Mining gene expression data for rational identification of novel drug targets and vaccine candidates against the cattle tick, Rhipicephalus microplus

Control of complex parasites via vaccination remains challenging, with the current combination of vaccines and small drugs remaining the choice for an integrated control strategy. Studies conducted to date, are providing evidence that multicomponent vaccines will be needed for the development of protective vaccines against endo- and ectoparasites, though multicomponent vaccines require an in-depth understanding of parasite biology which remains insufficient for ticks. With the rapid development and spread of acaricide resistance in ticks, new targets for acaricide development also remains to be identified, along with novel targets that can be exploited for the design of lead compounds. In this study, we analysed the differential gene expression of Rhipicephalus microplus ticks that were fed on cattle vaccinated with a multi-component vaccine (Bm86 and 3 putative Bm86-binding proteins). The data was scrutinised for the identification of vaccine targets, small drug targets and novel pathways that can be evaluated in future studies. Limitations associated with targeting novel proteins for vaccine and/or drug design is also discussed and placed into the context of challenges arising when targeting large protein families and intracellular localised proteins. Lastly, this study provide insight into how Bm86-based vaccines may reduce successful uptake and digestion of the bloodmeal and overall tick fecundity.

[The lipidosis in the liver of the dairy cow: Part 2 Genetic predisposition and prophylaxis]

Hepatic lipidosis in dairy cows is the result of a disturbed balance between the uptake of non-esterified fatty acids (NEFA), their metabolism in the hepatocytes, and the limited efflux of TG as very-low-density lipoprotein (VLDL). Lipidosis and the associated risk for ketosis represents a consequence of selecting dairy cows primarily for milk production without considering the basic physiological mechanisms of this trait. The overall risk for lipidosis and ketosis possesses a genetic background and the recently released new breeding value of the German Holstein Friesian cows now sets the path for correction of this risk and in that confirms the assumed genetic threat. Ectopic fat deposition in the liver is the result of various steps including lipolysis, uptake of fat by the liver cell, its metabolism, and finally release as very-low-density lipoprotein (VLDL). These reactions may be modulated directly or indirectly and hence, serve as basis for prophylactic measures. The pertaining methods are described in order to support an improved understanding of the pathogenesis of lipidosis and ketosis. They consist of feeding a glucogenic diet, restricted feeding during the close-up time as well as supplementation with choline, niacin, carnitine, or the reduction of milking frequency. Prophylactic measures for the prevention of ketosis are also included in this discussion.

Efficacy of hydroethanolic extract of Randia aculeata seed against the southern cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) on naturally infested cattle under field conditions

The cattle tick Rhipicephalus (Boophilus) microplus is a major problem of concern for cattle industry in tropical and subtropical areas. Control of cattle tick is based mainly on the use of chemical acaricides, which has contributed to the emerging problem of selection of resistant tick lineages. Plants have been used as an alternative to conventional acaricidal drugs. On the other hand, the acaricidal activity of hydroethanolic extract of Randia aculeata seed (EHRA) has been demonstrated against R. microplus under laboratory conditions. However, the utility of EHRA seed as a potential acaricidal needs to be determined under field conditions. For this reason, the aim of this study was to evaluate the efficacy of the EHRA against R. microplus sprayed on naturally infested calves, determine the effect of the EHRA seed on acetylcholinesterase activity in R. microplus larval and identify the chemical composition of EHRA. Forty-five male calves were divided in three groups and treated with: G1 water; G2 EHRA 20% w/v and G3 coumaphos 0.2% v/v. Acetylcholinesterase (AChE) activity in R. microplus larvae was determined by a colorimetric assay. The chemical composition of EHRA was accessed through HPLC/MS. Significantly fewer ticks were observed after 24 h on the treated group compared to control group. EHRA significantly inhibited in vitro AChE activity in R. microplus at all tested concentrations. Chlorogenic acid, vanillinic acid, p-coumaric acid, caffeic acid. rutin, quercetin, (-)-epicatechin, 4-hydroxybenzoic acid, quercetin, vanillin, 2,4-dimethoxy-6-methylbenzoic acid, scopoletin and ferulic acid were identified in the extract. The results provided new data for the elucidation of the mechanisms of EHRA acaricide action and to further evaluate the use as a new alternative control agent against R. microplus under in vivo conditions.

Modeling the effects of farming practices on bovine respiratory disease in a multi-batch cattle fattening farm

Bovine Respiratory Disease (BRD) affects young bulls, causing animal welfare and health concerns as well as economical costs. BRD is caused by an array of viruses and bacteria and also by environmental and abiotic factors. How farming practices influence the spread of these causal pathogens remains unclear. Our goal was to assess the impact of zootechnical practices on the spread of three causal agents of BRD, namely the bovine respiratory syncytial virus (BRSV), Mannheimia haemolytica and Mycoplasma bovis. In that extent, we used an individual based stochastic mechanistic model monitoring risk factors, infectious processes, detection and treatment in a farm possibly featuring several batches simultaneously. The model was calibrated with three sets of parameters relative to each of the three pathogens using data extracted from literature. Separated batches were found to be more effective than a unique large one for reducing the spread of pathogens, especially for BRSV and M.bovis. Moreover, it was found that allocating high risk and low risk individuals into separated batches participated in reducing cumulative incidence, epidemic peaks and antimicrobial usage, especially for M. bovis. Theses findings rise interrogations on the optimal farming practices in order to limit BRD occurrence and pave the way to models featuring coinfections and collective treatments p { line-height: 115%; margin-bottom: 0.25 cm; background: transparent}a:link { color: #000080; text-decoration: underline}a.cjk:link { so-language: zxx}a.ctl:link { solanguage: zxx}.

Graduate Student Literature Review: The problem of calf mortality on dairy farms

Calf mortality can be used as an indicator of animal health and welfare on dairy farms. However, several challenges surround the estimation and reporting of this metric, specifically: (1) lack of records or reliable data, (2) methods of data collection, and (3) inconsistencies in calculation and definitions used. Therefore, despite its importance, the lack of consensus on a definition of calf mortality makes it difficult to compare mortality rates between dairy farms or studies. Monitoring factors associated with calf mortality is vital to create preventative strategies. Although common strategies have been set about how to raise dairy calves and manage dairy calves, discrepancies among studies evaluating factors associated with calf mortality still exist. This review summarizes research on the evaluation of calf mortality and associated risk factors, specifically, the lack of reliable data and standardization of the definition of calf mortality. In addition, current strategies to monitor and prevent calf mortality will be presented in this review.

Dynamics of Extended-spectrum Beta-lactamase-producing, Third-generation Cephalosporin-resistant and Tetracycline-resistant Escherichia coli in Feedlot Cattle With or Without Tylosin Administration

The impact of in-feed use of tylosin in feedlot cattle on Gram-negative foodborne bacteria is unknown. We evaluated the effect of continuous in-feed tylosin use on the concentration and prevalence of tetracycline-resistant (TETr)-, third-generation cephalosporin-resistant (3GCr)-, and extended-spectrum β-lactamase-producing (ESBLs) E. coli in feedlot cattle. A cohort of weaned calves (10 animals/group) were randomized to receive a feed ration with or without tylosin. Fecal samples, regularly collected over the entire feeding period, and pen surface and feed samples, collected at the end of the feeding period, were cultured on selective media. Enumeration and binary outcomes were analyzed by mixed effects linear regression or logistic regression, respectively, using treatment and days on feed as fixed factors, and animal ID as a random variable. Tylosin supplementation did not affect the fecal concentrations of TETrE. coli or fecal prevalence of 3GCrE. coli. However, cattle in the tylosin group were 1.5 times more likely (Odds ratio = 1.5: 95% confidence interval: 1.1-2.0) to harbor ESBLs E. coli than the control cattle. Regardless of tylosin treatment, fecal concentrations of TETrE. coli and the prevalence of 3GCr- and ESBLs-E. coli increased over time. Tylosin-supplemented feed did not affect the prevalence of TETrE. coli; 3GCr and ESBLs-E. coli were not detected from the feed samples. Most of the 3GCr- and ESBLs-E. coli isolates carried the blaCTX-M-15 gene, widely detected among ESBLs-E. coli human isolates. In summary, although in-feed tylosin use in feedlot cattle did not select for TETr- and 3GCr-E. coli, it increased the likelihood of detecting ESBL-producing E. coli. Furthermore, the study indicated that the feedlot production setting gradually increases the levels of E. coli resistant to the critically and/or important antibiotics for public health, indicating an increased risk of their dissemination beyond the feedlot environment.

Unravelling transmission of Mycobacterium avium subspecies paratuberculosis to dairy calves: results of a lifelong longitudinal study

Johne's disease (JD) is a chronic disease of ruminants endemic in the UK and other countries and responsible for large economic losses for the dairy sector. JD is caused by Mycobacterium avium subspecies paratuberculosis (MAP), which typically infects calves that remain latently infected during a long period, making early detection of infection challenging. Cow to calf transmission can occur in-utero, via milk/colostrum or faecal-orally. Understanding of the different transmission routes to calves is important in informing control recommendations. Our aim in this longitudinal study was to measure the association between the transmission routes via the dam and the environment on a calf subsequently testing serologically positive for MAP. The study population comprised of 439 UK dairy calves from 6 herds enrolled between 2012 and 2013. These calves were followed up from birth until 2023. At birth individual calf data was captured. During follow-up, individuals entering the milking herd were quarterly tested for the presence of MAP antibodies using milk ELISA. Cox regression models were used to measure the association between exposure from the dam (in-utero and/or colostrum) or from the environment (long time in dirty yard) and time to first detection of MAP infection. An association between calves born to positive dams and probability of having a MAP positive test result remained after excluding potential MAP transmission via colostrum (Hazard ratio: 2.24; 95% CI: 1.14 - 4.41). Calves unlikely to be infected with MAP via the in-utero or colostrum route, had 3.68 (95% CI: 3.68 1.45-9.33) higher hazard of a positive test result when they stayed longer in a dirty calving area. The effect of the dam infection status on transmission to calves precedes the dam's seroconversion and persists after excluding the potential role of transmission via colostrum. The association between time spent in a dirty calving area and probability of a MAP positive test result highlights the role of environmental contamination as a source of infection in addition to the dam.

First report of the efficacy of a fluralaner-based pour-on product (Exzolt® 5%) against ectoparasites infesting cattle in Brazil

BACKGROUND

This study describes the effectiveness of a novel active pharmaceutical ingredient, fluralaner (isoxazoline class), against important ectoparasites infesting cattle in Brazil.

METHODS

A total of 13 studies involving a 5% fluralaner-based pour-on formulation (Exzolt 5%; further referred to as Exzolt) were conducted. Specifically, the effectiveness of this formulation was studied against Rhipicephalus microplus (6 studies), Cochliomyia hominivorax larvae (4 studies), Dermatobia hominis larvae (1 study) and Haematobia irritans flies (2 studies).

RESULTS

The therapeutic efficacy of Exzolt was found to exceed 98% at 4 days post treatment (DPT), while persistent efficacy (> 90% efficacy) against repeated infestations of R. microplus was observed for up to 79 DPT. In field studies, ≥ 98% therapeutic efficacy was demonstrated at all study sites by 7 DPT, and a persistent efficacy (> 90% efficacy) was observed for 42, 49 or 56 DPT. Exzolt prevented C. hominivorax eggs from developing to the larval stage, thus mitigating the development of myiasis in cattle naturally and artificially infested with this screworm. The efficacy of Exzolt against D. hominis larvae was 98% at 3 DPT, while persistent efficacy (> 90% effectiveness) was found to last for up to 70 DPT. Against H. irritans, Exzolt showed therapeutic efficacy (≥ 90%) within the first day of treatment at both study sites, while persistent efficacy (≥ 90%) was observed for 7 DPT at one site and for 21 DPT at the other site.

CONCLUSIONS

Overall, the results from these studies confirm that Exzolt is therapeutically efficacious against the most important ectoparasites infesting cattle in Brazil. The novel active pharmaceutical ingredient, fluralaner, provides a new treatment option for farmers to control cattle ectoparasites, especially where there is resistance to other chemical classes. In addition, an effective control of ectoparasites will improve overall cattle health and well-being as well as production.

Effect of a preventive strategic control program, with imidocarb dipropionate, against tick fever agents in dairy calves

Chemoprophylaxis with dipropionate imidocarb (IMD) is a method adopted to prevent cattle tick fever (TF). Sixty weaned dairy heifers (±60 days old), without previous exposure to Rhipicephalus microplus ticks, were housed in Tifton paddocks and were subsequently exposed to R. microplus ticks and monitored up to 315 days old. Thirty animals were kept as controls (T01) and 30 received five preventive strategic treatments with IMD at 21-day intervals (T02). The heifers were monitored weekly by means of packed cell volume (PCV) and blood smears to evaluate the presence of TF agents. Salvage treatments (ST) with diminazene and enrofloxacin were administered when animals showed PCV ≤ 24%. The A. marginale prevalence was 39.3% and 37.7%, B. bovis 6.0%, and 7.3%, and B. bigemina 16.3% and 13.7% for T01 and T02, respectively. Regarding PCV values, group T01 showed lower PCV than group T02, between 119 and 161 days of life, but when animals were 196, 210, 217, and between 252 to 301 days old, an inversion occurred. The IMD treatment protocol was effective in group T02 from day 91 to 175 while treatment was being administered, but from day 182 to 315 after the IMD treatment protocol was completed, the number of salvage treatments against TF agents performed in T02 group increased significantly. The sequential application of IMD treatments with intervals less than 21 days is not recommended.

Immuno-bioinformatic approach for designing of multi-epitope merozoite surface antigen of Babesia bigemina and evaluation of its immunogenicity in inoculated calves

Babesiosis is a parasitic disease caused by intraerythrocytic parasites of the genus Babesia, which infect both wild and domestic animals. Merozoite surface antigens (MSAs) have been identified as efficient immunogens in Babesia-infected animals. MSAs play a key role in the invasion process and have been proposed as potential targets for vaccine development. Epitope-based vaccines offer several advantages over whole protein vaccines as the immunogenic proteins are small and can induce both Th1 and Th2 immune responses, which are desirable for protection. However, the MSA, particularly gp45, is polymorphic in Babesia bigemina, posing a challenge to vaccine development. The purpose of this study was to develop a recombinant gpME (gp45-multi-epitope) for a vaccine against Babesia bigemina. B-cell, T-cell, and HLA epitope predictions were used to synthesize the gpME sequence from the consensus sequence of gp45. The gpME sequence was synthesized and cloned in the pET28α vector through the commercial biotechnology company to get pET28-gpME. The plasmid cloned with the gpME sequence comprising 1068 bp was expressed in a bacterial expression system. A band of 39 kDa of rec-gpME was obtained via SDS-PAGE and Western blotting. Rec-gpME @200ng was injected in calves 3 times at 2 weeks interval. The humoral response was evaluated through the indirect ELISA method. The ELISA with rec-gp45 protein showed a significant value of optical density. The recombinant protein containing multiple epitopes from the MSA gp45 may represent a promising candidate for a vaccine against Babesia bigemina.

Invited review: Bovine neonatal morbidity and mortality-Causes, risk factors, incidences, sequelae and prevention

The neonatal period may be defined as the first month of the calf's life; it may be considered part of the fourth trimester. It is the most hazardous due to the immaturity of the neonate's immune system and the environmental challenge from infections, the main causes of both bovine neonatal morbidity and mortality. The five most common morbidities causing mortality in neonatal calves are, in descending order, gastrointestinal infections, respiratory infections, abomasal disorders, umbilical infections and developmental abnormalities. This review describes the aetiology, incidence, risk factors and sequelae of these common morbidities and highlights current preventive strategies both at farm and national levels.

Persistence of orthopaedic hoof blocks for the treatment of lame cattle kept permanently at pasture

AIMS

To compare the retention by New Zealand dairy cows kept at pasture in a lame cow group, of three hoof block products commonly used in the remediation of lameness.

METHODS

Sixty-seven farmer-presented Friesian and Friesian x Jersey dairy cows from a single herd in the Manawatū region (New Zealand) suffering from unilateral hind limb lameness attributable to a claw horn lesion (CHL) were randomly allocated to one of three treatments: foam block (FB), plastic shoe (PS) and a standard wooden block (WB). Blocks were applied to the contralateral healthy claw and checked daily by the farm staff (present/not present) and date of loss was recorded. Blocks were reassessed on Day 14 and Day 28 and then removed unless further elevation was indicated. Daily walking distances were calculated using a farm map and measurement software. Statistical analyses included a linear marginal model for distance walked until block loss and a Cox regression model for the relative hazard of a block being lost.

RESULTS

Random allocation meant that differences between products in proportion used on left or right hind foot or lateral or medial claw were small. Mean distance walked/cow/day on farm tracks whilst the block was present was 0.32 (min 0.12, max 0.45) km/day; no biologically important difference between products in the mean distance walked was identified. Compared to PS, cows in the WB group were five times more likely to lose the block (HR = 4.8 (95% CI = 1.8-12.4)), while cows in the FB group were 9.5 times more likely to lose the block (HR = 9.5 (95% CI = 3.6-24.4)).

CONCLUSIONS

In this study, PS were retained for much longer than either FB or WB. As cows were managed in a lame cow group for the study duration, walking distances were low and did not impact on the risk of block loss. More data are needed to define ideal block retention time.

CLINICAL RELEVANCE

In cows with CHL the choice of block could be based on the type of lesion present and the expected re-epithelisation times.

Quantitative risk assessment of FMDV introduction in a FMD free country through bone-in beef and offal importation from a FMD free with vaccination country/zone

Quantitative risk assessment was used to estimate the risk of introducing foot-and-mouth disease (FMD) through bone-in beef from Argentina (FMD-free with vaccination status) into other FMD-free countries. A stochastic model was built to characterize all the steps from primary production to bone-in beef export and introduction into an FMD-free country. The probability that bone-in beef from at least one animal infected with the FMD virus (FMDV) was exported during a year was 5.27 × 10-3 (95% CI <10-10 - 5.19 x 10-2) or in other words one case in 190 years. The risk of FMDV introduction was sensitive to the probability of an outbreak occurring in Argentina (r [Spearman´s rank correlation] = 0.99) and the number of herds affected during an outbreak (r = 0.10). Additionally, the probability that susceptible animals in the importing country came into contact with infective material (bones) and generated an outbreak was 6.16 × 10-4 (95% CI <10-10 - 6.20 ×10-3) or one FMD outbreak every 1623 years on average. Based on the quantitative risk assessment results, the probability of FMDV introduction into a FMD-free country where vaccination is not practiced from a FMD-free country where vaccination is practiced associated with bone-in beef trade from Argentina was negligible. The risk of an FMD outbreak caused by the potential introduction of the FMDV was associated with the existing conditions in the country. Thus, maintaining the FMD-free status with or without vaccination would not be relevant.

Selective versus strategic control against Rhipicephalus microplus in cattle: A comparative analysis of efficacy, animal health, productivity, cost, and resistance management

This study compared selective control versus strategic control against Rhipicephalus (Boophilus) microplus, under conditions of a real dairy farm. Strategic control requires that all animals be treated with acaricide at regular pre-determined intervals. Selective control only requires treatment of infested animals and only when they are at or above a pre-determined threshold. Tick counts on animals and in pasture were performed and the susceptibility of tick populations to the different treatment methods was evaluated at the beginning and end of the study using the Larval Packet Test, Larval Immersion Test, and Adult Immersion Test. Over the four years of the study strategic control was more advantageous than the selective control as the group experienced lower tick burden on animals and in pasture, absence of skin lesions and myiases, lower operating costs, treatments concentrated in fewer months of the year and lower resistance pressure.

Knowledge, attitudes and biosecurity practices among the small-scale dairy farmers in Sylhet district, Bangladesh

BACKGROUND

In the context of zoonosis, Bangladesh's small-scale dairying is yet to frame satisfactory levels due to poor biosecurity practices.

OBJECTIVES

This study intended to reveal the degree of knowledge, attitudes and biosecurity practices among Sylhet district, Bangladesh's small-scale dairy farmers. We also focused on the association between biosecurity practices and the incidence of non-specific enteritis in humans.

METHODS

A questionnaire-based survey was conducted on the farmers' KAP via personal interviews of 15 farmers from the randomly selected fifteen small-scale dairy farms. The questionnaire was developed with 6 questions for knowledge, 6 questions for attitude and 12 questions for the practice of biosecurity measures. Alongside that, data on the number of non-specific enteritis cases experienced by the farmers or their family members were also recorded. Spearman correlation was used to find out the correlation among KAP variables and between practice scores and non-specific enteritis incidences.

RESULTS

We found an insignificant (p > 0.05) influence of demographic characteristics over knowledge, attitude and biosecurity practices. Significant (p < 0.05) and strong correlations were found in knowledge-attitude (r = 0.65), knowledge-practice (r = 0.71) and attitude-practice (r = 0.64). Incidences of non-specific enteritis and biosecurity measures' practice were also strongly correlated (r = -0.9232) and statistically significant (p < 0.05).

CONCLUSIONS

Our study suggests that increasing knowledge and developing a good attitude are necessary to increase the adaptation of biosecurity measures as three of these factors are correlated. Moreover, farm biosecurity measures are closely related to human health.

Molecular and genetic characterization of bovine parainfluenza type 3 European field and vaccine strains

Bovine Parainfluenza Type 3 virus (BPIV-3) is an enveloped, non-segmented single-stranded, negative-sense RNA virus belonging to the Paramyxoviridae family (genus Respirovirus) with a well-known role in Bovine Respiratory Disease (BRD) onset. Being isolated for the first time in 1959, BPIV-3 currently circulates worldwide in cattle herds and is routinely tested in suspected BRD cases. Different commercial vaccines are available to prevent infection and/or to reduce the clinical signs associated with BPIV-3 infection, which are essential to prevent secondary infections. Despite years of molecular surveillance, a very limited number of complete genome sequences were made publicly available, preventing thus the understanding of the genetic diversity of the circulating strains in the field. In addition, no data about the genetic identity between field and vaccine strains is currently available. In this study, we sequenced the full-genome and genetically characterized BPIV-3 strains isolated from animals displaying respiratory illness in France and Sweden, as well as the vaccine strains contained in three different commercialized vaccines. Our results show that the sequences from France and Sweden belong to genotype C. However, a third sequence from Sweden from 2017 clustered within genotype A. The sequencing of vaccine strains revealed that two of the vaccine strains clustered within genotype C, whereas the third vaccine strain belonged to genotype A. Altogether, our findings suggest that both genotypes A and C circulate in Europe and that BPIV-3 field and vaccine strains are genetically divergent. Our sequencing results could be useful to better understand the genetic differences between the circulating field and vaccine BPIV-3 strains. This is crucial for a correct interpretation of diagnostic findings and for the assessment of BPIV-3 prevalence in cattle population.

A participatory approach to understand the attitudes and perceptions towards priority endemic cattle diseases among dairy farmers and animal health experts in Henan province, China

The dairy industry is threatened by a variety of endemic diseases and emerging diseases, and various control programs have been initiated in China. The increased application of evidence to policymaking can help improve the efficiency of disease control programs; however, the relevant research literature is currently lacking. The objective of this study was to gain an in-depth understanding of the attitudes and perceptions towards priority endemic diseases among dairy farmers and animal health experts by taking Henan province of China as the example and using semi-structured interviews and focus group discussions, respectively. This study involved 24 farmers and 27 animal health experts from December 2019 to January 2021. The diseases considered by farmers to be of significance to their animals are different from those considered priorities by the participating experts and the government list. From the perspective of the individual farmers, the effects of zoonotic disease risks such as bovine brucellosis and tuberculosis appear to be less pronounced than "visible" losses at the farm level, contrary to the opinion of experts. Participating experts believed that poor on-farm biosecurity measures posed challenges to the control and eradication of priority endemic diseases; however, there are gaps in farmers' understanding of biosecurity principles, and low motivations to take such disease prevention measures. Several other challenges to the control and eradication of priority endemic diseases also emerged in the data, including the lack of diagnostic tools applicable in the field as well as differential diagnostic tools to differentiate natural infection from vaccination, lack of effective and commercially available vaccines against single or multiple pathogen(s) or new genotypes/serotypes, weak early warning and information networks and insufficient economic compensation. A holistic understanding of people's perceptions of disease control would facilitate the implementation of inclusive and engaging disease control strategies, thereby increasing the efficiency of disease control.

Development of a spore-based mucosal vaccine against the bovine respiratory pathogen Mannheimia haemolytica

Bovine respiratory disease (BRD) is a significant health issue in the North American feedlot industry, causing substantial financial losses due to morbidity and mortality. A lack of effective vaccines against BRD pathogens has resulted in antibiotics primarily being used for BRD prevention. The aim of this study was to develop a mucosal vaccine against the BRD pathogen, Mannheimia haemolytica, using Bacillus subtilis spores as an adjuvant. A chimeric protein (MhCP) containing a tandem repeat of neutralizing epitopes from M. haemolytica leukotoxin A (NLKT) and outer membrane protein PlpE was expressed to produce antigen for adsorption to B. subtilis spores. Adsorption was optimized by comparing varying amounts of antigen and spores, as well as different buffer pH and reaction temperatures. Using the optimal adsorption parameters, spore-bound antigen (Spore-MhCP) was prepared and administered to mice via two mucosal routes (intranasal and intragastric), while intramuscular administration of free MhCP and unvaccinated mice were used as positive and negative control treatments, respectively. Intramuscular administration of MhCP elicited the strongest serum IgG response. However, intranasal immunization of Spore-MhCP generated the best secretory IgA-specific response against both PlpE and NLKT in all samples evaluated (bronchoalveolar lavage, saliva, and feces). Since proliferation of M. haemolytica in the respiratory tract is a prerequisite to lung infection, this spore-based vaccine may offer protection in cattle by limiting colonization and subsequent infection, and Spore-MhCP warrants further evaluation in cattle as a mucosal vaccine against M. haemolytica.

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.

Immunogenicity of a freeze-dried combined vaccine against Rift Valley fever and bovine ephemeral fever in cattle

Background

The target of vaccination is to encourage a strong, covering and long-lasting immune response against antigens. For achieving these objectives; effective adjuvant and new vaccine strategies are demanded to make the vaccine sufficiently immunogenic to instigate a powerful immune response.

Aim

This study was completed for elaboration and evaluation of freeze-dried combined vaccine against both Rift Valley fever (RVF) and bovine ephemeral fever (BEF) viruses using different stabilizers.

Methods

Three formulae were prepared from such vaccine including: formula (1): stabilized with a mixture of 5% Lactalbumin Hydrolysate and 2.5% sucrose, formula (2): stabilized with a mixture of 50% the previous stabilizer and 50% of 1% Carbopol and formula (3): stabilized with 1% Carbopol solution. Samples of the three vaccine formulae were reconstituted on the time of experimental animal vaccination using saponin diluent which acts as an adjuvant for both RVFv and BEFv and as an inactivator BEF virus. The ratio between both viruses in all vaccine formulae was 1:1.

Results

All vaccine batches were proved to be free of any foreign contaminants and unharmed for experimentally vaccinated animals. Each of the three groups of calves was vaccinated S/C with 2 ml of a reconstituted vaccine formula and their immune response was evaluated using serum neutralization test. The gained results revealed that the prepared combined freeze-dried vaccine with Carbopol elicited a better humoral immune response than the other two vaccine formulae.

Conclusion

It could be recommended to use Carbopol as a stabilizer for the preparation of the aimed vaccine.

Putative target sites in synganglion for novel ixodid tick control strategies

Acaricide resistance is a global problem that has impacts worldwide. Tick populations with broad resistance to all commercially available acaricides have been reported. Since resistance selection in ticks and their role in pathogen transmission to animals and humans result in important economic and public health burden, it is essential to develop new strategies for their control (i.e., novel chemical compounds, vaccines, biological control). The synganglion is the tick central nervous system and it is responsible for synthesizing and releasing signaling molecules with different physiological functions. Synganglion proteins are the targets of the majority of available acaricides. In this review we provide an overview of the mode-of-action and resistance mechanisms against neurotoxic acaricides in ticks, as well as putative target sites in synganglion, as a supporting tool to identify new target proteins and to develop new strategies for tick control.

A foot and mouth disease ranking of risk using cattle transportation

Foot-and-mouth disease (FMD) is a highly infectious condition that affects domestic and wild cloven-hoofed animals. This disease has substantial economic consequences. Livestock movement is one of the primary causes of disease dissemination. The centrality properties of the livestock mobilization transportation network provide valuable information for surveillance and control of FMD. However, the same transportation network can be described by different centrality descriptions, making it challenging to prioritize the most vulnerable nodes in the transportation network. This work considers the construction of a single network risk ranking, which helps prioritize disease control measurements. Results show that the proposed ranking constructed on 2016 livestock mobilization data may predict an actual outbreak reported in the Cesar (Colombia) region in 2018, with a performance measured by the area under the receiver operating characteristic curve of 0.91. This result constitutes the first quantitative evidence of the predictive capacity of livestock transportation to target FMD outbreaks. This approach may help decision-makers devise strategies to control and prevent FMD.

Desiccant Dusts, With and Without Bioactive Botanicals, Lethal to Rhipicephalus (Boophilus) microplus Canestrini (Ixodida: Ixodidae) in the Laboratory and on Cattle

The exotic southern cattle fever tick, Rhipicephalus (Boophilus) microplus (Canestrini) (Ixodida: Ixodidae), since its eradication from the United States in 1943, made a strong incursion into Texas, beginning 2016. The pest is arguably the most economically detrimental ectoparasite of cattle, Bos taurus L., worldwide. Current R. (B.) microplus control mostly relies on conventional synthetic acaricides to which the ixodid has been developing resistance. Our study demonstrates that commercially available desiccant dust products, with and without bioactive botanical additives, are strongly lethal, when applied dry, against larval R. (B.) microplus in the laboratory, and after being released on dust-treated cattle. Deadzone (renamed Celite 610, a diatomaceous earth product), Drione (silica gel + pyrethrins + piperonyl butoxide synergist), and EcoVia (silica gel + thyme oil), each prophylactically prevented larval R. (B.) microplus from attaching to and feeding on stanchioned calves. Desiccant dust-based products are less likely than conventional synthetic acaricides to decline in terms of efficacy as a result of ixodid resistance, and other desiccant dust advantages, including extended residual, flexibility in terms of application methods, environmental, animal, and human safety, and possible compatibility with organic, or 'green', production systems, are discussed. We anticipate that the desiccant dusts we evaluated, and others not included in this study (e.g., kaolin, perlite, and silica gel) will be effective when used with other control tactics in integrated pest management approaches for controlling R. (B.) microplus (and other ixodid species).

Immune response against lumpy skin disease after simultaneous vaccination of cattle with sheep pox and goatpox and foot and mouth disease vaccines

Foot and mouth disease (FMD) and Lumpy skin disease (LSD) are contagious viral diseases that cause significant economic damage in the livestock industry of countries. Cattle are vaccinated two times a year with FMD and sheep pox and goat pox vaccines (SGP) within 30-day intervals to combat both diseases in Türkiye. However, vaccinations in different periods increase vaccination costs, labor, and distress on animals. Therefore, it was aimed to determine the effects of simultaneous vaccination of FMD and SGP vaccines on the immunity against LSD and FMD in cattle. For this purpose, animals were divided into 4 groups; SGP vaccinated group (Group 1, n = 10), FMD vaccinated group (Group 2, n = 10), FMD and SGP simultaneously vaccinated group (Group 3, n = 10), and the unvaccinated control group (Group 4, n = 6). Blood samples were collected and analyzed to detect the antibody response against the LSD via Capripoxvirus (CaPV) ELISA and FMD by Virus Neutralisation test (VNT) and Liquid Phase Blocking ELISA (LPBE). A live virus challenge study was performed to determine the immune response against LSD. The mean antibody titers were determined protective levels on 28 days post vaccination (DPV) against FMDV serotypes O and A, respectively. The logarithmic difference of skin lesions was calculated log10 titer > 2.5. LSD genome could not be detected in the blood, eyes, and nose swap samples of the challenged animals on the 15th day via PCR. In conclusion, adequate protective immune response was provided against LSD when the SGP and FMD vaccines were used simultaneously in cattle.