Vaccination of Cattle with the N Terminus of LppQ of Mycoplasma mycoides subsp. mycoides Results in Type III Immune Complex Disease upon Experimental Infection

Contagious bovine pleuropneumonia (CBPP) is a serious respiratory disease of cattle caused by Mycoplasma mycoides subsp. mycoides. Current vaccines against CBPP induce short-lived immunity and can cause severe postvaccine reactions. Previous studies have identified the N terminus of the transmembrane lipoprotein Q (LppQ-N') of M. mycoides subsp. mycoides as the major antigen and a possible virulence factor. We therefore immunized cattle with purified recombinant LppQ-N' formulated in Freund's adjuvant and challenged them with M. mycoides subsp. mycoides. Vaccinated animals showed a strong seroconversion to LppQ, but they exhibited significantly enhanced postchallenge glomerulonephritis compared to the placebo group (P = 0.021). Glomerulonephritis was characterized by features that suggested the development of antigen-antibody immune complexes. Clinical signs and gross pathological scores did not significantly differ between vaccinated and placebo groups. These findings reveal for the first time the pathogenesis of enhanced disease as a result of antibodies against LppQ during challenge and also argue against inclusion of LppQ-N' in a future subunit vaccine for CBPP

Contagious Caprine Pleuropneumonia

Contagious caprine pleuropneumonia (CCPP), caused by Mycoplasma capricolum subsp. capripneumoniae, is an OIE-listed disease affecting goats and wild ungulate species. CCPP is present in Africa, the Middle East, and Central Asia, but its exact distribution is unknown, particularly in Asia. It is enzootic in the Middle East and East Africa, while it has only been sporadically reported in North and Central Africa and, though suspected, has never been identified in West Africa. In addition, there are very few studies reporting the prevalence and losses induced by CCPP, which are greatly underestimated. This uncertainty over the distribution and impact of CCPP is partly due to the fastidious nature of its etiologic agent, which is difficult to identify, particularly when it circulates in an insidious, mild, or asymptomatic form, favored by the use of antibiotic treatments. However, specific molecular and serological tests are now available for the diagnosis of CCPP, even in the absence of isolation. The main limitation of CCPP surveillance remains the lack of awareness by veterinary services. Vaccines based on inactivated antigens in saponin can induce good protection and their variable quality may now be assessed using a specific ELISA. However, they are very expensive, and there is a paucity of vaccine producers to satisfy their demand. Efforts must urgently be directed to the development of cheaper, quality-controlled vaccines to be extensively used in the field. The global campaign to eradicate “peste des petits ruminants” by 2030 may be a great opportunity to target other goat diseases such as CCPP