Deep sequencing and variant frequency analysis for the quality control of a live bacterial vaccine against contagious bovine pleuropneumonia, strain T1.

Vaccination is the most cost-effective tool to control contagious bovine pleuropneumonia. The vaccines currently used in Africa are derived from a live strain called T1, which was attenuated by passage in embryonated eggs and broth culture. The number of passages is directly correlated to the degree of attenuation of the vaccinal strains and inversely correlated to their immunogenicity in cattle. Current quality control protocols applied to vaccine batches allow the assessment of identity, purity, and titers, but cannot assess the level of genetic drift form the parental vaccine strains. Deep sequencing was used to assess the genetic drift generated over controlled in vitro passages of the parental strain, as well as on commercial vaccine batches. Signatures of cloning procedures were detected in some batches, which imply a deviation from the standard production protocol. Deep sequencing is proposed as a new tool for the identity and stability control of T1 vaccines.

Hyper-production of porcine contagious pleuropneumonia subunit vaccine proteins in Escherichia coli by developing a bicistronic T7 expression system.

The ApxII toxin and the outer membrane lipoprotein (Oml) of Actinobacillus pleuropneumoniae are important vaccine antigens against porcine contagious pleuropneumonia (PCP), a prevalent infectious disease affecting the swine industry worldwide. Previous studies have reported the recombinant expression of ApxII and Oml in Escherichia coli; however, their yields were not satisfactory. Here, we aimed to enhance the production of ApxII and Oml by constructing a bicistronic expression system based on the widely used T7 promoter. To create efficient T7 bicistronic expression cassettes, 16 different fore-cistron sequences were introduced downstream of the T7 promoter. The expression of three vaccine antigens Oml1, Oml7, and ApxII in the four strongest bicistronic vectors were enhanced compared to the monocistronic control. Further optimization of the fermentation conditions in micro-well plates (MWP) led to improved production. Finally, the production yields reached unprecedented levels of 2.43 g L-1 of Oml1, 2.59 g L-1 of Oml7, and 1.21 g L-1 of ApxII, in a 5 L bioreactor. These three antigens also demonstrated well-protective immunity against A. pleuropneumoniae infection. In conclusion, this study establishes an efficient bicistronic T7 expression system that can be used to express recombinant proteins in E. coli and achieves the hyper-production of PCP vaccine proteins.

Risk factors associated with contagious caprine pleuropneumonia in goats of Amhara region, Ethiopia.

Contagious caprine pleuropneumonia (CCPP) is a serious contagious disease of goats, sheep and wild ruminants caused by Mycoplasma capricolum subspecies capripneumoniae. The disease is known for its high mortality, morbidity and economic losses. A cross-sectional study using multistage cluster sampling technique was conducted in Amhara region from January 2019 to July 2019 to estimate seroprevalence and identify risk factors of CCPP occurrence in the region. A total of 2080 goats from 61 villages and 12 districts of the region were tested for CCPP serostatus using Competitive Enzyme-Linked Immunosorbent Assay (C-ELISA). A multilevel mixed-effect logistic regression model was used to identify risk factors of CCPP seropositivity at animal and flock-level. The serum sample results revealed an overall animal level seroprevalence of 5.1% (95% CI: 3.8-6.6) and flock-level prevalence of 26.0% (95% CI: 19.7-33.4). At individual animal level, presence of other health problems (OR = 45.9 (95% CI: 25.3-83.4)), age (adult age (OR = 6.2 (95% CI:3.4-11.4)) and old age (OR = 13.1 (95% CI: 6.2-27.8))), and breed type (Afar (OR= 32.3 (95% CI: 2.9-366.1)), Central highland (OR=13.7 (95% CI: 1.3-140.6)), and western highland (OR=16.2 (95% CI: 1.4-185.7))) were identified as risk factors for CCPP seropositivity. In contrast, contact with other flocks (OR = 59.9 (95% CI: 6.1-585.6)), presence of trade route (OR = 3.1 (95% CI: 1.0-9.1)) and presence of sheep (OR = 2.6 (95% CI: 1.2-5.7)) were flock-level risk factors for CCPP seropositivity. Generally, CCPP appears to be common among goats of Amhara region. Goat flocks dominated with older age animals; breeds of Afar, central highland, and western highland; raise with sheep; have contact with other flocks; and kept along trade routes are more at risk for CCPP. Hence, awareness creation to the producers, movement control, and regular prophylactic vaccination should be considered to control CCPP in Amhara region.

Development and Evaluation of a Combined Contagious Bovine Pleuropneumonia (CBPP) and Lumpy Skin Disease (LSD) Live Vaccine.

Mycoplasma mycoides subsp. mycoides (Mmm) is the causative agent of contagious bovine pleuropneumonia (CBPP). Lumpy skin disease (LSD) is a viral disease of cattle caused by lumpy skin disease virus (LSDV). LSD and CBPP are both transboundary diseases spreading in the same areas of Africa and Asia. A combination vaccine to control CBPP and LSD offers significant value to small-scale livestock keepers as a single administration. Access to a bivalent vaccine may improve vaccination rates for both pathogens. In the present study, we evaluated the LSDV/CBPP live combined vaccine by testing the generation of virus neutralizing antibodies, immunogenicity, and safety on target species. In-vitro assessment of the Mycoplasma effect on LSDV growth in cell culture was evaluated by infectious virus titration and qPCR during 3 serial passages, whereas in-vivo interference was assessed through the antibody response to vaccination. This combined Mmm/LSDV vaccine could be used to protect cattle against both diseases with a single vaccination in the endemic countries. There were no adverse reactions detected in this study and inoculated cattle produced high levels of specific antibodies starting from day 7 post-vaccination, suggesting that this combination vaccine is both safe and effective.

Baseline analysis of Mycoplasma mycoides subsp. mycoides antigens as targets for a DIVA assay for use with a subunit vaccine for contagious bovine pleuropneumonia.

BACKGROUND: Mycoplasma mycoides subsp. mycoides (Mmm) is the causative agent of contagious bovine pleuropneumonia in cattle. A prototype subunit vaccine is being developed, however, there is currently no diagnostic test that can differentiate between infected cattle and those vaccinated with the prototype subunit vaccine. This study characterized Mmm proteins to identify potential antigens for use in differentiating infected from vaccinated animals. RESULTS: Ten Mmm antigens expressed as recombinant proteins were tested in an indirect ELISA using experimental sera from control groups, infected, and vaccinated animals. Data were imported into R software for analysis and drawing of the box and scatter plots while Cohen's Kappa assessed the level of agreement between the Mmm antigens. Two vaccine antigens (MSC_0499 and MSC_0776) were superior in detecting antibodies in sera of animals vaccinated with the subunit vaccines while two non-vaccine antigens (MSC_0636 and LppB) detected antibodies in sera of infected animals showing all clinical stages of the disease. Sensitivity and specificity of above 87.5% were achieved when the MSC_0499 and MSC_0636 antigens were tested on sera from vaccinated and infected animals. CONCLUSIONS: The MSC_0499 and MSC_0776 antigens were the most promising for detecting vaccinated animals, while MSC_0636 and LppB were the best targets to identify infected animals. Further testing of sera from vaccinated and infected animals collected at different time intervals in the field should help establish how useful a diagnostic test based on a cocktail of these proteins would be.

Evaluation of new generation macrolides for the treatment and metaphylaxis of contagious bovine pleuropneumonia (CBPP) in cattle experimentally infected with Mycoplasma mycoides subspecies mycoides.

BACKGROUND: Contagious bovine pleuropneumonia (CBPP) caused by Mycoplasma mycoides subspecies mycoides (Mmm) is an important disease of cattle that causes serious economic losses. With the known effectiveness of new generation macrolides, tulathromycin and gamithromycin were assessed in comparison with oxytetracycline as a positive control and saline as a negative control for effectiveness in inhibiting lung lesion development, promoting resolution, preventing spread and bacteriological clearance in susceptible local cattle breeds in two separate studies in Kenya and Zambia. Animals were monitored for clinical signs, sero-conversion as well as detailed post-mortem examination for CBPP lesions. RESULTS: Using the Hudson and Turner score for lesion type and size, tulathromycin protected 90%, gamithromycin 80%, and oxytetracycline 88% of treated animals in Kenya. In Zambia, all animals (100%) treated with macrolides were free of lung lesions, while oxytetracycline protected 77.5%. Using the mean adapted Hudson and Turner score, which includes clinical signs, post-mortem findings and serology, tulathromycin protected 82%, gamithromycin 56% and oxytetracycline 80% of the animals in Kenya whereas in Zambia, tulathromycin protected 98%, gamithromycin 94% and oxytetracycline 80%. The saline-treated groups had 93 and 92% lesions in Kenya and Zambia respectively, with Mmm recovered from 5/14 in Kenya and 10/13 animals in Zambia. Whereas the groups treated with macrolides were free from lesions in Zambia, in Kenya 5/15 tulathromycin-treated animals and 6/15 gamithromycin-treated animals showed lesions. Oxytetracycline-treated animals showed similarities with 3/14 and 4/15 showing lesions in Zambia and Kenya respectively and Mmm recovery from one animal in Kenya and six in Zambia. In both studies, lesion scores of saline-treated groups were significantly higher than those of the antibiotic treated groups (p < 0.001). In sentinel animals, CBPP lesions were detected and Mmm recovered from one and two animals mixed with the saline-treated groups in Kenya and Zambia respectively. CONCLUSIONS: This study demonstrated that tulathromycin, a mycoplasmacidal, can achieve metaphylactic protection of up to 80%, while non-recovery of Mmm from sentinels suggests macrolides effectiveness in preventing spread of Mmm. It is recommended that further studies are conducted to evaluate strategies comparing vaccination alone or combining vaccination and antibiotics to control or eradicate CBPP.

Information sharing and willingness-to-pay for CBPP vaccine in rural Kenya.

The study estimates cattle owners' willingness-to-pay (WTP) for Contagious Bovine Pleuropneumonia (CBPP) vaccine in Samburu county, Kenya. Of particular policy relevance, the study presents findings on WTP for i) improved access to vaccines and ii) timely access to disease-risk information. The mean price for a CBPP vaccine was estimated at KES 66 (USD 0.64). This price relates to a CBPP vaccine that requires a 1.8 h commute, cattle owners' receipt of timely information that the CBPP disease risk is low-moderate and the vaccine lowers the risk of either tail-drop or post-vaccine abortion. The conditional WTP for mean travel duration and high-risk information are similar at KES 53.9 and KES 51.5. The marginal effect on demand for a 1 h additional travel duration and provision of CBPP disease risk information was estimated as a 1.5 per cent reduction and 2.3 increase. The results of this study indicate that cattle owners value greater levels of knowledge concerning the changing risk profile of CBPP in their community and improved access to CBPP vaccination services. Enhanced engagement with cattle owners concerning CBPP would likely result in a greater utilisation of available CBPP vaccines, conditional on the perceived CBPP disease risk.

Epidemiological investigations of contagious caprine pleuropneumonia in selected districts of Borana zone, Southern Oromia, Ethiopia.

From November 2016 to April 2017, a cross-sectional study to determine the sero-prevalence of contagious caprine pleuropneumonia (CCPP) and to investigate its epidemiology was conducted in selected districts of Borana zone in Ethiopia. In addition, the study aimed at identifying Mccp antigens using species specific primer of PCR. A multistage random sampling was implemented to select districts, pastoral associations (villages), and households. A total of 890 serum samples of small ruminants that had not been vaccinated (goats n = 789 and sheep n = 101) were collected and screened for the presence of antibodies against Mycoplasma capricolum subspecies capripneumoniae using a competitive enzyme-linked immunosorbent assay. Lung tissues and pleural fluid samples were collected from 3 sero-positive and clinically suspected goats for isolation of Mycoplasma capricolum subspecies capripneumoniae. Serology showed that overall 31.2% (246/789) of goats and 12.9% (13/101) of sheep were positive with statistically significant differences between districts (p = 0.001). Multivariable logistic regression analysis revealed that goats from Moyale and Yabello districts had higher odds of being positive than goats from Elwoya district with odd ratios of 2.05 and 1.61, respectively. Age of goats was also significantly associated with sero-positivity (OR = 1.47; CI 95% 1.2-1.8). Mycoplasma capricolum subspecies capripneumoniae was identified in 6 (75%) of the tissue samples using species-specific primer of PCR. Besides improving the understanding of the epidemiology of CCPP in the selected districts and demonstrating its wide distribution, the study highly also provides evidence of the possible role of sheep in the maintenance of the disease.

Improving Quality Control of Contagious Caprine Pleuropneumonia Vaccine with Tandem Mass Spectrometry.

Vaccines to protect livestock against contagious caprine pleuropneumonia (CCPP) consist of inactivated, adjuvanted antigens. Quality control of these vaccines is challenging as total protein quantification provides no indication of protein identity or purity, and culture is not an option. Here, a tandem mass spectrometry approach is used to identify the mycoplasma antigen contained in reference samples and in commercial CCPP vaccines. By the same approach, the relative amounts of mycoplasma antigen and residual proteins originating from the production medium are determined. Mass spectrometry allows easy and rapid identification of the peptides present in the vaccine samples. Alongside the most probable mycoplasma species effectively present in the vaccines, a very high proportion of peptides from medium constituents are detected in the commercial vaccines tested.

Perceptions, circumstances and motivators affecting the implementation of contagious bovine pleuropneumonia control programmes in Nigerian Fulani pastoral herds.

Contagious bovine pleuropneumonia (CBPP) is an infectious disease of cattle which substantially contributes to poor productivity of the sub-Saharan pastoral livestock sector. In Nigeria and most of the West African countries, limited public funding for CBPP control have necessitated farmers to bear a bigger burden of managing the disease. Understanding the factors influencing decision of farmers to implement disease control programmes is therefore a key element in informing future policies aimed at improving CBPP management. This study explored perceptions of Nigerian Fulani pastoral herdsmen on the responsibility for cattle healthcare, and identified their circumstances and motivations in implementing CBPP management programmes. Field data were collected from 191 pastoral farmers using a semi-structured, interviewer-administered questionnaire. The results indicated that younger farmers were more likely than their older counterpart to accept the responsibility for CBPP management (p<0.01). This may signal future prospects for improved CBPP management where upcoming farmers could be encouraged to implement CBPP control programmes and uphold the costs. 13.6% of the farmers had no intention of implementing any CBPP control programme on farm, while 81.2% either had a positive intention or implemented at least one programme aimed at controlling CBPP. Intention to implement CBPP control programmes was significantly associated with educational attainment of farmers (p<0.01) and their access to CBPP control services offered by trained veterinarians (p<0.01). Farmers with negative attitudes towards implementing CBPP control programmes could be motivated to change their perspectives by advice from trusted sources and improved access to veterinary services. Conversely, farmers with positive attitudes towards implementing CBPP control programmes were more likely to be motivated by affordable veterinary services and advocacy on specific CBPP control programmes. As such, the former group of farmers will be more likely to benefit from programmes which focus on providing credible information from trusted sources, such as extension agents, veterinarians or successful peers. On the contrary, interventions targeting the latter group of farmers should prioritize cost-effective delivery of improved CBPP control technologies.

Policy analysis for delivery of contagious bovine pleuropneumonia control strategies in sub-Saharan Africa.

This paper presents a policy analysis for the implementation of contagious bovine pleuropneumonia (CBPP) control strategies in pastoral regions of sub-Saharan Africa, where the disease is endemic. A framework for policy analysis was adapted for this review. The framework has eight principal steps: defining the context of the policy, identifying the problem to be addressed by the policy, searching for evidence of the problem, identifying policy options, projecting policy outcomes, evaluating the potential policy options, weighing their outcomes and making the policy decision. The data and information used to search for evidence of the problem, options for solving the problem, and the projected outcomes of those options were obtained from both published and grey sources of literature. The policy problem for CBPP control in sub-Saharan Africa was identified as a failure to deliver control services to farmers whose cattle are at high risk of exposure to infection. The authors suggest the adoption of signed contractual agreements between the public and private sectors to support the vaccination of susceptible herds raised in endemic regions. Implementation of this policy will increase vaccination coverage of susceptible cattle herds since current vaccination coverage is low.

Les auteurs présentent une analyse des politiques afin de décider des stratégies de lutte à mener contre la péripneumonie contagieuse bovine (PPCB) dans les régions d'élevage pastoral d'Afrique subsaharienne, où la maladie sévit à l'état endémique. Un cadre d'analyse des politiques a été configuré pour les besoins de cette étude. Ce cadre comporte huit étapes principales : définition du contexte des politiques à mener ; identification du problème ; recherche d'éléments factuels relatifs au problème ; identification des mesures envisageables ; définition des résultats attendus ; évaluation des options potentielles ; comparaison des résultats ; prise de décision. Les données et les informations réunies lors de la recherche d'éléments factuels, les solutions proposées pour résoudre le problème et les résultats attendus de chaque option provenaient de sources publiées ainsi que de la littérature grise. Il ressort de cette analyse que le principal problème en matière de lutte contre la PPCB en Afrique subsaharienne est l'absence de prestations de services appropriées destinées aux éleveurs dont les bovins sont particulièrement exposés au risque d'infection. Les auteurs proposent de recourir à des accords contractuels engageant le secteur tant public que privé en soutien de la vaccination des troupeaux sensibles dans les régions endémiques. La mise en oeuvre de cette politique permettrait d'accroître la couverture vaccinale du cheptel bovin sensible, qui est actuellement d'un niveau médiocre.

Los autores presentan un análisis de las políticas de aplicación de estrategias de lucha contra la perineumonía contagiosa bovina en regiones de pastoreo del África subsahariana, donde la enfermedad es endémica. Para llevar a cabo el estudio se adaptó un modelo de análisis de políticas que consta de ocho pasos principales: definir el contexto de la política; acotar el problema al que la política debe dar respuesta; buscar datos empíricos que evidencien el problema; determinar diferentes opciones políticas; proyectar los resultados de cada política; evaluar las posibles opciones políticas; comparar sus resultados; y decidirse por una u otra política. Los datos y la información utilizados para buscar datos probatorios del problema, determinar posibles opciones para resolverlo y proyectar los resultados que vayan a deparar esas opciones procedían de fuentes bibliográficas publicadas y de documentación inédita. Se llegó a la conclusión de que el problema de las políticas de lucha contra la perineumonía contagiosa bovina en el África subsahariana reside en la ausencia de servicios zoosanitarios en beneficios de los ganaderos cuyos animales están muy expuestos al riesgo de infección. Los autores proponen que el sector público y el privado suscriban acuerdos contractuales para respaldar la vacunación de los rebaños susceptibles en las regiones de endemismo. La aplicación de esta política incrementará la cobertura de vacunación de los rebaños vacunos susceptibles, que en la actualidad es escasa.

Capsular polysaccharide from Mycoplasma mycoides subsp. mycoides shows potential for protection against contagious bovine pleuropneumonia.

Contagious Bovine Pleuropneumonia (CBPP) is a severe respiratory disease caused by Mycoplasma mycoides subsp. mycoides (Mmm) which is widespread in Africa. The capsule polysaccharide (CPS) of Mmm is one of the few identified virulence determinants. In a previous study, immunization of mice against CPS generated antibodies, but they were not able to prevent multiplication of Mmm in this model animal. However, mice cannot be considered as a suitable animal model, as Mmm does not induce pathology in this species. Our aim was to induce antibody responses to CPS in cattle, and challenge them when they had specific CPS antibody titres similar or higher than those from cattle vaccinated with the live vaccine. The CPS was linked to the carrier protein ovalbumin via a carbodiimide-mediated condensation with 1-ethyl-3(3-imethylaminopropyl) carbodiimide (EDC). Ten animals were immunized twice and challenged three weeks after the booster inoculation, and compared to a group of challenged non-immunized cattle. When administered subcutaneously to adult cattle, the vaccine elicited CPS-specific antibody responses with the same or a higher titre than animals vaccinated with the live vaccine. Pathology in the group of immunized animals was significantly reduced (57%) after challenge with Mmm strain Afadé compared to the non-immunized group, a figure in the range of the protection provided by the live vaccine.

A meta-analysis of contagious caprine pleuropneumonia (CCPP) in Ethiopia.

This systematic literature review was initiated due to lack of comprehensive information on the status and distribution of contagious caprine pleuropneumonia (CCPP) in Ethiopia. The objectives of the review were thus to provide a pooled prevalence estimate of CCPP in the country and asses the level of in between study variance among the available reports. Manual and electronic search was conducted between 8th of January and 25th of June 2015. A total of twelve published articles and one MSc thesis was retrieved from 19 initially identified studies. Twenty five animal level datasets were extracted at regional level considering some hypothesized predictors. The retrieved data were summarized in a meta-analytical approach. Accordingly, the pooled prevalence estimate of CCPP was 25.7% (95% CI:20.9,31.0). The inverse variance square (I(2)) that explains the variation in effect size attributed to reports true heterogeneity was 95.7%.The sub-group analysis was also computed for assumed predictors including, age, sex, type of study population, production systems and regional states. Among these predictors, study population type revealed statistically significant difference (P<0.05). Accordingly, the prevalence estimate for samples collected at abattoir was 39.2%, while that of samples collected at field level was 22.4%. In the final model, type of study population fitted the multivariable meta-regression model accounting for 22.87% of the explainable proportion of heterogeneity among the presumed predictors. Evidence on isolation and confirmation of Mycoplasma capricolum subspp. capripneumonie in the country was obtained from five regional states. In conclusion, it is recommended to further investigate facilities related with transportation and collection premises along with potential role of sheep in the epidemiology of CCPP. Finally, the review emphasizes the need for monitoring the ongoing CCPP control intervention and introduces amendments based on the findings. Besides more surveys are needed in some of the regions where no or few valid data was available.

Recombinant Mycoplasma mycoides proteins elicit protective immune responses against contagious bovine pleuropneumonia.

Mycoplasma mycoides subsp. mycoides (Mmm) is the causative agent of contagious bovine pleuropneumonia (CBPP), a devastating respiratory disease mainly affecting cattle in sub-Saharan Africa. The current vaccines are based on live-attenuated Mmm strains and present problems with temperature stability, duration of immunity and adverse reactions, thus new vaccines are needed to overcome these issues. We used a reverse vaccinology approach to identify 66 Mmm potential vaccine candidates. The selection and grouping of the antigens was based on the presence of specific antibodies in sera from CBPP-positive animals. The antigens were used to immunize male Boran cattle (Bos indicus) followed by a challenge with the Mmm strain Afadé. Two of the groups immunized with five proteins each showed protection after the Mmm challenge (Groups A and C; P<0.05) and in one group (Group C) Mmm could not be cultured from lung specimens. A third group (Group N) showed a reduced number of animals with lesions and the cultures for Mmm were also negative. While immunization with some of the antigens conferred protection, others may have increased immune-related pathology. This is the first report that Mmm recombinant proteins have been successfully used to formulate a prototype vaccine and these results pave the way for the development of a novel commercial vaccine.

Experimental evaluation of inactivated and live attenuated vaccines against Mycoplasma mycoides subsp. mycoides.

The current control method for contagious bovine pleuropneumonia (CBPP) in Africa is vaccination with a live, attenuated strain of Mycoplasma mycoides subsp. mycoides (Mmm). However, this method is not very efficient and often causes serious adverse reactions. Several studies have attempted to induce protection using inactivated mycoplasma, but with widely contradictory results. Therefore, we compared the protective capacity of the live T1/44 vaccine with two inactivated preparations of Mmm strain Afadé, inoculated with an adjuvant. Protection was measured after a challenge with Afadé. The protection levels were 31%, 80.8% and 74.1% for the formalin-inactivated, heat-inactivated and live attenuated preparations, respectively. These findings indicate that low doses of heat-inactivated Mmm can offer protection to a level similar to the current live attenuated (T1/44) vaccine formulation.

Analysis of immune responses to recombinant proteins from strains of Mycoplasma mycoides subsp. mycoides, the causative agent of contagious bovine pleuropneumonia.

Current contagious bovine pleuropneumonia (CBPP) vaccines are based on live-attenuated strains of Mycoplasma mycoides subsp. mycoides (Mmm). These vaccines have shortcomings in terms of efficacy, duration of immunity and in some cases show severe side effects at the inoculation site; hence the need to develop new vaccines to combat the disease. Reverse vaccinology approaches were used and identified 66 candidate Mycoplasma proteins using available Mmm genome data. These proteins were ranked by their ability to be recognized by serum from CBPP-positive cattle and thereafter used to inoculate naïve cattle. We report here the inoculation of cattle with recombinant proteins and the subsequent humoral and T-cell-mediated immune responses to these proteins and conclude that a subset of these proteins are candidate molecules for recombinant protein-based subunit vaccines for CBPP control.

Serological prevalence of contagious bovine pleuropneumonia in agro-pastoral areas of Nigeria.

BACKGROUND: Contagious bovine pleuropneumonia (CBPP), an infection of cattle caused by the small colony biotype of Mycoplasma mycoides subspecies mycoides (MmmSC), is a significant constraint to improved pastoral cattle productivity in sub-Saharan Africa. This cross-sectional study was aimed to estimate serological prevalence of CBPP and identify risk factors for herd sero-positivity within agro-pastoral areas of Nigeria. RESULTS: The herd level prevalence of CBPP was 54.7% (95% confidence interval (CI) = 47.7-62.0), and proportion of animals with detectable MmmSC monoclonal antibody was 30.2% (95% CI = 26.3-34.4). Herds were more likely to be sero-positive if they were potentially exposed to recent CBPP outbreaks (odds ratio (OR) = 4.9, 95% CI = 2.4-10.1) or of larger sizes (OR = 3.0, 95% CI = 1.2-7.5). Herds vaccinated against the disease had lower odds of being sero-positive (OR = 0.12, 95% CI = 0.02-0.6) than unvaccinated herds. CONCLUSIONS: CBPP is endemic to agro-pastoral areas, and it is doubtful if the current control strategies are making real impact in reducing production losses. Although eradication is more likely to be achieved through regional approaches, enhanced vaccination coverage supported with targeted surveillance and a trace back system based on cattle trade and movement records will sustain effective control of the disease in the Nigerian cattle population.

Mathematical modelling of the transmission dynamics of contagious bovine pleuropneumonia reveals minimal target profiles for improved vaccines and diagnostic assays.

Contagious bovine pleuropneumonia (CBPP) is a cattle disease that has hampered the development of the livestock sector in sub-Saharan Africa. Currently, vaccination with a live vaccine strain is its recommended control measure although unofficial antimicrobial use is widely practiced. Here, modelling techniques are used to assess the potential impact of early elimination of infected cattle via accurate diagnosis on CBPP dynamics. A herd-level stochastic epidemiological model explicitly incorporating test sensitivity and specificity is developed. Interventions by annual vaccination, annual testing and elimination and a combination of both are implemented in a stepwise manner and their effectiveness compared by running 1000 simulations per intervention over ten years. The model predicts that among the simulated interventions, the ones likely to eliminate the disease from an isolated herd all involved annual vaccination of more than 75% of the animals with a vaccine that protects for at least 18 months combined with annual testing (and elimination of positive reactors) of 75% of the animals every six months after vaccination. The highest probability of disease elimination was 97.5% and this could occur within a median of 2.3 years. Generally, our model predicts that regular testing and elimination of positive reactors using improved tests will play a significant role in minimizing CBPP burden especially in the current situation where improved vaccines are yet to be developed.

An adenoviral vector expressing lipoprotein A, a major antigen of Mycoplasma mycoides subspecies mycoides, elicits robust immune responses in mice.

Contagious bovine pleuropneumonia (CBPP), caused by Mycoplasma mycoides subsp. mycoides small colony type (MmmSC), is a devastating respiratory disease of cattle. In sub-Saharan Africa, where CBPP is enzootic, live attenuated vaccines are deployed but afford only short-lived protection. In cattle, recovery from experimental MmmSC infection has been associated with the presence of CD4(+) T lymphocytes that secrete interferon gamma in response to MmmSC, and in particular to the lipoprotein A (LppA) antigen. In an effort to develop a better vaccine against CBPP, a viral vector (Ad5-LppA) that expressed LppA was generated from human adenovirus type 5. The LppA-specific immune responses elicited by the Ad5-LppA vector were evaluated in mice, and compared to those elicited by recombinant LppA formulated with a potent adjuvant. Notably, a single administration of Ad5-LppA, but not recombinant protein, sufficed to elicit a robust LppA-specific humoral response. After a booster administration, both vector and recombinant protein elicited strong LppA-specific humoral and cell-mediated responses. Ex vivo stimulation of splenocytes induced extensive proliferation of CD4(+) T cells for mice immunized with vector or protein, and secretion of T helper 1-associated and proinflammatory cytokines for mice immunized with Ad5-LppA. Our study - by demonstrating the potential of a viral-vectored prototypic vaccine to elicit prompt and robust immune responses against a major antigen of MmmSC - represents a first step in developing a recombinant vaccine against CBPP.