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

AbstractThe 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

Efficacy of two vaccine formulations against contagious bovine pleuropneumonia (CBPP) in Kenyan indigenous cattle

AbstractA live, attenuated vaccine is currently the only viable option to control of CBPP in Africa. It has been suggested that simple modifications to current vaccines and protocols might improve efficacy in the field. In this report we compared the current vaccine formulation with a buffered preparation that maintains Mycoplasma viability at ambient temperature for a longer time. Groups of animals were vaccinated with the two formulations and compared with non vaccinated groups. Half of the animals in each group were challenged 3months post vaccination, the other half after 16months. Protection levels were measured using the pathology index, calculated from post mortem scores of lesions from animals killed during the course of clinical disease. In the challenge at 3months post vaccination, the protection levels were 52% and 77% for the modified and current vaccine preparations, respectively. At 16months post vaccination, the protection levels were 56% and 62% for the modified and current vaccine preparations, respectively. These findings indicate that there are no differences in protection levels between the two vaccines. Because of its longer half life after reconstitution, the modified vaccine might be preferred in field situations where the reconstituted vaccine is likely not to be administered immediately

Manifestation of contagious bovine pleuropneumonia in seven month-old calves infected via bronchoscope and in contact transmission

Mycoplasma mycoides subsp. mycoides (Mmm) causes contagious  bovine pleuropneumonia (CBPP) in adult cattle however calves younger than 6 months develop mostly arthritis and associated lameness, but very few lesions in the lungs, suggesting that Mycoplasma does not easily colonize lungs of young calves. The aim of this study was to assess effects of CBPP in 7-month-old calves following infection by in-contact transmission; and manifestation in adult cattle and calves infected via intubation method. Both adult and seven month old calves developed respiratory indications of CBPP. Although none of the adult cattle developed arthritis, 7/10 and all 5 calves infected by intubation and in-contact transmission methods respectively developed arthritis. The results show that 7-month-old calves, whether infected by intubation or in-contact method develop respiratory signs similar to adult cattle as well as arthritis as seen in calves younger than six months. This suggests that at seven months, calves have developed susceptibility to lung lesions but still have a propensity for damage in the joints like very young calves.Key words: Contagious bovine pleuropneumonia, Mycoplasma mycoides subsp. mycoides, Calves, intubation, in-contact transmission Manifestation de la pleuropneumonie contagieuse bovine chez des veaux de sept mois infectes avec un bronchoscope et par contactMycoplasma mycoides sous-espèce mycoides (Mmm) est responsable de la pleuropneumonie contagieuse bovine (PPCB) chez les bovins adultes, mais les veaux de moins de 6 mois développent essentiellement de l’arthrite et de la boiterie associée, mais très peu de lésions pulmonaires, ce qui porte à croire que Mycoplasma ne colonise pas facilement les poumons des jeunes veaux. Le but de cette étude était d’évaluer les effets de la PPCB chez les veaux de 7 mois infectés par contact, et les manifestations chez les bovins adultes et les veaux infectés par intubation. Les veaux adultes et ceux de sept mois ont développé des signes respiratoires de PPCB. Bien qu’aucun des bovins adultes n’ait développé de l’arthrite, 7/10 et tous les 5 veaux infectés par intubation et transmission par contact ont respectivement développé de l’arthrite. Les résultats montrent que les veaux de 7 mois, qu’ils soient infectés par intubation ou par contact, développent des signes respiratoires similaires à ceux des bovins adultes, tels que l’arthrite chez les veaux de moins de six mois. Ceci donne à penser qu’à sept mois les veaux ont développé une susceptibilité aux lésions pulmonaires, mais ont toujours une propension d’endommagement des  articulations comme les très jeunes veaux.Mots-clés : pleuropneumonie contagieuse bovine, Mycoplasma mycoides sous-espèce mycoides, veaux, intubation, transmission par contact

An international collaborative study to determine the prevalence of contagious caprine pleuropneumonia by monoclonal antibody-based cELISA

Background: Few serological tests are available for detecting antibodies against Mycoplasma capricolum subsp. capripneumoniae, the causal agent of contagious caprine pleuropneumonia (CCPP). The complement fixation test, the test prescribed for international trade purposes, uses a crude antigen that cross-reacts with all the other mycoplasma species of the "mycoides cluster" frequently infecting goat herds. The lack of a more specific test has been a real obstacle to the evaluation of the prevalence and economic impact of CCPP worldwide. A new competitive ELISA kit for CCPP, based on a previous blocking ELISA, was formatted at CIRAD and used to evaluate the prevalence of CCPP in some regions of Kenya, Ethiopia, Mauritius, Tajikistan and Pakistan in an international collaborative study. Results: The strict specificity of the test was confirmed in CCPP-free goat herds exposed to other mycoplasma species of the ''mycoides cluster". Prevalence studies were performed across the enzootic range of the disease in Africa and Asia. Seroprevalence was estimated at 14.6% in the Afar region of Ethiopia, whereas all the herds presented for CCPP vaccination in Kenya tested positive (individual seroprevalence varied from 6 to 90% within each herd). In Mauritius, where CCPP emerged in 2009, nine of 62 herds tested positive. In Central Asia, where the disease was confirmed only recently, no positive animals were detected in the Wakhan District of Afghanistan or across the border in neighboring areas of Tajikistan, whereas seroprevalence varied between 2.7% and 44.2% in the other districts investigated and in northern Pakistan. The test was also used to monitor seroconversion in vaccinated animals. Conclusions: This newly formatted CCPP cELISA kit has retained the high specificity of the original kit. It can therefore be used to evaluate the prevalence of CCPP in countries or regions without vaccination programs. It could also be used to monitor the efficacy of vaccination campaigns as high-quality vaccines induce high rates of seroconversion. (Résumé d'auteur