Vaccination Of Sheep Research Articles

PSX-29 Evaluation of a vaccine in sheep to control foot rot in the Southeast

PSX-29 Evaluation of a vaccine in sheep to control foot rot in the Southeast

Evaluation of the immunogenicity and protective efficacy of an inactivated vaccine candidate for sheep infected with ovine parainfluenza virus type 3

Respiratory diseases constitute a major health problem for ruminants, resulting in considerable economic losses throughout the world. Parainfluenza type 3 virus (PIV3) is one of the most important respiratory pathogens of ruminants. The pathogenicity and phylogenetic analyses of PIV3 virus have been reported in sheep and goats. However, there are no recent studies of the vaccination of sheep or goats against PIV3. Here, we developed a purified inactivated ovine parainfluenza virus type 3 (OPIV3) vaccine candidate. In addition, we immunized sheep with the inactivated OPIV3 vaccine and evaluated the immune response and pathological outcomes associated with OPIV3 TX01 infection. The vaccinated sheep demonstrated no obvious symptoms of respiratory tract infection, and there were no gross lesions or pathological changes in the lungs. The average body weight gain significantly differed between the vaccinated group and the control group (P < 0.01). The serum neutralization antibody levels rapidly increased in sheep post-vaccination and post-challenge with OPIV3. Furthermore, viral shedding in nasal swabs and viral loads in the lungs were reduced. The results of this study suggest that vaccination with this candidate vaccine induces the production of neutralizing antibodies and provides significant protection against OPIV3 infection. These results may be helpful for further studies on prevention and control strategies for OPIV3 infections.

Quantifying the effectiveness of brucellosis control strategies in northern China using a mechanistic and data-driven model

In recent years, with the frequent movement of livestock and related products on the Chinese mainland that have resulted in a rise in brucellosis cases in certain regions, the Chinese government has implemented “vaccination + culling” strategy to control the spread of brucellosis, but the epidemiological situation and the intensity of prevention and control measures vary from province to province, and much of the situation has not yet been reversed. Thus, it is crucial to understand and assess the combined effects of vaccination and culling on brucellosis transmission behind the data from multiple provinces and cities. In this paper, we combine an ordinary differential equation model and a deep neural network model to develop a hybrid model that not only characterizes the propagation mechanism of brucellosis, but also describes control strategies as time-varying parameters to track the dynamic evolution of brucellosis transmission under control measures with varying intensity. In addition, the real-time reproduction number is calculated and taken as an evaluation index. We then train and test the hybrid model using actual data from four provincial administrative regions in Northern China from 2010 to 2020. It is found that in Inner Mongolia, the sheep vaccination rate (θ(t)) and the culling rate of infected sheep (c(t)) have a weak effect on reducing the brucellosis transmission. In Gansu, the incomplete culling of infected sheep was the main reason for the increase in human brucellosis cases after the introduction of whole-flock vaccination in 2016. Culling and vaccination contributed to the decrease in human cases in both Xinjiang and Jilin. Prevention and control measures for human brucellosis are inadequate in Xinjiang. However, prevention and control measures for human brucellosis are inadequate, while indirect transmission of Brucella from the environment to humans and sheep poses a greater risk than direct contact with infected sheep in Jilin. The above analysis can provide theoretical foundation for decision-making on public health policies to control the pandemic.

The Development and Evaluation of a New Inactivated Vaccine against Mycoplasma capricolum subsp. capricolum.

Mycoplasma capricolum subsp. capricolum (Mcc) and Mycoplasma capricolum subsp. capripneumoniae (Mccp) are pathogens that affect large and small ruminants. Indeed, Mcc affects both sheep and goats, causing contagious agalactia (CA). Mccp affects only goats, causing contagious caprine pleuropneumonia (CCPP). CA and CCPP are mainly controlled using inactivated Mcc and Mccp vaccines. However, producing the vaccine with the Mccp strain is complex, fastidious, and costly due to the slow growth of the bacterium. In this study, we present new oil-adjuvanted and inactivated Mcc and Mccp vaccines for sheep and goats against CA and CCPP. The vaccines were evaluated for safety and efficacy using experimental infection. A serological response was observed one week after of the first vaccination of sheep and goats with Mcc and goats with Mccp. The vaccinated animals were subsequently challenged with the virulent Mcc MOR20 strain. The Mcc vaccine was demonstrated to provide robust protection when the animals were challenged with Mcc MOR20. Cross-protection against the Mcc MOR20 challenge was also obtained with the Mccp vaccine. This finding revealed, for the first time, the safety and efficacy of an inactivated Mcc vaccine against contagious agalactia and cross-protection between Mcc and Mccp strains.

Successful control of Echinococcosis in Argentina and Chile through a One Health approach, including vaccination of the sheep intermediate host.

Cystic echinococcosis control in South American countries requires a comprehensive integrative ‘One Health’ approach. While insular nations have seen successful in their elimination programmes, South American countries face persistent challenges in hostile environments, with Echinococcus granulosus s.l., posing a significant public health concern. Vaccination of intermediate hosts has demonstrated the efficacy of the EG95 vaccine in reducing transmission rates. For example, since 2009, Rio Negro Province in Argentina has added, with marked success, the EG95 vaccine to the control programme, supplementing dog deworming. The Aysen Region of Chile has also reported encouraging preliminary results in reducing cyst prevalence in vaccinated sheep after 3 years of vaccination. The challenges in aligning control strategies with socio-cultural factors, especially in indigenous communities, underlines the need for context-specific strategies. The Rio Negro programme demonstrated commendable compliance, underlining the importance of community engagement in achieving lasting success. The most promising strategies for effective echinococcosis control involved dog deworming and the routine vaccination of sheep and/or goats, underscoring the importance of sustained implementation until all grazing animals have been replaced. For lasting success, these interventions need to be combined with a robust surveillance system.

IMPROVING MCCP VACCINE IN SHEEP: NOVEL STRATEGIES FOR DEVELOPMENT, EFFICACY AND CROSS-PROTECTION

Vaccination serves as a straightforward and efficient method for preventing numerous infectious diseases in animals. One such disease is contagious caprine pleuropneumonia (CCPP), a severe lung ailment affecting small ruminants. This research aimed to create a vaccine utilizing Mycoplasma capricolum subsp. capripneumoniae (Mccp) isolated from KPK, Pakistan. The local Mccp strain was rendered inactive alongside saponin, a substance, to produce the vaccine. The viable count of Mycoplasma mycoides subsp. capripneumoniae (Mccp) was determined to be 1x108 CFU/mL from the stock culture, with an estimated protein content of 0.2g/ml. The developed vaccine underwent testing and comparison with a standard CCPP vaccine in sheep to assess safety and efficacy. Twelve experimental sheep were divided into three groups: A, B, and C. Group A received the new vaccine, group B received the standard vaccine, and group C acted as the control. Groups A and B were further split into two subsets: one remained healthy while the other fell ill. The sheep were closely monitored for any changes over a 75-day post-vaccination period. Blood samples were analyzed for antibodies, showing average antibody GMT titers of 24.3, 84.4, and 128 on days 21, 28, and 35 post-immunization. By day 35, sheep vaccinated with the new vaccine displayed the highest antibody levels. The quadratic relationship (R2) indicated that both saponized and lyophilized vaccines were influenced by the number of days by 57.4% and 55%, respectively. The new vaccine demonstrated superior efficacy in sheep compared to the standard vaccine, with saponin playing a role in its effectiveness. The study successfully deactivated Mycoplasma mycoides subsp. capripneumoniae cells with autoclaved saponin, ensuring a sterile vaccine. In vivo testing in rabbits confirmed the vaccine's safety, while serum analysis in sheep revealed protective antibody responses, with the saponized vaccine eliciting higher titers than the lyophilized version. These findings suggest the potential efficacy of the saponized vaccine against Mccp infection

Adjuvants influence the immune cell populations present at the injection site granuloma induced by whole-cell inactivated paratuberculosis vaccines in sheep.

Vaccination is the most effective tool for paratuberculosis control. Currently, available vaccines prevent the progression of clinical disease in most animals but do not fully protect them against infection and induce the formation of an injection site granuloma. The precise mechanisms that operate in response to vaccination and granuloma development, as well as the effect that adjuvants could trigger, have not been fully investigated. Therefore, this study aimed to investigate the injection site granulomas induced by two inactivated paratuberculosis vaccines, which differ in the adjuvant employed. Two groups of 45-day-old lambs were immunized with two commercially available vaccines-one (n = 4) with Gudair® and the other (n = 4) with Silirum®. A third group (n = 4) was not vaccinated and served as control. The peripheral humoral response was assessed throughout the study by a commercial anti-Mycobacterium avium subspecies paratuberculosis (Map) antibody indirect ELISA, and the cellular immune response was assessed similarly by the IFN-γ release and comparative intradermal tests. The injection site granulomas were measured during the experiment and sampled at 75 days post-vaccination (dpv) when the animals were euthanized. The tissue damage, antigen and adjuvant distribution, and the presence and amount of immune cells were then determined and assessed by immunohistochemical methods. Antibodies against Map antigens; a general macrophage marker (Iba1), M1 (iNOS), and M2 (CD204) macrophages; T (CD3), B (CD20), and γδ T lymphocytes, proteins MHC-II and NRAMP1, and cytokines IL-4, IL-10, TNF, and IFN-γ were employed. Silirum® elicited a stronger peripheral cellular immune response than Gudair®, while the latter induced larger granulomas and more tissue damage at the site of injection. Additionally, adjuvant and Map antigen distribution throughout the granulomatous inflammatory infiltrate, as well as the NRAMP1 cell expression, which is linked to antigen phagocytosis, were highly irregular. In Silirum® induced granulomas, a higher number of MHC-II and TNF-expressing cells and a lower number of M2 macrophages suggested an improved antigen presentation, which could be due to the better antigen distribution and reduced tissue damage induced by this vaccine.

Identification of a One Health Intervention for Brucellosis in Jordan Using System Dynamics Modelling

Brucellosis occurs because of a complex multisector system involving the interplay between animal production and human behavior. A better understanding of transmission dynamics helps pinpoint the most effective interventions to reduce human and animal cases. Modeling methodologies have not been applied extensively to brucellosis. This study applies system dynamics modeling to identify the interplay between the different sectors that drive disease transmission and identify One Health interventions to control brucellosis. The study applies a quantitative system dynamics modeling methodology based on a qualitative in-depth analysis of the Brucella transmission system in Jordan. The data are analyzed manually to establish causal pathways to develop a stock and flow (SF) model. The structure is examined and reviewed by key informants. Several intervention scenarios to control Brucella transmission is assessed. Brucella transmission among sheep and between farms and markets are the main drivers of human incidence. Farmers’ visits to veterinary clinics are a critical intervention point for control associated with access to vaccination. The vaccination of sheep and health education activities alone might not be an effective strategy. Testing and culling sheep is the most efficient individual control strategy for animal incidence and a combination of public and animal health strategies (One Health) is the most effective strategy to reduce human incidence. The synthesis of current knowledge through the system dynamics model enables better understanding, visualization, and interpretation of the sectors involved in Brucella transmission. There is a strong synergy between sectors; therefore, greater control might be provided by utilizing multi-sectoral relationships embedded in the system.

Genome-wide epitope mapping across multiple host species reveals significant diversity in antibody responses to Coxiella burnetii vaccination and infection.

Coxiella burnetii is an important zoonotic bacterial pathogen of global importance, causing the disease Q fever in a wide range of animal hosts. Ruminant livestock, in particular sheep and goats, are considered the main reservoir of human infection. Vaccination is a key control measure, and two commercial vaccines based on formalin-inactivated C. burnetii bacterins are currently available for use in livestock and humans. However, their deployment is limited due to significant reactogenicity in individuals previously sensitized to C. burnetii antigens. Furthermore, these vaccines interfere with available serodiagnostic tests which are also based on C. burnetii bacterin antigens. Defined subunit antigen vaccines offer significant advantages, as they can be engineered to reduce reactogenicity and co-designed with serodiagnostic tests to allow discrimination between vaccinated and infected individuals. This study aimed to investigate the diversity of antibody responses to C. burnetii vaccination and/or infection in cattle, goats, humans, and sheep through genome-wide linear epitope mapping to identify candidate vaccine and diagnostic antigens within the predicted bacterial proteome. Using high-density peptide microarrays, we analyzed the seroreactivity in 156 serum samples from vaccinated and infected individuals to peptides derived from 2,092 open-reading frames in the C. burnetii genome. We found significant diversity in the antibody responses within and between species and across different types of C. burnetii exposure. Through the implementation of three different vaccine candidate selection methods, we identified 493 candidate protein antigens for protein subunit vaccine design or serodiagnostic evaluation, of which 65 have been previously described. This is the first study to investigate multi-species seroreactivity against the entire C. burnetii proteome presented as overlapping linear peptides and provides the basis for the selection of antigen targets for next-generation Q fever vaccines and diagnostic tests.

Safety and immunogenicity of inactivated Rift Valley Fever Smithburn viral vaccine in sheep

BackgroundThe live-attenuated Rift Valley Fever Smithburn (SB) vaccine is one of the oldest products widely used in ruminants for control of RVF infections. Vaccinations with RVF Smithburn result in residual pathogenic effect and is limited for use in non-pregnant animals. Commercially available RVFV inactivated vaccines are considered safer options to control the disease. These products are prepared from virulent RVFV isolates and present occupational safety concerns. This research study evaluates the ability of an inactivated SB vaccine strain to elicit neutralising antibody response in sheep.MethodsThe RVF Smithburn vaccine was inactivated with binary ethylenimine at 37 °C. Inactivated RVFV cultures were adjuvanted with Montande™ Gel-01 and aluminium hydroxide (Al (OH)3) gel for immunogenicity and safety determination in sheep. The commercial RVF inactivated vaccine and a placebo were included as positive and negative control groups, respectively.ResultsInactivated RVFV vaccine formulations were safe with all animals showing no clinical signs of RVFV infection and temperature reactions following prime-boost injections. The aluminium hydroxide formulated vaccine induced an immune response as early as 14 days post primary vaccination with neutralising antibody titre of 1:20 and a peak antibody titre of 1:83 was reached on day 56. A similar trend was observed in the animal group vaccinated with the commercial inactivated RVF vaccine obtaining the highest antibody titre of 1:128 on day 56. The neutralizing antibody levels remained within a threshold for the duration of the study. Merino sheep vaccinated with Montanide™ Gel-01-Smithburn were characterised with overall lower immune response when compared to aluminium hydroxide vaccine emulsions.ConclusionsThese finding suggests that the inactivated RVF Smithburn vaccine strain adjuvanted with aluminium-hydroxide can be used an alternative to the products prepared from virulent RVFV isolates for protection of ruminants against the disease. The vaccine can further be evaluated for safety in pregnant ewes.

Farmers' valuation and willingness to pay for vaccines to protect livestock resources against priority infectious diseases in Ghana.

Livestock vaccination coverage rates remain low in many lower and middle income countries despite effective vaccines being commonly available. Consequently, many preventable infectious livestock diseases remain highly prevalent, causing significant animal mortalities and threatening farmers' livelihood and food security. This study sought to assess farmers' maximum willingness to pay (WTP) for contagious bovine pleuropneumonia (CBPP), and peste-des-petits-ruminants (PPR) vaccination of cattle, and sheep and goats, respectively. Overall, 350 ruminant livestock farmers were randomly selected from three districts located in the northern, middle and southern farming belts of Ghana. We implemented a double-bounded dichotomous contingent valuation experiment, where farmers indicated their WTP for vaccinating each livestock specie(s) owned at randomly assigned price points. WTP responses were analyzed using maximum likelihood estimation, and factors influencing WTP were assessed using censored regression analysis accounting for village-level clustering. Mean WTP for CBPP vaccination was USD 1.43 or Ghanaian Cedi (GHC) 8.63 (95% CI: GHC 7.08-GHC 10.19) per cattle. Mean WTP for PPR vaccination was USD 1.17 or GHC 7.02 (95% CI: GHC 5.99-GHC 8.05) per sheep, and USD 1.1 or GHC 6.66 (95% CI: GHC 5.89-GHC 7.44) per goat. WTP was positively associated with resilience, limited knowledge about vaccines (assessed prior to WTP experiment), farmland size, and male gender, after adjusting for other covariates. To attain 70% vaccination coverage in Ghana, vaccination costs should be no larger than GHC 5.30 (USD 0.88) for CBPP per cattle and GHC 3.89 (USD 0.65) and GHC 3.67 (USD 0.61), respectively, for PPR vaccines per sheep and goat. Ruminant livestock farmers in Ghana value vaccination highly, and are, on average, willing to pay vaccination costs that exceed the prevailing market prices (GHC 6 for CBPP and GHC 5 for PPR vaccination) to protect their livestock resources. To achieve 70% coverage, only minor subsidies would likely be required. These results suggest that effective disease control in these settings should be possible with appropriate distribution strategies.

Evaluation of the effectiveness of foot-and-mouth disease vaccination of animals in the buffer zone of the Republic of Armenia in 2016–2020

BackgroundFoot-and-mouth disease (FMD) is a high impact viral disease of livestock for which vaccines are extensively used for limiting the spread of infection. Armenia shares a border with both Turkey and Iran where FMD is endemic, making vaccination an important component of Armenia’s control strategy. Additionally, Armenian veterinary services utilize both passive and active monitoring for prevention control.MethodsWe sought to determine the immune status of animals vaccinated against FMD and to evaluate the effectiveness of our vaccination policy in Armenia. This was conducted in three regions including Shirak, Armavir, and Ararat Region which are located in the buffer zones that border Turkey and Iran. Through active monitoring in 2020, we studied blood serum samples from cattle and sheep using an enzyme immunoassay to determine the level of immune animals in these regions following the use of a polyvalent inactivated vaccine containing FMDV serotypes A, O, and Asia-1 that are relevant for this region. ELISA titers were assessed at 28, 90, and 180 days after vaccination in cattle of three age groups at the time of initial vaccination: 4–6 months, 6–18 months and ≥ 24 months of age with sheep of all ages.ResultsThe 3 age groups of cattle had similarly high levels of immunity with over 90% of the cattle showing a ≥ 50% protective titer 28 days after the first vaccination. By day 90, titers in cattle from the initial 4–18-month age groups dropped below 58% across the 3 serotypes and at or below 80% for the oldest cattle ≥ 24 months. Re-vaccination of cattle at 120 days did improve protective titers but never reached the level of immunity of the first vaccination. Sheep showed a similar rapid drop to less than 50% having a ≥ 50% protective titer at 90 days emphasizing the need for continual revaccination.ConclusionsThe results of this study have important implications for the current FMD vaccine policy in Armenia and improves our understanding of the rapid loss of protective titers over short periods. Since small ruminants are only vaccinated once per year and vaccination titers drop rapidly by 90 days suggests that they are vulnerable to FMD and that vaccination protocols need to be updated. Cattle should continue to be vaccinated every 3–6 months depending on their age to maintain a protective level of antibodies to protect them from FMD. More studies are needed to understand the possible role of small ruminants in the epidemiology of FMD and to evaluate revaccination at shorter intervals. These results show the concerns of rapid loss of protection to both cattle and small ruminants following 1 or more doses of commercial vaccines and that additional vaccines need to be evaluated in both groups to know how often they must be vaccinated to provide full protection. The addition of challenge studies should also be considered to better understand the level of protection as measured by serology and how it relates to protection from challenge. These results should be considered by anyone using these vaccines in cattle and sheep at longer than 3 month intervals.

Detection of immune effects of the Mannheimia haemolytica gamma irradiated vaccine in sheep.

Exposure to gamma rays from cobalt 60 (Co60) can induce a complete inactivation of Mannheimia haemolytica. The inactivated bacterial pathogen is a potential vaccine candidate for immunization of ruminants such as sheep. The subcutaneous administration of irradiated vaccine in a two-dose regimen (4.0 × 109 colony forming unit (CFU) per dose) results in no mortality in any of the vaccinated sheep during immunization and after subsequent challenge of the live bacteria of the same strain of M. haemolytica. A significant rise in serum IgG titer, detected through ELISA, is observed after the passage of two weeks from the inoculation of the first dose whereas, the peak of the mean serum antibody titer occurred after two weeks of booster dose. The vaccination does not bring significant change to the IFN-γ levels in serum. The bacterial challenge of the vaccinated sheep does not induce a further seroconversion relative to serum antibody titer. In conclusion, the vaccinated sheep are protected by the elevated IgG titer and increased levels of IL-4 (Th-2 response) compared to the non-vaccinated sheep. Radiation technology can provide the opportunity for mass production of immunologically safe vaccines against animal and zoonotic diseases. Ethics Approval by the National Research Center Ethics Committee (Trial Registration Number (TRN) no 13,602,023, 13/5/2023) was obtained.

Field evaluation of sheep pox vaccine in sheep and goat in Egypt

Field evaluation of sheep pox vaccine in sheep and goat in Egypt

PPR (koyun keçi vebası) ve mavidil aşısının merinos ırkı koyunlarda eş zamanlı uygulanabilirliğinin araştırılması

Abstract: Peste des Petits Ruminants (PPR) and Bluetongue (BT), which are among the contagious animal diseases, cause serious economic losses and are included in the notifiable diseases by the World Organization for Animal Health (WOAH). PPR and BT vaccines are widely used in countries where outbreaks occur. In this study, we aimed to examine the neutralizing antibody response of simultaneously administered PPR and BT serotype 4 vaccines in sheep. For this purpose, a study was performed under field conditions in a state-owned breeding farm. All the experimental animals were confirmed seronegative by serum neutralization test (SNT) for antibodies to the PPR virus (PPRV) and BT virus serotype 4 (BTV4). Subsequently, the experimental animals were divided into four groups. Group 1 (Group 1/PPR; lamb n=10, sheep n=10) and group 2 (Group 2/BTV4; lamb n=10, sheep n=10) were vaccinated separately with the PPR and BTV4 vaccines. Group 3 was vaccinated simultaneously with PPR and BTV4 (Group 3/PPR-BTV4; lamb n=10, sheep n=10). Group 4 was unvaccinated and served as the control. In each of the experimental groups, the vaccinations were carried out only once. Post-vaccination blood samples were collected at intervals of 1, 3, and 6 months. A total of 280 post-vaccination blood serum samples were evaluated with SNT for PPRV and BTV4 neutralizing antibodies. When the neutralizing antibody levels between the groups were compared, group 3 did not show any statistically significant difference (p&gt;0.05) from group 1 and group 2. Based on the antibody response of simultaneous vaccination, it is shown that the simultaneous vaccination could be administered on the field, and could be labor and cost-effective.

Orf virus DNA prime-protein boost strategy is superior to adenovirus-based vaccination in mice and sheep.

Contagious ecthyma (Orf), an acute and highly contagious zoonosis, is prevalent worldwide. Orf is caused by Orf virus (ORFV), which mainly infects sheep/goats and humans. Therefore, effective and safe vaccination strategies for Orf prevention are needed. Although immunization with single-type Orf vaccines has been tested, heterologous prime-boost strategies still need to be studied. In the present study, ORFV B2L and F1L were selected as immunogens, based on which DNA, subunit and adenovirus vaccine candidates were generated. Of note, heterologous immunization strategies using DNA prime-protein boost and DNA prime-adenovirus boost in mice were performed, with single-type vaccines as controls. We have found that the DNA prime-protein boost strategy induces stronger humoral and cellular immune responses than DNA prime-adenovirus boost strategy in mice, which was confirmed by the changes in specific antibodies, lymphocyte proliferation and cytokine expression. Importantly, this observation was also confirmed when these heterologous immunization strategies were performed in sheep. In summary, by comparing the two immune strategies, we found that DNA prime-protein boost strategy can induce a better immune response, which provides a new attempt for exploring Orf immunization strategy.

Efficacy of leptospirosis vaccination in small ruminants: Systematic review and meta-analysis

Leptospirosis is an important cosmopolitan disease related to public health and livestock, and it has a negative influence on animals’ reproduction and productive potential. Vaccination is one of the important tools for preventing disease outbreaks, although its use among small ruminants is still insufficient. The objective of the present study was to conduct a systematic review and meta-analysis on studies that evaluated the efficacy of leptospirosis vaccines in sheep and goats. The searches in electronic databases and the process of screening and selection of material yielded nine scientific articles that reported on studies only in the sheep species. Among these articles, five presented sufficient data for a meta-analysis to be performed. These five articles reported on eight different studies evaluating the efficacy of bacterin vaccine as a way to prevent renal colonization by Leptospira spp., after experimental challenge or natural infection by the Hardjo and/or Pomona and Guaricura serovars. The meta-analytical combination resulted in a relative risk (RR) of 0.23 (95% CI: 0.09–0.55), thus indicating that vaccination was a protective factor against renal colonization and urinary shedding of Leptospira spp. Although the result from the meta-analysis indicated that vaccination was effective, the small number of studies prevented a more careful evaluation of the use of bacterins against leptospirosis in sheep. Nonetheless, this result provides encouragement for vaccination of flocks in regions with high prevalence rates of this disease, in an attempt to reduce reproductive losses. Moreover, it stimulates further research on vaccines and vaccination against leptospirosis among small ruminants, especially through use of serovars that are more prevalent in certain areas or regions.

Comparative protection of small ruminants against Mannheimia haemolytica infection by inactivated bacterin and toxoid vaccines.

Mannheimia haemolytica causes respiratory infection and mortality in sheep and goats, similar to the effects in cattle, which causes major economic damage. Regular vaccinations alongside good management practices remain the most efficient tools for controlling this disease. Indeed, vaccines against pasteurellosis are available, but results on their efficacy have varied. Therefore, this study aimed to evaluate the efficacy of three vaccines against mannheimiosis in small ruminants. We evaluated three vaccines developed from a local field isolate based on the inactivated bacterium, its toxoid, and a mixture of bacterin/toxoid, which we then tested on sheep and goats. Selected criteria that were evaluated were safety, antibody response, and protection through a challenge. Post-vaccination monitoring was carried out by enzyme-linked immunosorbent assay. The evaluation was based on antibody responses to vaccination in sheep and goats for both bacteria and leukotoxin. Protection was assessed by clinical and lesion scores after the challenge of vaccinated goats with a pathogenic strain. The three tested vaccines were completely safe, did not cause any adverse reactions, and induced significant antibody titers in immunized animals. Following M. haemolytica challenge, unvaccinated goats showed clinical signs with lesions typical of the disease. Meanwhile, the best protection was obtained with the inactivated combined bacterin/toxoid vaccine. This study highlighted the effectiveness of adding a bacterial toxoid in the vaccine as a promising solution for preventing mannheimiosis in small ruminants. Because of the worldwide distribution of M. haemolytica infection, general prophylaxis based on a combined inactivated vaccine could greatly benefit.

Investigation of the effect of mutual vaccination with pest des petits ruminants and polyvalent foot and mouth disease vaccines on the immune response of sheep.

Pest des petits ruminants (PPRs) and foot and mouth disease (FMD) are two viral infectious diseases affecting sheep dramatically causing great economic losses. Therefore, attention should be directed toward their control, especially through the application of well-designed vaccination schedules with specific potent vaccines. Determination of the possibility of sheep vaccination with PPR and FMD vaccines in a mutual schedule. Different groups of sheep have vaccinated with live attenuated PPR vaccine and inactivated polyvalent FMD vaccine in a mutual manner (one before the other at weekly intervals or simultaneously) followed by monitoring of the induced immunity to both vaccines using serum neutralization test (SNT) and enzyme linked immune sorbent assay (ELISA). SNT and ELISA revealed that there was no antagonizing effect of any vaccine on the immune response to the mutual vaccination of sheep to the other where the obtained antibody titers in single vaccinated sheep groups were similar to those in the simultaneous vaccinated group. Simultaneous vaccination of sheep with PPR and polyvalent FMD vaccine is of applicable benefit saving time, effort, and stress factors on the animals.

Detection of immunity in sheep following anti-rabies vaccination.

Rabies is a fatal but preventable disease with proper pre-exposure anti-rabies vaccination (ARV). Dogs, as household pets and strays, are the reservoir and vector of the disease, and dog bites have been associated with human rabies cases in Sri Lanka over the past few years. However, other susceptible species having frequent contact with humans may be a source of infection. One such species is sheep and immunity following ARV has never been tested in sheep reared in Sri Lanka. We have tested serum samples from sheep reared in the Animal Centre, Medical Research Institute of Sri Lanka for the presence of anti-rabies antibodies following ARV. Sheep serum samples were tested with Bio-Pro Rabies enzyme-linked immunosorbent assay (ELISA) antibody kits used for the first time in Sri Lanka and our results were verified by a seroneutralization method on cells (fluorescent antibody virus neutralization, FAVN test) currently recommended by World Organization for Animal Health and World Health Organization. Sheep received annual ARV and maintained high neutralizing antibody titers in their serum. No maternal antibodies were detected in lamb around 6 months of age. Agreement between the ELISA and FAVN test, i.e., coefficient concordance was 83.87%. Annual vaccination in sheep has an effect on maintaining adequate protection against rabies by measurements of anti-rabies antibody response. Lambs need to be vaccinated earlier than 6 months of age to achieve protective levels of neutralizing antibodies in their serum. Introducing this ELISA in Sri Lanka will be a good opportunity to determine the level of anti-rabies antibodies in animal serum samples.