which 14 (32.56%) were not isolated; the 43 samples were analyzed using FMDV screening primers and serotype-specific primers. The contribution of the disease-causing serotype was serotype O of 8 (18.60%) samples, serotype A of 20 (46.51%) samples, and mixed infection (O and A) of 1 (2.33%) sample. Serotypes O and A were further characterized by phylogenetic analysis, which grouped them under East Africa 3 and Africa topotypes of genotype IV, respectively. Interestingly, serotype A was isolated for the 1^st time from Keyet sub-woreda and Mulo woreda of Ethiopia, and mixed serotypes (O and A) were identified from the purchased animal.

Conclusion

Molecular test result, sequencing, and phylogenetic tree reconstruction analysis revealed that the 2018 FMD outbreak in Ethiopia was caused by FMDV serotypes O and A. FMDV serotype A was the predominant strain circulating in most study areas of the country. Infections in one sample with mixed serotypes of O and A were also reported. The authors recommend a vaccine matching study of those field isolated viruses with the vaccine strain.

Seroprevalence and molecular characterization of foot-and-mouth disease virus in Chad

This study aimed at determining the seroprevalence of foot-and-mouth disease (FMD) in domestic ruminants and at characterizing the virus strains circulating in four areas of Chad (East Batha, West Batha, Wadi Fira and West Ennedi). The study was carried out between October and November 2016. A total of 1,520 sera samples (928 cattle, 216 goats, 254 sheep and 122 dromedaries) were collected randomly for FMD serological analyses. Nine epithelial tissue samples were also collected from cattle showing clinical signs, for FMDV isolation and characterization. Serological results showed an overall NSP seroprevalence of 40% (375/928) in cattle in our sample (95% CrI [19-63]). However, seroprevalences of 84% (27/32), 78% (35/45) and 84% (21/25) were estimated in cattle over 5 years of age in East Batha, West Batha and Wadi Fira, respectively. In cattle under 1 year of age, 67% (18/27) seroprevalence was estimated in Wadi Fira, 64% (14/22) in East Batha and 59% (13/22) in West Batha. It was found that the high seroprevalences have been obtained in areas where pastures are shared by several different herds but also in farms where two to three species (bovine, caprine and ovine) are raised together. ELISA PrioCHECK® FMDV types O and A and in-house solid phase competition ELISA serotyping results showed that the four O, A, SAT1 and SAT2 serotypes have circulated in Chad in 2016. However, the type SAT2 dominated with an overall seroprevalence of 43% (29/67) and was present in the four areas investigated. The phylogenetic analyses of the VP1 coding sequence allowed determining the serotype SAT2 topotype VII, close to viral strains found in Cameroon in 2015 with a similarity of 98.60%.

Characterization of transboundary foot-and-mouth disease viruses in Nigeria and Cameroon during 2016

Continuous surveillance for foot-and-mouth disease (FMD) in endemic settings such as West Africa is imperative to support improved local and regional control plans, with the long-term goal of regional eradication. This paper describes the genetic characterization of FMD viruses (FMDV) obtained from outbreaks in Nigeria (n = 45) and Cameroon (n = 15) during 2016 and from archival samples (n = 3) retrieved from a 2014 outbreak in Nigeria. These viruses were analysed in the context of previously published FMDV sequences from the region. Four FMDV serotypes: O, A, SAT1 and SAT2, were detected. Phylogenetic analyses of the VP1 coding sequences indicate the continuity of FMDV serotype O East Africa-3 (O/EA-3), serotype A AFRICA genotype G-IV (A/AFRICA/G-IV) and serotype South African Territories (SAT) 2 lineage VII (SAT2/VII). The FMDV SAT1 topotype X (SAT1/X), which emerged in Nigeria in 2015, continued to be associated with outbreaks in the region during 2016, and SAT1 is reported for the first time from Cameroon. Additionally, a re-emergence or re-introduction of the serotype O West Africa (O/WA) topotype in Nigeria is described herein. Our findings indicate a consistent, pan-serotypic relationship between FMDV strains detected in Cameroon and Nigeria. Additionally, FMDV strains from West Africa obtained in this study were genetically related to those occurring in East and North Africa. These phylogenetic relationships suggest that animal movements (pastoralism and/or trade) are important factors for virus spread across the African continent. These data provide critical baselines which are a necessary component of Stages 0 and 1 of the Progressive Control Pathway of FMD (PCP-FMD). Specifically, characterizing the existing virus strains (risk) provides the basis for the comprehensive risk-based control plan which is the requisite criteria for Nigeria's transition to Stage 2 of PCP-FMD, and for coordinated regional control of FMD.

Cell culture propagation of foot-and-mouth disease virus: adaptive amino acid substitutions in structural proteins and their functional implications

Foot-and-mouth disease is endemic in livestock in large parts of Africa and Asia, where it is an important driver of food insecurity and a major obstacle to agricultural development and the international trade in animal products. Virtually all commercially available vaccines are inactivated whole-virus vaccines produced in cell culture, but the adaptation of a field isolate of the virus to growth in culture is laborious and time-consuming. This is of particular concern for the development of vaccines to newly emerging virus lineages, where long lead times from virus isolate to vaccine can delay the implementation of effective control programs. High antigen yields in production cells are also necessary to make vaccines affordable for less developed countries in endemic areas. Therefore, a rational approach to cell culture adaptation that combines prior knowledge of common adaptive mutations and reverse genetics techniques is urgently required. This review provides an overview of amino acid exchanges in the viral capsid proteins in the context of adaptation to cell culture.

Review on Outbreak Dynamics, the Endemic Serotypes, and Diversified Topotypic Profiles of Foot and Mouth Disease Virus Isolates in Ethiopia from 2008 to 2018

Foot and mouth disease (FMD) endemicity in Ethiopia's livestock remains an ongoing cause for economic concern, with new topotypes still arising even in previously unaffected areas. FMD outbreaks occur every year almost throughout the country. Understanding the outbreak dynamics, endemic serotypes, and lineage profiles of FMD in this country is very critical in designing control and prevention programs. For this, detailed information on outbreak dynamics in Ethiopia needs to be understood clearly. In this article, therefore, we review the spatial and temporal patterns and dynamics of FMD outbreaks from 2008 to 2018. The circulating serotypes and the topotypic profiles of the virus are also discussed. FMD outbreak data were obtained from; reports of MoARD (Ministry of Agriculture and Rural Development)/MoLF (Ministry of livestock and Fishery, NVI (National Veterinary Institute), and NAHDIC (National Animal Health Diagnostic and Investigation Center); published articles; MSc works; PhD theses; and documents from international organizations. To effectively control and prevent FMD outbreaks, animal health agencies should focus on building surveillance systems that can quickly identify and control ongoing outbreaks and implement efficient preventive measures.

Foot and mouth disease outbreak investigation and estimation of its economic impact in selected districts in northwest Ethiopia

Foot and mouth disease (FMD), a highly contagious and economically important disease of cloven-hoofed animals, is endemic in Ethiopia. Foot and mouth disease outbreak investigation and follow-up studies were undertaken to identify the causative serotype, determine the morbidity and mortality, and estimate the economic impact of the outbreaks in selected districts of Northwest Ethiopia. The serotype of FMD virus involved in the outbreaks was identified by antigen detection ELISA from clinical samples. Morbidity, mortality and economic impact of the outbreaks were assessed based on data collected from 738 smallholder farmers in a mixed crop-livestock (MCL) production system and from five dairy farms in the commercial dairy production system. The outbreaks were confirmed to be due to FMD virus serotype O. The animal level morbidity in clinically affected cattle herds was 68.1% for MCL production system and 54.5% for commercial dairy farms. The mortality in cattle in the MCL system was 0.4% and no mortality was recorded in the commercial dairy farms. The animal level morbidity in sheep and goats in the infected flocks was 35.7% but no mortality was seen in these species. The herd/flock level morbidity of FMD in outbreak affected kebeles of MCL system was 57.2% for cattle and 8% for sheep and goats. The economic losses due to milk loss, draught power loss, mortality and treatment cost were on average USD 34 (interquartile range: 9.4-44.4) per affected herd in the MCL system and this was statistically significantly lower than the USD 459.1 (interquartile range: 400.0-486.2) per affected farm in the commercial dairy farms (p < .05). These economic losses have significant impact in the livelihood and income of affected farmers in both production systems. Future work should focus on the implementation of control measures that mitigate the economic impact of the disease.

Characterization of the FMDV-serotype-O isolates collected during 1962 and 1997 discloses new topotypes, CEY-1 and WCSA-1, and six new lineages

The genetic diversity of the FMD viruses collected from the outbreaks during the second half of the 20th Century in Sri Lanka was assessed in the present study. We sequenced the VP1 genomic region of the samples collected during FMDV epidemics caused by serotype O in Sri Lanka during 1962 and 1997. For comparison, we sequenced the VP1 of the related viral isolates collected from other Asian countries. We analyzed the VP1 sequences of the viral strains using the UPGMA method with uncorrected pairwise distances. Nucleotide divergence (ND) thresholds of 15%-20% and 5%-<15% were used to differentiate topotypes and lineages, respectively. We calibrated the divergence times and lineage-specific substitution rates using Bayesian-skyline models. Based on the ND estimations and phylogenetic relationships, we identified and named two new topotypes [CEYLON 1 (CEY-1) and WEST, CENTRAL AND SOUTH ASIA 1 (WCSA-1)] and six new lineages (Syr-62, Srl-77, Tur-69, May-78, Tai-87 and Bur-77) of serotype O. We believe that the novel topotypes and lineages named may have disappeared although they have similar substitution rates for epizootic outbreaks. Because the amino acid selection analysis revealed that the two topotypes and six lineages identified were under purifying selection during the outbreaks.

Serological and molecular epidemiology of foot-and-mouth disease viruses in agro-pastoralist livestock herds in the kachia grazing reserve, Nigeria

The Kachia Grazing Reserve (KGR) is located in Kaduna state in north-western Nigeria and consists of 6 contiguous blocks housing 744 defined households (HH), all engaged in livestock keeping. It is considered as a homogenous epidemiological unit and a defined study area. In 2012, all cattle and sheep of 40 selected HH were sampled to determine sero-prevalence of antibodies to foot-and-mouth disease virus (FMDV) and of FMDV. The overall sero-prevalence of antibodies to the non-structural 3ABC protein (NSP-3ABC ELISA) was 28.9% (380/1,315) (30.6% cattle; 16.3% sheep), and in 4.5% (62/1,380) (5% cattle; 0.6% sheep) of the examined sera FMD viral RNA could be detected by real-time RT-PCR (rRT-PCR). Additionally, in 2012 and 2014 serum, epithelium and probang samples were collected from cattle in reported FMD outbreaks and the causative FMDVs were molecularly characterized. Approximately half (28/59) of the outbreak sera reacted positive in NSP-3ABC ELISA, and 88% (52/59) of the outbreak sera contained detectable viral RNA. Overall, antibodies against five FMDV serotypes (O, A, SAT1, SAT2 and SAT3) were detected by solid phase competitive ELISA with combinations of two or more serotypes being common. Of the 21 FMDVs that could be isolated 19 were sequenced and 18 were confirmed as SAT2 (lineage VII) while one was characterized as serotype O (EA-3 topotype). Phylogenetic analysis revealed a close relationship between Nigerian FMDV strains and strains in this region and even with strains in North-Africa. Our findings indicate that FMD constitutes an endemic health problem to cattle rearing in the agro-pastoralist community in the KGR and that the KGR is not a closed epidemiological unit. Insight into the local FMDV epidemiology and in the circulating FMDV serotypes/strains is of support to the relevant authorities in Nigeria when considering the need for an FMD control policy to improve animal production in grazing reserves.

Identification of novel epitopes in serotype O foot-and-mouth disease virus by in vitro immune selection

Foot-and-mouth disease virus (FMDV) displays various epitopes on the capsid outer surface. In addition to the five neutralizing antigenic sites, there is evidence of the existence of other, yet unidentified, epitopes that are believed to play a role in antibody-mediated protection. Previous attempts to identify these epitopes revealed two additional substitutions at positions VP2-74 and -191 (5M2/5 virus) to be of antigenic significance. However, complete resistance to neutralization was not obtained in the neutralization assay, indicating the existence of other, undisclosed epitopes. Results from this study provides evidence of at least two new neutralizing epitopes involving residues VP3-116 and -195 around the threefold axis that have significant impact on the antigenic nature of the virus. These findings extend our knowledge of the surface features of the FMDV capsid known to elicit neutralizing antibodies, and should help with rational vaccine design.

Sero-Epidemiology of Foot and Mouth Disease in Domestic Ruminants in Amhara Region, Ethiopia

This study involved cross-sectional serological and questionnaire-based surveys to investigate the sero-epidemiology of foot and mouth disease (FMD) in domestic ruminants, and farmers' knowledge and practices about the disease in the Amhara region of Ethiopia. A multistage cluster sampling was carried out to select domestic ruminants for serological sampling and for the interview with farmers. A total of 1,672 sera samples were collected and tested using a 3ABC-Enzyme Linked Immunosorbent Assay, and 170 farmers were interviewed. An overall FMD apparent seroprevalence of 11.48% (95% CI: 7.52-17.14%) was recorded in the domestic ruminants. The overall true prevalence was 12.04%. The seroprevalence of FMD was higher in cattle (14.37%) than in goats (7.10%) and sheep (7.07%). The age stratified seroprevalence in the districts showed that 66.67% of the districts studied experienced a FMD outbreak within the preceding year of the study time. A mixed effect logistic regression analysis revealed that agroecology, the production system and the age of the animal was significantly associated with FMD seropositivity in cattle (P < 0.05). A statistically significant (P < 0.05) positive correlation (r = 0.93) was observed between cattle and small ruminant FMD seroprevalences. About 82% of the farmers interviewed knew of FMD and 85% of them had experienced the disease in their own herds before. The farmers mostly employ traditional means to control FMD. In conclusion, the findings of the study indicated that FMD is a prevalent disease in the Amhara region with more importance in the intensive production systems and the lowlands of the region. High correlation in seroprevalence between small and large ruminants indicated a possible cross transmission between these species. Therefore, small ruminants should not be overlooked in FMD control. Farmers in the region have a good level of knowledge about the disease; however, currently they heavily rely on traditional practices primarily focused on treating wounds of infected animals. This calls for extension work on available effective preventive measures of the disease, such as vaccination and movement restriction.

The Pseudoknot Region of the 5' Untranslated Region Is a Determinant of Viral Tropism and Virulence of Foot-and-Mouth Disease Virus

This study demonstrates that the deletion in the PK region occurred naturally in the FMDV genome. The isolated O/ME-SA/PanAsia lineage FMDV with an 86-nt deletion in the PK region showed a pig-adapted characteristic that could cause clinical signs in swine but not bovines. Compared to the wild-type FMDV strain, which possesses full infection capacity in both swine and bovines, the recombinant virus with the 86-nt deletion in the PK region is deficient in causing disease in bovines. Deletion of the previously reported 43 nt in the PK region also led to significantly decreased pathogenicity of FMDV in bovines. This study indicates that the PK region is a novel determinant of the tropism and virulence of FMDV.

Foot-and-mouth disease virus (FMDV) is the causative agent of foot-and-mouth disease. It is characterized by genetic instability and different antigenic properties. The nonstructural protein 3A is a primary determinant of the tropism and virulence of Cathay topotype FMDVs. However, several other determinants are also speculated to be involved in viral tropism and virulence. Deletion of 43 nucleotides (nt) in the pseudoknot (PK) region of the 5′ untranslated region (UTR) has been found to coexist with the identified 3A deletion in Cathay topotype FMDV genomes. In this study, we isolated an O/ME-SA/PanAsia lineage FMDV strain, O/GD/CHA/2015, that includes an 86-nt deletion in the PK region and shows a porcinophilic phenotype. To investigate the potential role of the PK region in viral pathogenicity, we generated a recombinant FMDV strain with an incomplete PK region and compared its virulence and pathogenesis to the intact FMDV strain in swine and bovines. Deletion of the 86 nt in the PKs had no major effects on the pathogenicity of the virus in swine but significantly attenuated its ability to infect bovine cells and cattle, indicating that the PK region is a newly discovered determinant of viral tropism and virulence. The role of the 43-nt deletion existing in the Cathay topotype FMDV was also investigated by evaluating the infection properties of genetically engineered viruses. Consistently, the 43-nt deletion in the PK region significantly decreased the pathogenicity of the virus in bovines. Overall, our findings suggest that the PK region deletion occurred naturally in the FMDV genome and that the PK region is highly associated with viral host range and functions as a novel determinant for FMDV pathogenesis.

IMPORTANCE This study demonstrates that the deletion in the PK region occurred naturally in the FMDV genome. The isolated O/ME-SA/PanAsia lineage FMDV with an 86-nt deletion in the PK region showed a pig-adapted characteristic that could cause clinical signs in swine but not bovines. Compared to the wild-type FMDV strain, which possesses full infection capacity in both swine and bovines, the recombinant virus with the 86-nt deletion in the PK region is deficient in causing disease in bovines. Deletion of the previously reported 43 nt in the PK region also led to significantly decreased pathogenicity of FMDV in bovines. This study indicates that the PK region is a novel determinant of the tropism and virulence of FMDV.

Foot-and-mouth disease in Southern Ghana: occurrence and molecular characterization of circulating viruses

Foot-and-mouth disease (FMD) is considered to be endemic in Ghana. However, our knowledge of the local epidemiology of the disease is restricted by a lack of serological information and data for characterized viruses causing field outbreaks. In order to improve our understanding of the prevailing situation, this study was initiated to establish the FMD viruses (FMDV) circulating in the country. During 2016, sera (n = 93) and epithelia/oral swab (n = 20) samples were collected from cattle from four districts in Southern Ghana that experienced FMD outbreaks. Sera were analyzed using the PrioCHECK® FMDV non-structural protein (NSP) ELISA whereas the epithelia/oral swab samples were examined by virus isolation, antigen ELISA, reverse transcription polymerase chain reaction (RT-PCR), and sequencing of VP1 followed by phylogenetic analysis. Assay for antibodies against FMDV NSPs provided evidence of exposure to FMDV in 88.2% (82/93) of the sera tested. Serotypes O and A viruses were detected from clinical samples by RT-PCR and sequencing of VP1. Phylogenetic analysis of VP1 coding sequences revealed that the serotype O viruses belonged to the West Africa (WA) topotype and were most closely related to viruses from Niger and Benin, while the serotype A viruses clustered within genotype IV (G-IV) of the Africa topotype and were most closely related to viruses from Nigeria. This study provides useful information on FMDV serotypes and viral lineages that circulate in Ghana and West Africa that may aid in the formulation of effective FMD control strategies.

Low topotype diversity of recent foot-and-mouth disease virus serotypes O and A from districts located along the Uganda and Tanzania border

Foot-and-mouth disease (FMD) is one of the most important livestock diseases in East Africa with outbreaks reported annually that cause severe economic losses. It is possible to control disease using vaccination, but antigenic matching of the vaccine to circulating strains is critical. To determine the relationship between foot-and-mouth disease viruses circulating in districts along the Uganda and Tanzanian border between 2016 and 2017 and currently used vaccines, phylogenetic analysis of the full VP1 virus sequences was carried out on samples collected from both sides of the border. A total of 43 clinical samples were collected from animals exhibiting signs of FMD and VP1 sequences generated from 11 of them. Eight out of the 11 sequences obtained belonged to serotype O and three belonged to serotype A. The serotype O sequences obtained showed limited nucleotide divergence (average of 4.9%) and belonged to topotype East Africa-2, whereas the most common O-type vaccine strain used in the region (O/KEN/77/78) belonged to East Africa-1. The serotype A viruses belonged to topotype Africa-G1 (average nucleotide divergence 7.4%), as did vaccine strain K5/1980. However, vaccine strain K35/1980 belonged to Africa G VII with an average sequence divergence of 20.5% from the study sequences. The genetic distances between current vaccine strains and circulating field strains underscores the crucial need for regular vaccine matching and the importance of collaborative efforts for better control of FMD along this border area.

Development of a New RT-PCR with Multiple Primers for Detecting Southern African Territories Foot-and-mouth Disease Viruses

Introduction

The extremely high genetic variation and the continuously emerging variants of foot-and-mouth disease virus (FMDV) of Southern African Territory (SAT) serotypes including SAT1, SAT2, and SAT3 make it necessary to develop a new RT-PCR for general use for monitoring viruses based on the updated genome information.

Material and Methods

A FMDV SAT-D8 one-step RT-PCR was established based on the 1D2A2B genes of the SAT serotype viruses with a multiplex primer set. FMDV A, O, C, and Asia 1 serotypes, other vesicular disease viruses, inactivated SAT viruses, and 125 bovine, ovine, caprine and porcine tissue samples collected from the Chinese mainland were included for evaluating the assay.

Results

The new RT-PCR was proven to be specific without cross-reactions with Eurasian FMDV, swine vesicular disease virus (SVDV), Seneca valley virus (SVV), or other common viral pathogens of cattle, sheep, goat, and pig. An around 257 bp-sized amplicon clearly appeared when the inactivated SAT viruses were detected. However, all 125 samples collected from FMDV-susceptible animals from the Chinese mainland which has not known SAT epidemics showed negative results.

Conclusions

A FMDV SAT-D8 one-step RT-PCR is a promising method for primary screening for FMDV SAT serotypes.

Generation of monoclonal antibodies against foot-and-mouth disease virus SAT 2 and the development of a lateral flow strip test for virus detection

Foot-and-mouth disease (FMD) remains a major economic concern for the livestock productivity in many developing countries and a continued threat to countries that are disease free because of its potential devastating impact on agricultural, food chain and tourism sectors. FMD virus (FMDV) is recognized as having seven serotypes: O, A, C, Asia 1, South African Territories (SAT) 1, 2, 3 and multiple subtypes within each serotype. FMD outbreaks due to SAT 2 have been reported in many African countries. The development of a rapid and easily performed test for FMD detection is critical for controlling FMD outbreaks and containing its spread. The present project developed a lateral flow immunochromatographic (LFI) strip test for the rapid detection of FMDV SAT 2. A panel of monoclonal antibodies (mAbs) against FMDV serotype SAT 2 was produced and characterized. One mAb (#10) was selected as the capture mAb because it reacted to all 23 SAT 2 isolates archived at the National Center for Foreign Animal Disease. The LFI strip test was developed using biotin-conjugated mAb #10, and the colloid gold-conjugated FMDV serotype-independent mAb as the detection mAb. A generic Rapid Assay Device (gRAD) with one test line and a control line was used for the test. The LFI strip test detected all 23 tested SAT 2 isolates and recent outbreak strains. The results indicated that the diagnostic specificity and sensitivity of the LFI strip test were greater than the double antibody sandwich (DAS) DAS ELISA. The ability of the LFI strip test to produce rapid diagnostic results will be useful for early on-site diagnosis during FMD outbreaks.