Yemen and Vietnam capripoxviruses demonstrate a distinct host preference for goats compared with sheep

Cross-Protection of an Inactivated and a Live-Attenuated Lumpy Skin Disease Virus Vaccine against Sheeppox Virus Infections in Sheep

Sheeppox virus (SPPV) (genus Capripoxvirus, family Poxviridae) infections are a highly virulent and contagious disease of sheep with a high morbidity and mortality, especially in naïve populations and young animals. For the control of SPPV, homologous and heterologous live-attenuated vaccines are commercially available. In our study, we compared a commercially available live-attenuated lumpy skin disease virus (LSDV) vaccine strain (Lumpyvax) with our recently developed inactivated LSDV vaccine candidate regarding their protective efficacy against SPPV in sheep. Both vaccines were proven to be safe in sheep, and neither clinical signs nor viremia could be detected after vaccination and challenge infection. However, the local replication of the challenge virus in the nasal mucosa of previously vaccinated animals was observed. Because of the advantages of an inactivated vaccine and its heterologous protection efficacy against SPPV in sheep, our inactivated LSDV vaccine candidate is a promising additional tool for the prevention and control of SPPV outbreaks in the future.

The emergence of novel Iranian variants in sheeppox and goatpox viral envelope proteins with remarkably altered putative binding affinities with the host receptor

The outbreak of Sheep and goat pox (SGP) viral infections have increasingly been reported despite vaccinating the majority of sheep populations in Iran. The objective of this study was to predict the impacts of the SGP P32/envelope variations on the binding with host receptors as a candidate tool to assess this outbreak. The targeted gene was amplified in a total of 101 viral samples, and the PCR products were subjected to Sanger sequencing. The polymorphism and phylogenetic interactions of the identified variants were assessed. Molecular docking was performed between the identified P32 variants and the host receptor and the effects of these variants were evaluated. Eighteen variations were identified in the investigated P32 gene with variable silent and missense effects on the envelope protein. Five groups (G1-G5) of amino acid variations were identified. While there were no amino acid variations in the G1 (wild-type) viral protein, G2, G3, G4, and G5 proteins had seven, nine, twelve, and fourteen SNPs, respectively. Based on the observed amino acid substitutions, multiple distinct phylogenetic places were occupied from the identified viral groups. Dramatic alterations were identified between G2, G4, and G5 variants with their proteoglycan receptor, while the highest binding was revealed between goatpox G5 variant with the same receptor. It was suggested that the higher severity of goatpox viral infection originated from its higher affinity to bind with its cognate receptor. This firm binding may be explained by the observed higher severity of the SGP cases from which G5 samples were isolated.

An Extensive Examination of the Warning Signs, Symptoms, Diagnosis, Available Therapies, and Prognosis for Lumpy Skin Disease

The lumpy skin disease virus (LSDV) infects cattle and buffalo and causes lumpy skin disease (LSD). It affects the lymph nodes of the sick animals, causing them to enlarge and appear as lumps (cutaneous nodules) that are 2–5 cm in diameter on their heads, necks, limbs, udders, genitalia, and perinea. A high temperature, a sharp drop in milk supply, discharge from the eyes and nose, salivation, a loss of appetite, depression, damaged hides, and emaciation are further warning signs and symptoms. As per the Food and Agriculture Organization (FAO), the incubation period, or the time between an infection and symptoms, is approximately 28 days. Infected animals can transfer the virus by direct contact with the vectors, direct virus secretion from mouth or nose, shared feeding and watering troughs, and even artificial insemination. The World Organization for Animal Health (WOAH) and the FAO both warn that the spread of illnesses could lead to serious economic losses. This illness reduces cow’s milk production because oral ulcers make the animal weak and lead them to lose their appetite. There are many diagnostics available for LSDV. However, very few tests yield accurate findings. The best methods for preventing and controlling the lumpy skin condition include vaccination and movement restrictions. As a specific cure is not available, the only available treatment for this illness is supportive care for cattle. Recently, India has developed a homologous, live-attenuated vaccine, Lumpi-ProVacInd, which is specifically intended to protect animals against the LSD virus. This study’s primary goal is to accumulate data on symptoms, the most accurate method of diagnosis, treatments, and controls to stop infections from spreading as well as to explore future possibilities for the management of LSDV.

Spatiotemporal and seasonality analysis of sheep and goat pox (SGP) disease outbreaks in Turkey between 2010 and 2019

Sheep and goat pox (SGP) is a highly infectious disease with a high case fatality rate. It causes serious economic losses and decreases productivity in infected facilities and contact areas. As in many countries of the world, SGP outbreaks reported from Turkey to the World Organization for Animal Health (OIE) continue to threaten animal health. Therefore, studies that will guide the production of effective policies to prevent and control SGP are extremely important. This study aims at evaluating the spatiotemporal distribution of SGP outbreaks by geographical information system (GIS)-based analyses. In accordance with this purpose, spatiotemporal scan analyses were applied to reveal the spatiotemporal distribution pattern and transmission of SGP outbreaks reported in Turkey between 2010 and 2019. Space-time cluster analysis revealed 4 several clusters, indicating geographic areas at the highest risk. Spatiotemporal clusters were 6 to 11 times more likely to be exposed to SGP than the general distribution. The average spatiotemporal density of outbreaks in clusters was estimated as 0.20 ± 0.07 outbreaks per 1000 km² per month. Seasonal analysis and time series analysis showed similar findings. The seasonality of SGP was mainly defined in the winter (from December to February) when the seasonal adjusted factor (SAF) was at a peak of 504.6. In addition, February had the highest SAF with 7.1. Directional distribution analysis showed that the transmission of SGP was oriented between northeast (NE)-southwest (SW) and northwest (NW)-southeast (SE) and that distribution was changed every 2 years. These findings present a basis for the effective monitoring and prevention of SGP and provide valuable information to policymakers.

Genetic characterization of sheep pox virus strains from outbreaks in Central Russia in 2018-2019

This study investigates the phylogenomic relatedness between sheep pox viruses (SPPVs) circulating in Central Russia in 2018-2019 with the NISKHI vaccine strain used in the country, based on their complete genome sequences. The sheep pox outbreaks occurred 1 year apart in the adjacent regions of Tula and Moscow. Full genome sequences were generated by sequencing DNA directly obtained from Trizol-extracted scabs, using the DNBSEQ-400 platform (MGI Tech, China). Phylogenetic analysis indicated that the SPPV isolates from Russia clusters with previously published sequences from Srinagar in the Kashmir province of India in 2000 (SPPV-Srinagar strain) as well as SPPV A strain from Kazakhstan in 2000. The aforementioned cluster belonged to a sister clade containing the NISKHI vaccine strain, thus indicating that the recent outbreaks were not genetically linked to the widely used vaccine.

A field study evaluating the humoral immune response in Mongolian sheep vaccinated against sheeppox virus

Sheeppox is a transboundary disease of small ruminants caused by infection with the capripoxvirus sheeppox virus. Sheeppox is found in Africa, the Middle East and Asia and is characterized by fever, multifocal cutaneous raised lesions and death. Vaccination with live attenuated capripoxvirus (CPPV) strains is an effective and widely used strategy to contol sheeppox outbreaks; however, there are few reports of post-vaccination field surveillance studies. This study used a commercially available enzyme-linked immunosorbent assay (ELISA) to examine quantitative and temporal features of the humoral response of sheep vaccinated with a live-attenuated CPPV strain in Mongolia. Four hundred samples were tested using the ELISA commercial kit, and a subset of 45 samples were also tested with a virus neutralization test (VNT). There was substantial agreement between the VNT and ELISA tests. Antibodies to CPPV were detected between 40 and 262 days post-vaccination. There was no significant difference between serological status (positive/negative) and sex or age; however, an inverse correlation was found between the length of time since vaccination and serological status. Animals between 90 and 180 days post-vaccination were more likely to be positive than animals greater than 180 days post-vaccination. Our results show that a commercial CPPV ELISA kit is a robust and reliable assay for post-CPPV vaccination surveillance in resource-restricted settings and provide temporal parameters to be considered when planning sheeppox post-vaccination monitoring programmes.

Seroprevalence of sheeppox and goatpox virus in Asia and African continent: A systematic review and meta-analysis (Scientometrics)

Background and Aim:

Two endemic capripox infectious diseases, sheeppox (SP) and goatpox (GP) are common in Asia, Africa, and the Middle East. Sheep and goats, in general, are considered current assets of small and marginal farmers and have significant economic value in terms of meat, wool, and skin/hide production. Sheep and goat populations in India total 148.88 million and 74.26 million, respectively. Capripox caused US$ 2.3 million (Indian Rupee [INR] 105 million) in economic damages in Maharashtra (India) alone, and it took over 6 years for a flock to recover from the outbreak. The projected yearly loss at the national level is US$ 27.47 million (INR 1250 million). As a result, Capripox diseases put small and marginal farmers under much financial strain. The present study estimates the seroprevalence of SP and GP diseases in the Asian and African continents using systematic review and meta-analysis. The results of the study will help researchers and policymakers to understand the spatial and temporal distribution of the disease and its burden. In addition, the results are also helpful to design and implement location-specific prevention and eradication measures against these diseases.

Materials and Methods:

Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines of Cochran collaborations were used for systematic review and subsequently meta-analysis were used. The literature was collected from various databases. Initial search string resulted in more than nine thousand articles for the period 2000 to 2020 using the different combinations of keywords and Boolean operators (or not) asterisk* and quotation marks. Out of 9398 papers, 80 studies were chosen for complete test reviews and quality bias evaluation using the inclusion and exclusion criteria. Finally, 21 articles were used for the meta-analysis. The statistical study employed fixed effects and random effects models using R.

Results:

Seroprevalence of SP and GP was calculated using studies with a cumulative sample size of 4352, out of which sheep and goats’ samples together contribute 48%, followed by sheep (32%) and goat (21%). The result of the meta-regression revealed that detection techniques had a significant impact on the overall effect size at 5% level (Qm=14.12). Subgroup analysis of polymerase chain reaction (PCR) test with samples was further grouped into two categories based on the median, and it revealed that 62% of samples used PCR as a detecting test followed by group-II.

Conclusion:

From the study, it is concluded that SP and GP diseases are highly prevalent; hence, effective vaccines, proper education to farmers through extension activity, and transboundary disease movement restriction are necessary for the control and eradication of the disease.

Inhibition of bovine and ovine capripoxviruses (Lumpy skin disease virus and Sheeppox virus) by ivermectin occurs at different stages of propagation in vitro

Capripoxvirus diseases are listed as reportable diseases by World Organization for Animal Health (OIE). Lumpy skin disease virus (LSDV) and sheeppox virus (SPPV), which can only be distinguished by molecular analysis, cause moderately, severe, or sometimes fatal infections in cattle and sheep. Even though vaccines are the most effective way to control the infection, their effectiveness may decrease in some cases. Therefore, it is significant to explore antiviral drugs against these diseases along with the vaccine. This study aimed to investigate the antiviral efficiency of ivermectin (IVM) at different stages of in vitro replication of LSDV and SPPV. For this purpose, viral titers (TCID₅₀/mL) of the viruses not treated with IVM (0.0 μM) and treated with non-cytotoxic concentrations of IVM (1.0 and 2.5 μM) were compared during a nine-day (216 h) post-infection period by viral titration assay. At 2.5 μM concentrations of IVM, the mean viral titer was significantly (P<0.05) reduced by approximately three logs for the replication stage of LSDV and SPPV. To evaluate the antiviral activity of IVM against LSDV and SPPV by treatment at the virus attachment and penetration stages, the titers of the virus either untreated or treated with 2,5 μM IVM were compared by virus titration assay. The number of infectious virions for LSDV and SPPV were decreased by 99.82% and 99.87% at the viral replication stage, 68.38% and 25.01% at the attachment stage, and 57.83% and 0.0% at the penetration stage, respectively. It was determined that ivermectin is statistically more effective on LSDV than SPPV at the virus attachment and penetration stages (P<0.05). This study found that the drug IVM can inhibit capripoxviruses, including LSDV and SPPV at various stages of the propagation. Moreover, this research predicted the in vitro antiviral ability of IVM against capripoxvirus infections for the first time.

Outbreak Investigation and Molecular Detection of Pox Virus Circulating in Sheep and Goats in Selected Districts of West Gojjam and Awi Zones Northwest, Ethiopia

INTRODUCTION

Sheep and goat pox virus (SGPV) is a systemic contagious disease causing extreme illness and death in small ruminants.

METHODS

A cross-sectional study was conducted in West Gojjam and Awi zone of Amhara national regional state Northwest Ethiopia, from November 2018 to May 2019 with the objective of pox virus outbreak investigation and molecular detections in sheep and goats (shoats). The study included clinical examinations of lesions, laboratory analysis, and questionnaire survey. Study locations were selected randomly when an active outbreak was reported and observed.

RESULTS

A total of 485 small ruminants (303 sheep and 182 goats) suspected of shoat pox were examined for the presence of specific skin lesions, 71 (14.64%) showed pox lesions, 35 (11.55%) sheep and 36 (19.78%) goats, and 24 (4.95%) had died. The study revealed highest morbidity rate in Jawie (31.25%) and Gunagua (14.89%) districts in goats and sheep, respectively. Lowest morbidity rate was recorded in Dega Damot district in sheep (6.45%) and goats (7.14%), respectively. The mortality rate was >1% in all districts except Dega Damot for both species. From a total of 38 tissue samples, 19 samples were selected based on the geographical distribution. All 19 samples (6 sheep and 13 goats) were found to be positive for goat pox virus based on polymerase chain reaction results. The significant risk factors were free animal movements, age, flock size and composition, body condition, vaccination status, and season. The study showed that in the absence of free movement of animals, the disease was less likely to occur (OR = 0.05, CI 95%; 0.02, 0.15).

CONCLUSION

The disease was found in higher rate during the dry and short rainy season. Sheep were also found to be infected by goat pox virus. The study indicated that there was widespread sheep and goat pox in Northwest Ethiopia.

Review of sheep and goat pox disease: current updates on epidemiology, diagnosis, prevention and control measures in Ethiopia

Sheep pox, goat pox, and lumpy skin diseases are economically significant and contagious viral diseases of sheep, goats and cattle, respectively, caused by the genus Capripoxvirus (CaPV) of the family Poxviridae. Currently, CaPV infection of small ruminants (sheep and goats) has been distributed widely and are prevalent in Central Africa, the Middle East, Europe and Asia. This disease poses challenges to food production and distribution, affecting rural livelihoods in most African countries, including Ethiopia. Transmission occurs mainly by direct or indirect contact with infected animals. They cause high morbidity (75-100% in endemic areas) and mortality (10-85%). Additionally, the mortality rate can approach 100% in susceptible animals. Diagnosis largely relies on clinical symptoms, confirmed by laboratory testing using real-time PCR, electron microscopy, virus isolation, serology and histology. Control and eradication of sheep pox virus (SPPV), goat pox virus (GTPV), and lumpy skin disease (LSDV) depend on timely recognition of disease eruption, vector control, and movement restriction. To date, attenuated vaccines originating from KSGPV O-180 strains are effective and widely used in Ethiopia to control CaPV throughout the country. This vaccine strain is clinically safe to control CaPV in small ruminants but not in cattle which may be associated with insufficient vaccination coverage and the production of low-quality vaccines.

The Importance of Quality Control of LSDV Live Attenuated Vaccines for Its Safe Application in the Field

Vaccination is an effective approach to prevent, control and eradicate diseases, including lumpy skin disease (LSD). One of the measures to address farmer hesitation to vaccinate is guaranteeing the quality of vaccine batches. The purpose of this study was to demonstrate the importance of a quality procedure via the evaluation of the LSD vaccine, Lumpivax (Kevevapi). The initial PCR screening revealed the presence of wild type LSD virus (LSDV) and goatpox virus (GTPV), in addition to vaccine LSDV. New phylogenetic PCRs were developed to characterize in detail the genomic content and a vaccination/challenge trial was conducted to evaluate the impact on efficacy and diagnostics. The characterization confirmed the presence of LSDV wild-, vaccine- and GTPV-like sequences in the vaccine vial and also in samples taken from the vaccinated animals. The analysis was also suggestive for the presence of GTPV-LSDV (vaccine/wild) recombinants. In addition, the LSDV status of some of the animal samples was greatly influenced by the differentiating real-PCR used and could result in misinterpretation. Although the vaccine was clinically protective, the viral genomic content of the vaccine (being it multiple Capripox viruses and/or recombinants) and the impact on the diagnostics casts serious doubts of its use in the field.

Capripoxvirus Infections in Ruminants: A Review

Lumpy skin disease, sheeppox, and goatpox are notifiable diseases of cattle, sheep, and goats, respectively, caused by viruses of the Capripoxvirus genus. They are responsible for both direct and indirect financial losses. These losses arise through animal mortality, morbidity cost of vaccinations, and constraints to animals and animal products' trade. Control and eradication of capripoxviruses depend on early detection of outbreaks, vector control, strict animal movement, and vaccination which remains the most effective means of control. To date, live attenuated vaccines are widely used; however, conferred protection remains controversial. Many vaccines have been associated with adverse reactions and incomplete protection in sheep, goats, and cattle. Many combination- and recombinant-based vaccines have also been developed. Here, we review capripoxvirus infections and the immunity conferred against capripoxviruses by their respective vaccines for each ruminant species. We also review their related cross protection to heterologous infections.

In vitro and in vivo analyses of co-infections with peste des petits ruminants and capripox vaccine strains

BACKGROUND

Peste des petits ruminants (PPR) and goat pox (GTP) are two devastating animal epidemic diseases that affect small ruminants. Vaccination is one of the most important measures to prevent and control these two severe infectious diseases.

METHODS

In this study, we vaccinated sheep with PPR and POX vaccines to compare the changes in the antibody levels between animals vaccinated with PPRV and POX vaccines alone and those co-infected with both vaccines simultaneously. The cell infection model was used to explore the interference mechanism between the vaccines in vitro. The antibody levels were detected with the commercial ELISA kit. The Real-time Quantitative PCR fluorescent quantitative PCR method was employed to detect the viral load changes and cytokines expression after the infection.

RESULTS

The concurrent immunization of GTP and PPR vaccine enhanced the PPR vaccine's immune effect but inhibited the immune effect of the GTP vaccine. After the infection, GTP and PPR vaccine strains caused cytopathic effect; co-infection with GTP and PPR vaccine strains inhibited the replication of PPR vaccine strains; co-infection with GTP and PPR vaccine strains enhanced the replication of GTP vaccine strains. Moreover, virus mixed infection enhanced the mRNA expressions of TNF-α, IL-1β, IL-6, IL-10, IFN-α, and IFN-β by 2-170 times. GTP vaccine strains infection alone can enhanced the mRNA expression of IL-1β, TNF-α, IL-6, IL-10, while the expression of IFN-α mRNA is inhibited. PPR vaccine strains alone can enhanced the mRNA expression of IFN-α, IFN-β, TNF-α, and has little effect the mRNA expression of IL-1β, IL-6 and IL-10. The results showed that GTP and PPR vaccine used simultaneously in sheep enhanced the PPR vaccine's immune effect but inhibited the immune effect of the GTP vaccine in vivo. Furthermore, an infection of GTP and PPR vaccine strains caused significant cell lesions in vitro; co-infection with GTP + PPR vaccine strains inhibited the replication of PPR vaccine strains, while the co-infection of GTP followed by PPR infection enhanced the replication of GTP vaccine strains. Moreover, virus infection enhanced the expressions of TNF-α, IL-1β, IL-6, IL-10, IFN-α, and IFN-β.

CONCLUSIONS

Peste des petits ruminants and capripox vaccine strains interfere with each other in vivo and vitro.

Molecular phylogenetics of a recently isolated goat pox virus from Vietnam

Background

After a decade of silence, an outbreak of the contagious and Asian endemic disease, goat pox re-emerged in North Vietnam affecting more than 1800 heads with a mortality rate of 6.5%. The inevitable impact of goat pox on hide quality, breeding, chevon and milk production has resulted in a significant economic losses to the developing goat industry of Vietnam. In the act of establishing an effective control of this devastating disease, tracing the source of re-emergence via a phylogenetic study was carried out to reveal their genetic relatedness. Either skin scab or papule from the six affected provinces were collected, cultured into Vero cells followed by restricted enzyme digestion of targeted P32 gene DNA encoding. The P32 gene was then cloned and transformed into E.coli competent cells for further sequencing.

Results

The isolated sequence is deposited into GenBank under Accession No. MN317561/VNUAGTP1. The phylogenetic tree revealed high similarity of nucleotide and amino acid sequences to references goat pox strains accounting for 99.6 and 99.3, respectively. The Vietnamese strain is clustered together with currently circulating goat pox virus in China, India and Pakistan which suggested the origin of South China.

Conclusions

This Vietnam isolate is clustered together with other Asian goat pox strains indicating the dissemination of a common goat pox virus within this continent.

Experimental infection of indigenous North African goats with goatpox virus

Background

Goatpox is a viral disease caused by infection with goatpox virus (GTPV) of the genus Capripoxvirus, Poxviridae family. Capripoxviruses cause serious disease to livestock and contribute to huge economic losses. Goatpox and sheeppox are endemic to Africa, particularly north of the Equator, the Middle East and many parts of Asia. GTPV and sheeppox virus are considered host-specific; however, both strains can cause clinical disease in either goats or sheep with more severe disease in the homologous species and mild or sub-clinical infection in the other. Goatpox has never been reported in Morocco, Algeria or Tunisia despite the huge population of goats living in proximity with sheep in those countries. To evaluate the susceptibility and pathogenicity of indigenous North African goats to GTPV infection, we experimentally inoculated eight locally bred goats with a virulent Vietnamese isolate of GTPV. Two uninfected goats were kept as controls. Clinical examination was carried out daily and blood was sampled for virology and for investigating the antibody response. After necropsy, tissues were collected and assessed for viral DNA using real-time PCR.

Results

Following the experimental infection, all inoculated goats displayed clinical signs characteristic of goatpox including varying degrees of hyperthermia, loss of appetite, inactivity and cutaneous lesions. The infection severely affected three of the infected animals while moderate to mild disease was noticed in the remaining goats. A high antibody response was developed. High viral DNA loads were detected in skin crusts and nodules, and subcutaneous tissue at the injection site with cycle threshold (Ct) values ranging from 14.6 to 22.9, while lower viral loads were found in liver and lung (Ct = 35.7 and 35.1). The results confirmed subcutaneous tropism of the virus.

Conclusion

Clinical signs of goatpox were reproduced in indigenous North African goats and confirmed a high susceptibility of the North African goat breed to GTPV infection. A clinical scoring system is proposed that can be applied in GTPV vaccine efficacy studies.

Lumpy Skin Disease Is Characterized by Severe Multifocal Dermatitis With Necrotizing Fibrinoid Vasculitis Following Experimental Infection

Lumpy skin disease is a high-consequence disease in cattle caused by infection with the poxvirus lumpy skin disease virus (LSDV). The virus is endemic in most countries in Africa and an emerging threat to cattle populations in Europe and Asia. As LSDV spreads into new regions, it is important that signs of disease are recognized promptly by animal caregivers. This study describes the gross, microscopic, and ultrastructural changes that occur over time in cattle experimentally challenged with LSDV. Four calves were inoculated with wildtype LSDV and monitored for 19 to 21 days. At 7 days after inoculation, 2 of the 4 cattle developed multifocal cutaneous nodules characteristic of LSD. Some lesions displayed a targetoid appearance. Histologically, intercellular and intracellular edema was present in the epidermis of some nodules. Occasional intracytoplasmic inclusion bodies were identified in keratinocytes. More severe and consistent changes were present in the dermis, with marked histiocytic inflammation and necrotizing fibrinoid vasculitis of dermal vessels, particularly the deep dermal plexus. Chronic lesions consisted of full-thickness necrosis of the dermis and epidermis. Lesions in other body organs were not a major feature of LSD in this study, highlighting the strong cutaneous tropism of this virus. Immunohistochemistry and electron microscopy identified LSDV-infected histiocytes and fibroblasts in the skin nodules of affected cattle. This study highlights the noteworthy lesions of LSDV and how they develop over time.

Establishment of a Challenge Model for Sheeppox Virus Infection

Sheeppox virus (SPPV) together with goatpox virus and lumpy skin disease virus form the genus Capripoxvirus of the Poxviridae family. Due to their great economic importance and major impact on livelihood of small-scale farmers, OIE guidelines classify capripox viruses as notifiable diseases. In the present study, we examined pathogenesis of an Indian SPPV isolate and an Egyptian SPPV isolate in sheep. Three different infection routes were tested: (i) intravenous infection, (ii) intranasal infection and (iii) contact transmission between infected and naïve sheep. Clinical course, viremia and viral shedding as well as seroconversion were analyzed in order to establish a challenge model for SPPV infections that can be used in future vaccine studies. Next to in vivo characterization, both SPPV strains underwent next- and third-generation sequencing to obtain high quality full-length genomes for genetic characterization and comparison to already published SPPV sequences.

Experimental Infection and Genetic Characterization of Two Different Capripox Virus Isolates in Small Ruminants

Capripox viruses, with their members “lumpy skin disease virus (LSDV)”, “goatpox virus (GTPV)” and “sheeppox virus (SPPV)”, are described as the most serious pox diseases of production animals. A GTPV isolate and a SPPV isolate were sequenced in a combined approach using nanopore MinION sequencing to obtain long reads and Illumina high throughput sequencing for short precise reads to gain full-length high-quality genome sequences. Concomitantly, sheep and goats were inoculated with SPPV and GTPV strains, respectively. During the animal trial, varying infection routes were compared: a combined intravenous and subcutaneous infection, an only intranasal infection, and the contact infection between naïve and inoculated animals. Sheep inoculated with SPPV showed no clinical signs, only a very small number of genome-positive samples and a low-level antibody reaction. In contrast, all GTPV inoculated or in-contact goats developed severe clinical signs with high viral genome loads observed in all tested matrices. Furthermore, seroconversion was detected in nearly all goats and no differences concerning the severity of the disease depending on the inoculation route were observed. Conclusively, the employed SPPV strain has the properties of an attenuated vaccine strain, consistent with the genetic data, whereas the GTPV strain represents a highly virulent field strain.

Experimental evaluation of the cross-protection between Sheeppox and bovine Lumpy skin vaccines

The Capripoxvirus genus includes three agents: Sheeppox virus, Goatpox virus and Lumpy skin disease virus. Related diseases are of economic importance and present a major constraint to animals and animal products trade in addition to mortality and morbidity. Attenuated vaccines against these diseases are available, but afforded cross-protection is controversial in each specie. In this study, groups of sheep, goats and cattle were vaccinated with Romania SPPV vaccine and challenged with corresponding virulent strains. Sheep and cattle were also vaccinated with Neethling LSDV vaccine and challenged with both virulent SPPV and LSDV strains. Animals were monitored by clinical observation, rectal temperature as well as serological response. The study showed that sheep and goats vaccinated with Romania SPPV vaccine were fully protected against challenge with virulent SPPV and GTPV strains, respectively. However, small ruminants vaccinated with LSDV Neethling vaccine showed only partial protection against challenge with virulent SPPV strain. Cattle showed also only partial protection when vaccinated with Romania SPPV and were fully protected with Neethling LSDV vaccine. This study showed that SPPV and GTPV vaccines are closely related with cross-protection, while LSDV protects only cattle against the corresponding disease, which suggests that vaccination against LSDV should be carried out with homologous strain.

Epidemiology and clinico-pathological characteristics of current goat pox outbreak in North Vietnam

Background

In view of the current swine fever outbreak and the government aspiration to increase the goat population, a need arises to control and prevent outbreaks of goat pox. Despite North Vietnam facing sporadic cases of goat pox, this most recent outbreak had the highest recorded morbidity, mortality and case fatality rate. Thus, owing to the likelihood of a widespread recurrence of goat pox infection, an analysis of that outbreak was done based on selected signalment, management and disease pattern (signs and pathology) parameters. This includes examination of animals, inspection of facilities, tissue sampling and analysis for confirmation of goatpox along with questionaires.

Results

It was found that the susceptible age group were between 3 and 6 months old kids while higher infection rate occurred in those under the free-range rearing system. The clinical signs of pyrexia, anorexia, nasal discharge and lesions of pocks were not restricted to the skin but have extended into the lung and intestine. The pathogen had been confirmed in positive cases via PCR as goat pox with prevalence of 79.69%.

Conclusions

The epidemiology of the current goat pox outbreak in North Vietnam denotes a significant prevalence which may affect the industry. This signals the importance of identifying the salient clinical signs and post mortem lesions of goat pox at the field level in order to achieve an effective control of the disease.

Extended sequencing of vaccine and wild-type capripoxvirus isolates provides insights into genes modulating virulence and host range

The genus Capripoxvirus in the subfamily Chordopoxvirinae, family Poxviridae, comprises sheeppox virus (SPPV), goatpox virus (GTPV) and lumpy skin disease virus (LSDV), which cause the eponymous diseases across parts of Africa, the Middle East and Asia. These diseases cause significant economic losses and can have a devastating impact on the livelihoods and food security of small farm holders. So far, only live classically attenuated SPPV, GTPV and LSDV vaccines are commercially available and the history, safety and efficacy of many have not been well established. Here, we report 13 new capripoxvirus genome sequences, including the hairpin telomeres, from both pathogenic field isolates and vaccine strains. We have also updated the genome annotations to incorporate recent advances in our understanding of poxvirus biology. These new genomes and genes grouped phenetically with other previously sequenced capripoxvirus strains, and these new alignments collectively identified several recurring alterations in genes thought to modulate virulence and host range. In particular, some of the many large capripoxvirus ankyrin and kelch-like proteins are commonly mutated in vaccine strains, while the variola virus B22R-like gene homolog has also been disrupted in many vaccine isolates. Among these vaccine isolates, frameshift mutations are especially common and clearly present a risk of reversion to wild type in vaccines bearing these mutations. A consistent pattern of gene inactivation from LSDV to GTPV and then SPPV is also observed, much like the pattern of gene loss in orthopoxviruses, but, rather surprisingly, the overall genome size of ~150 kbp remains relatively constant. These data provide new insights into the evolution of capripoxviruses and the determinants of pathogenicity and host range. They will find application in the development of new vaccines with better safety, efficacy and trade profiles.

Detection of antibodies against Lumpy skin disease virus by Virus neutralization test and ELISA methods

Infection of cattle with lumpy skin disease virus (LSDV) is very important from the aspect of livestock production. Although it can cause significant economic losses, available serological assays are still not sufficiently efficient and reliable. A 3-day VNT was performed using Madin-Darby bovine kidney (MDBK) cell line and LSDV isolated from clinically infected cow to improve serological diagnostics of lumpy skin disease (LSD).

In total, 325 cattle sera samples were tested in order to compare the performances of VNT and ELISA. Tested samples originated from 125 cows before the occurrence of LSD in the Republic of Serbia and 200 tested samples originated from vaccinated cows. Sera samples from vaccinated cows were collected starting from the vaccination day to 4 months after vaccination. In 7 different time intervals after vaccination sampling was carried out in 20 cows originating from one herd and in 3 different time intervals in 20 cows originating from a different herd each time of sampling.

Out of 200 samples from vaccinated cows, antibodies against LSDV were detected in 68 (34%) samples by VNT, and in 60 (30%) samples by ELISA. No positive finding was detected by VNT in samples collected before the occurrence of LSD in Serbia, while one positive finding was detected in the same samples by ELISA. The first presence of antibodies in vaccinated cattle was detected by both tests 20 days after vaccination, and the largest number of animals with antibodies against LSDV was detected 30 days after vaccination.

Comparing the results obtained by VNT and ELISA, it was calculated that kappa index was 0.913. The specificity of VNT and ELISA was 100% and 99.2%, respectively. VNT is simpler to perform compared to the recommended virus neutralization test by the OIE and can improve LSD serological diagnostics with additional sensitivity testing.

VARV B22R homologue as phylogenetic marker gene for Capripoxvirus classification and divergence time dating

Sheeppox disease is associated with significant losses in sheep production world over. The sheep pox virus, the goatpox virus, and the lumpy skin disease virus cannot be distinguished by conventional serological tests. Identification of these pathogens needs molecular methods. In this study, seven genes viz. EEV maturation protein-F12L, Virion protein-D3R, RNA polymerase subunit-A5R, Virion core protein-A10L, EEV glycoprotein-A33R, VARV B22R homologue, and Kelch like protein-A55R that cover the start, middle, and end of the genome were selected. These genes were amplified from Roumanian-Fanar vaccine strain and Jaipur virulent strain, cloned, and sequenced. On analysis with the available database sequences, VARV B22R homologue was identified as a marker for phylogenetic reconstruction for classifying the sheeppox viruses of the ungulates. Further, divergence time dating with VARV B22R gene accurately predicted the sheeppox disease outbreak involving Jaipur virulent strain.

Species-specific inhibition of capripoxvirus replication by host antiviral protein kinase R

The role of interferon (IFN)‐induced protein kinase R (PKR) in capripoxvirus (CaPV)‐infected cells remains unknown. In this study, we show that CaPV infection triggered PKR and eukaryotic translation initiation factor 2 alpha (eIF2α) protein phosphorylation in a dose‐dependent manner, and that this leads to decreased CaPV replication. Overexpression of PKR compromised viral gene expression and inhibited sheeppox virus (SPPV) replication. Downregulation of PKR with siRNAs significantly decreased eIF2α phosphorylation and reduced the mRNA level of IFN‐β, which increased virus replication. In luciferase assays, species‐different CaPVs K3L proteins inhibited sheep PKR (sPKR): goatpox virus K3L strongly inhibited sPKR and goat PKR (gPKR), but SPPV K3L only partially inhibited gPKR. These results are the first to show that SPPV infection induces phosphorylation of eIF2α through PKR activation, which then results in restriction of CaPV replication. Furthermore, our data show that CaPV K3L inhibits PKR in a species‐specific manner. The results presented are consistent with the hypothesis that different levels of PKR inhibition by K3L orthologs from various viruses could potentially contribute to the host range function of K3L.

Goatpox outbreak at a high altitude goat farm of Mizoram: possibility of wild life spill over to domestic goat population

In this study, pox-like outbreaks in goat population was investigated that occurred in a high altitude goat farm located in Mizoram, a hilly state of North eastern India. The outbreak initially involved the serows, an wild animal belonging to the family Bovidae, subfamily Caprinae and genus Capricornis, the state animal of Mizoram. Later, the disease affected the domestic goat population. The disease was diagnosed on the basis of gross lesions and PCR amplification of partial P32 gene of capripox virus. The virus was isolated in vero cells. The full length P32 gene was sequenced and phylogenetic tree was constructed. It was revealed that the capripox virus isolated from the outbreak was closely related to the Chinese strain of goatpox virus at both amino acid and nucleotide level. To the authors' knowledge, this is the first report on isolation and characterization of capripoxvirus from north eastern region of India.

Seroprevalence of Capripoxvirus infection in sheep and goats among different agro-climatic zones of Odisha, India

Aim:

The study was undertaken to assess the prevalence of antibodies to Capripoxviruses among small ruminants of Odisha, India.

Materials and Methods:

A total of 500 random serum samples collected from 214 sheep and 286 goats across 10 agro-climatic zones of Odisha, were screened using whole virus antigen-based indirect ELISA for antibodies against Capripoxviruses. Results were analyzed by suitable statistical methods.

Results:

Screening of 500 serum samples showed seropositivity of 8.88% and 31.47% in sheep and goats, respectively, for Capripoxviruses. The prevalence rate according to agro-climatic zone ranged from 0% (North Eastern coastal plain zone) to 48.57% (North central plateau zone) for goat pox, and 0% (Western undulating zone and North central plateau) to 22.22% (South Eastern ghat zone) for sheep pox. The difference in prevalence rates among the various agro-climatic zones was statistically significant (p<0.05) for goats, but not for sheep. Antibody prevalence rates among various districts were recorded to be the highest in Jagatsinghpur (30%) for sheep pox and Dhenkanal (80%) for goat pox.

Conclusions:

The study revealed serological evidence of Capripoxvirus infection in sheep and goat populations in the study area, in the absence of vaccination. Systematic investigation, monitoring, and reporting of outbreaks are necessary to devise control strategies.

Development and validation of a TaqMan probe-based real-time PCR method for the differentiation of wild type lumpy skin disease virus from vaccine virus strains

Lumpy skin disease (LSD) is a transboundary viral disease of cattle with severe economic impact. Immunization of cattle with homologous live attenuated vaccines poses a number of diagnostic problems, as it has been associated with adverse reactions resembling disease symptoms. The latter hampers clinical diagnosis and poses challenges in virus identification. To this end, a duplex quantitative real-time PCR method targeting the GPCR gene was developed and validated, for the concurrent detection and differentiation of wild type and vaccine Lumpy skin disease virus (LSDV) strains. The method was evaluated in three laboratories. The evaluation included a panel of 38 poxvirus isolates/strains and the analytical characteristics of the method were determined. Amplification efficiencies were 91.3% and 90.7%, for wild type and vaccine LSDV, respectively; the limit of detection was 8 DNA copies for both targets and the inter-assay CV was 0.30% for wild type and 0.73% for vaccine LSDV. The diagnostic performance was assessed using 163 LSDV-positive samples, including field specimens and samples from experimentally vaccinated/infected animals. The method is able to confirm diagnosis in suspect cases, it differentiates infected from vaccinated animals (DIVA) and can be regarded as an important tool for effective LSD surveillance and eradication during vaccination campaigns.

Prevalence, distribution, and risk factor for sheep pox and goat pox (SPGP) in Algeria

A cross-sectional study using a tested questionnaire was carried out across Algeria between January and June 2014. Our investigation demonstrated that of the 150 flocks visited, 21 were positive for sheep pox and goat pox (SPGP) with an overall flock prevalence of 14% (95% CI 11.08-16.92%) suggesting that SPGP is endemic in Algeria. Our results showed also that the disease appears only in sheep and no case affecting goats has been reported. For the risk factor analysis, univariate analysis of variables followed by a multiple logistic regression identified steppe region (OR = 1.81, 95% CI 0.87-2.57; P = 0.037), large flocks (OR = 2. 19, 95% CI 1.02-3.36; P = 0.027), and transhumance (OR = 3.98, 95% CI 2.59-5.34; P = 0.021) as risk factors in the spread of the disease. Furthermore, our study revealed that the use of vaccination as preventive measures in the selected flocks decreased the odds for SPGP positivity by 5.78 (95% CI 2.22-9.34; P < 0.001) times compared to non vaccinated flocks. In conclusion, our findings documented an evidence of a widespread distribution and endemic establishment of the SPGP in Algerian sheep population despite the annual vaccination program. Consequently, the vaccination must cover all the Algerian sheep population to improve animal welfare and reduce economic losses associated with outbreak episodes.

Real-Time PCR Assays for the Specific Detection of Field Balkan Strains of Lumpy Skin Disease Virus

Lumpy skin disease (LSD) is an important disease of cattle which is included in the OIE list of notifiable terrestrial animal diseases because of its great economic importance. The etiological agent is the Lumpy skin disease virus (LSDV).

In the control of LSD attenuated strains of LSDV and SPPV are successfully used as vaccine strains in infected areas. In the case of vaccination policy, due to the possibility of mild or systemic post-vaccination reactions in vaccinated animals, the application of diagnostic procedures that will rapidly and specifically differentiate LSDV field strains from LSD vaccine virus strains are extremely important. Rapidity in diagnostics and disposal of infected animals is one of the key factors in the prevention of spreading the disease.

In the presented study we have described the development and validation of two real-time TaqMan-PCR assays for a rapid, sensitive and specific detection of the virulent field LSDV strain currently circulating in the Balkan Peninsula. Specificity for the field strain and exclusivity for vaccine strains was tested on 171 samples from naturally infected and vaccinated animals.

The results of this study show that both developed real-time PCR assays are more sensitive than the conventional nested PCR in detecting field LSDV strains thus enabling rapid and high-throughput detection of animals infected with field strains of LSDV.

In conclusion, both KV-2 and FLI real-time PCR assays described in this study are simple, rapid, sensitive and suitable for routine use in a diagnostic laboratory and have the potential to replace conventional nested gel-based PCR assays as the standard procedure for the detection of field strains of LSDV in clinical samples.

Goatpoxvirus ATPase activity is increased by dsDNA and decreased by zinc ion

Viral-encoded ATPase can act as a part of molecular motor in genome packaging of DNA viruses, such as vaccinia virus and adenovirus, by ATP hydrolysis and interaction with DNA. Poxviral ATPase (also called A32) is involved in genomic double-stranded DNA (dsDNA) encapsidation, and inhibition of the expression of A32 causes formation of immature virions lacking viral DNA. However, the role of A32 in goatpoxvirus genome packaging and its dsDNA binding property are not known. In this study, purified recombinant goatpoxvirus A32 protein (rA32) was examined for its dsDNA binding property as well as the effect of dsDNA on ATP hydrolysis. We found that rA32 could bind dsDNA, and its ATPase activity was significant increased with dsDNA binding. Effects of magnesium and calcium ions on ATP hydrolysis were investigated also. The ATPase activity was dramatically enhanced by dsDNA in the presence of Mg(2+); in contrast, ATPase function was not altered by Ca(2+). Furthermore, the enzyme activity of rA32 was completely blocked by Zn(2+). Regarding DNA-protein interaction, the rA32-ATP-Mg(2+) showed lower dsDNA binding affinity than that of rA32-ATP-Ca(2+). The DNA-protein binding was stronger in the presence of zinc ion. Our results implied that A32 may play a role in viral genome encapsidation and DNA condensation.

Seroprevalence of Sheep and Goat Pox, Peste Des Petits Ruminants and Rift Valley Fever in Saudi Arabia

Sheep and goat pox, peste des petits ruminants and Rift Valley fever are important diseases of small ruminant livestock. Sheep and goat pox, along with peste des petits ruminants, are endemic throughout most of Africa, Asia and the Middle East. Whereas Rift Valley fever is endemic in Africa, outbreaks in the Middle East have been reported over the past decade, including the Arabian Peninsula. Saudi Arabia is a major importer of livestock, and understanding the prevalence of these viral infections would be useful for disease control. In this study, sera from sheep and goats were collected from 3 regions in Saudi Arabia. They were evaluated for antibodies specific to sheep and goat pox, peste des petits ruminants and Rift Valley fever by virus neutralization assays. To the best of our knowledge, this is the first study to evaluate the seroprevalence of these viruses in sheep and goats.

A lumpy skin disease virus deficient of an IL-10 gene homologue provides protective immunity against virulent capripoxvirus challenge in sheep and goats

Sheep and goat pox continue to be important livestock diseases that pose a major threat to the livestock industry in many regions in Africa and Asia. Currently, several live attenuated vaccines are available and used in endemic countries to control these diseases. One of these is a partially attenuated strain of lumpy skin disease virus (LSDV), KS-1, which provides cross-protection against both sheep pox and goat pox. However, when used in highly stressed dairy cattle to protect against lumpy skin disease (LSD) the vaccine can cause clinical disease. In order to develop safer vaccines effective against all three diseases, a pathogenic strain of LSDV (Warmbaths [WB], South Africa) was attenuated by removing a putative virulence factor gene (IL-10-like) using gene knockout (KO) technology. This construct (LSDV WB005KO) was then evaluated as a vaccine for sheep and goats against virulent capripoxvirus challenge. Sheep and goats were vaccinated with the construct and the animals were observed for 21days. The vaccine appeared to be safe, and did not cause disease, although it induced minor inflammation at the injection site similar to that caused by other attenuated sheep and goat pox vaccines. In addition, no virus replication was detected in blood, oral or nasal swabs using real-time PCR following vaccination and low levels of neutralising antibodies were detected in both sheep and goats. Leukocytes isolated from vaccinated animals following vaccination elicited capripoxvirus-specific IFN-γ secretion, suggesting that immunity was also T-cell mediated. Following challenge with virulent capripoxvirus, vaccinated sheep and goats were found to be completely protected and exhibited no clinical disease. Furthermore, real-time PCR of blood samples at various time points suggested that viremia was absent in both groups of vaccinated animals, as opposed to capripoxvirus-related clinical disease and viremia observed in the unvaccinated animals. These findings suggest that this novel knockout strain of LSDV has potential as a vaccine to protect livestock against sheep pox and goat pox.

Detection and characterization of atypical capripoxviruses among small ruminants in India

Recent developments in molecular biology shed light on cross-species transmission of SPPV and GTPV. The present study was planned to characterize the capripoxviruses which were circulating in the field condition among sheep and goats using RPO30 gene-based viral lineage (SPPV/GTPV) differentiating PCR and sequencing of RPO30 and GPCR genes from clinical samples. Out of 58 scabs (35 sheep and 23 goats) screened, 27 sheep and 18 goat scabs were found positive for capripox virus infections. With the exception of one sheep and one goat scabs, all the positive samples yielded amplicon size according to host origin, i.e. SPPV in sheep and GTPV in goats. In the above two exceptional cases, goat scab and sheep scab yielded amplicon size as that of SPPV and GTPV, respectively. Further, sequencing and phylogenetic analyses of complete ORFs of RPO30 and GPCR genes from six sheep and three goat scabs revealed that with the exception of above two samples, all had host-specific signatures and clustered according to their host origin. In case of cross-species infecting samples, sheep scab possessed GTPV-like signatures and goat scab possessed SPPV-like signatures. Our study identifies the circulation of cross-infecting SPPV and GTPV in the field and warrants the development of single-strain vaccine which can protect the animals from both sheeppox and goatpox diseases.

Capripox disease in Ethiopia: Genetic differences between field isolates and vaccine strain, and implications for vaccination failure

Sheeppox virus (SPPV), goatpox virus (GTPV) and lumpy skin disease virus (LSDV) of the genus Capripoxvirus (CaPV) cause capripox disease in sheep, goats and cattle, respectively. These viruses are not strictly host-specific and their geographical distribution is complex. In Ethiopia, where sheep, goats and cattle are all affected, a live attenuated vaccine strain (KS1-O180) is used for immunization of both small ruminants and cattle. Although occurrences of the disease in vaccinated cattle are frequently reported, information on the circulating isolates and their relation to the vaccine strain in use are still missing. The present study addressed the parameters associated with vaccination failure in Ethiopia. Retrospective outbreak data were compiled and isolates collected from thirteen outbreaks in small ruminants and cattle at various geographical locations and years were analyzed and compared to the vaccine strain. Isolates of GTPV and LSDV genotypes were responsible for the capripox outbreaks in small ruminants and cattle, respectively, while SPPV was absent. Pathogenic isolates collected from vaccinated cattle were identical to those from the non-vaccinated ones. The vaccine strain, genetically distinct from the outbreak isolates, was not responsible for these outbreaks. This study shows capripox to be highly significant in Ethiopia due to low performance of the local vaccine and insufficient vaccination coverage. The development of new, more efficient vaccine strains, a GTPV strain for small ruminants and a LSDV for cattle, is needed to promote the acceptance by farmers, thus contribute to better control of CaPVs in Ethiopia.

Genetic diversity of fusion gene (ORF 117), an analogue of vaccinia virus A27L gene of capripox virus isolates

The fusion gene (ORF 117) sequences of twelve (n = 12) capripox virus isolates namely sheeppox (SPPV) and goatpox (GTPV) viruses from India were demonstrated for their genetic and phylogenetic relationship among them. All the isolates were confirmed for their identity by routine PCR before targeting ORF 117 gene for sequence analysis. The designed primers specifically amplified ORF 117 gene as 447 bp fragment from total genomic DNA extracted from all the isolates. Sequence analysis revealed a significant percentage of identity among GTPV, SPPV and between them at both nucleotide and amino acid levels. The topology of the phylogenetic tree revealed that three distinct clusters corresponding to SPPV, GTPV and lumpy skin disease virus was formed. However, SPPV Pune/08 and SPPV Roumanian Fanar isolates were clustered into GTPV group as these two isolates showed a 100 and 99.3 % identity with GTPV isolates of India at nt and aa levels, respectively. Protein secondary structure and 3D view was predicted and found that it has high antigenic index and surface probability with low hydrophobicity, and it can be targeted for expression and its evaluation to explore its diagnostic potential in epidemiological investigation in future.

Characterization of sheep pox virus vaccine for cattle against lumpy skin disease virus

Lumpy skin disease is of significant economic impact for the cattle industry in Africa. The disease is currently spreading aggressively in the Near East, posing a threat of incursion to Europe and Asia. Due to cross-protection within the Capripoxvirus genus, sheep pox virus (SPPV) vaccines have been widely used for cattle against lumpy skin disease virus (LSDV). In the Middle East and the Horn of Africa these vaccines have been associated with incomplete protection and adverse reactions in cattle post-vaccination. The present study confirms that the real identity of the commonly used Kenyan sheep and goat pox vaccine virus (KSGP) O-240 is not SPPV but is actually LSDV. The low level attenuation of this virus is likely to be not sufficient for safe use in cattle, causing clinical disease in vaccinated animals. In addition, Isiolo and Kedong goat pox strains, capable of infecting sheep, goats and cattle are identified for potential use as broad-spectrum vaccine candidates against all capripox diseases.

Peste des petits ruminants virus tissue tropism and pathogenesis in sheep and goats following experimental infection

Peste des petits ruminants (PPR) is a viral disease which primarily affects small ruminants, causing significant economic losses for the livestock industry in developing countries. It is endemic in Saharan and sub-Saharan Africa, the Middle East and the Indian sub-continent. The primary hosts for peste des petits ruminants virus (PPRV) are goats and sheep; however recent models studying the pathology, disease progression and viremia of PPRV have focused primarily on goat models. This study evaluates the tissue tropism and pathogenesis of PPR following experimental infection of sheep and goats using a quantitative time-course study. Upon infection with a virulent strain of PPRV, both sheep and goats developed clinical signs and lesions typical of PPR, although sheep displayed milder clinical disease compared to goats. Tissue tropism of PPRV was evaluated by real-time RT-PCR and immunohistochemistry. Lymph nodes, lymphoid tissue and digestive tract organs were the predominant sites of virus replication. The results presented in this study provide models for the comparative evaluation of PPRV pathogenesis and tissue tropism in both sheep and goats. These models are suitable for the establishment of experimental parameters necessary for the evaluation of vaccines, as well as further studies into PPRV-host interactions.

Differentiation of sheeppox and goatpox viruses by polymerase Chain reaction-restriction fragment length polymorphism

In the present study, the partial gene sequences of P32 protein, an immunogenic envelope protein of Capripoxviruses (CaPV), were analyzed to assess the genetic relationship among sheeppox and goatpox virus isolates, and restriction enzyme specific PCR-RFLP was developed to differentiate CaPV strains. A total of six goatpox virus (GTPV) and nine sheeppox virus (SPPV) isolates of Indian origin were included in the sequence analysis of the attachment gene. The sequence analysis revealed a high degree of sequence identity among all the Indian SPPV and GTPV isolates at both nucleotide and amino acid levels. Phylogenetic analysis showed three distinct clusters of SPPV, GTPV and Lumpy skin disease virus (LSDV) isolates. Further, multiple sequence alignment revealed a unique change at G120A in all GTPV isolates resulting in the formation of Dra I restriction site in lieu of EcoR I, which is present in SPPV isolates studied. This change was unique and exploited to develop restriction enzyme specific PCR-RFLP for detection and differentiation of SPPV and GTPV strains. The optimized PCR-RFLP was validated using a total of fourteen (n=14) cell culture isolates and twenty two (n=22) known clinical samples of CaPV. The Restriction Enzyme specific PCR-RFLP to differentiate both species will allow a rapid differential diagnosis during CaPV outbreaks particularly in mixed flocks of sheep and goats and could be an adjunct/supportive tool for complete gene or virus genome sequencing methods.

Pathology and viral antigen distribution following experimental infection of sheep and goats with capripoxvirus

Current understanding of capripoxvirus pathogenesis is limited since there have been no detailed studies examining cell tropism at well-defined intervals following infection. We undertook time-course studies in sheep and goats following inoculation of sheeppox or goatpox viruses in their respective homologous hosts, and examined tissues by light microscopy. A monoclonal antibody generated to a sheeppox virus core protein was used for immunohistochemical detection of viral antigen in tissue sections. Lesions and virus antigen were observed consistently in the skin, lung and lymph nodes. Antigen was detected at 6 and 8 days post inoculation for skin and lung, respectively, within cells which appeared to be of monocyte/macrophage lineage. In sheep skin capripoxvirus immunoreactivity was detected within previously unreported large multinucleated cells. In the lung, double immunolabelling detected the simultaneous expression of capripoxvirus antigen and cytokeratin indicating the presence of virus within pneumocytes. Lung double immunolabelling also detected the expression of capripoxvirus antigen in CD68(+) cells, confirming the presence of viral antigen within macrophages. Based on early detection of infected macrophages, dissemination of virus within the host and localization to tissues likely occurred through cells of the monocyte/macrophage lineage. Histological findings revealed similarities with both monkeypox and smallpox, thus capripoxvirus infection in sheep and goats may represent useful models with which to study strategies for poxvirus-specific virus vaccine concepts and therapeutics.

An outbreak of sheep pox associated with goat poxvirus in Gansu province of China

Three strains of Capripoxviruses (CaPVs) were isolated from an outbreak of sheep pox in Gansu province of China. They were analyzed by P32 gene-based molecular methods and a species-specific PCR based on the RPO30 gene. Two bands which are specific to goat poxvirus (GTPV) were observed after the PCR products of P32 gene were digested with the endonuclease of Hinf I. Moreover, an amplicon of 172 bp, which is specific to GTPV, was amplified from the viruses by using the RPO30 gene-based PCR. Sequence analysis of the P32 genes showed that three nucleotide bases for coding residue of aspartic acid which are located at 163-165 position of P32 gene of sheep poxvirus (SPPV) were absent, and six single nucleotide substitutions which are characteristic of GTPV were present. The viruses were genetically closer to GTPV strains and clustered into the GTPV branch of the phylogenetic tree constructed on the basis of the P32 gene. The results characterized the isolated viruses as GTPV. It is the first report of an outbreak of sheep pox associated with GTPV in China.

Real time PCR method for simultaneous detection, quantitation and differentiation of capripoxviruses

The genus Capripoxvirus (CaPV) comprises three members namely, sheep poxvirus (SPPV), goat poxvirus (GTPV) and lumpy skin disease virus (LSDV) affecting sheep, goats and cattle, respectively. CaPV infections produce similar symptoms in sheep and goats, and the three viruses cannot be distinguished serologically. Since there are conflicting opinions regarding the host specificity of CaPVs, particularly for goatpox and sheeppox viruses, the development of rapid genotyping tools will facilitate more accurate disease diagnosis and surveillance for better management of capripox outbreaks. This paper describes a species-specific, real time polymerase chain reaction (PCR), based on unique molecular markers that were found in the G-protein-coupled chemokine receptor (GPCR) gene sequences of CaPVs, that uses dual hybridization probes for their simultaneous detection, quantitation and genotyping. The assay can differentiate between CaPV strains based on differences in the melting point temperature (Tm) obtained after fluorescence melting curve analysis (FMCA). It is highly sensitive and presents low intra- and inter-run variation. This real time PCR assay will make a significant contribution to CaPV diagnosis and to the better understanding of the epidemiology of CaPVs by enabling rapid genotyping and gene-based classification of viral strains and unequivocal identification of isolates.