38 . CIRAD 2008
Contagious bovine pleuropneumonia—
new diagnostic, molecular epidemiology and vaccination methods
Controlling contagious bovine pleuropneumonia, a serious cattle disease in Africa, is a major challenge for CIRAD. In recent years, knowledge on this disease and its causal mycoplasm has increased considerably with the sequencing of several of the pathogen’s genomes, the development of new detection tests, the unravelling of the protective immune systems and the development of vaccination strategies.
C
ontageous bovine pleuropneumonia (CBPP), caused by the Mycoplasma mycoides subsp. mycoides small colony (MmmSC) biotype, is a respiratory disease of cattle in Africa, where it has a serious socioeconomic impact. Sporadic outbreaks have also occurred in southern Europe, with the last case detected in Portugal in 1999. In Africa, this disease is hard to control—sanitary measures such as controlling cattle movements
Partners Laboratoire central vétérinaire de Bamako (LCV, Mali), Laboratoire national vétérinaire de Garoua (LANAVET, Cameroon), Onderstepoort Veterinary Institute (OVI, South Africa), Institut de la recherche agronomique (INRA, France), Ecole vétérinaire de Toulouse (France), Centre de bio-informatique bordelais (CBIB, France), Agence française de sécurité sanitaire des aliments (AFSSA, France), Genoscope (France)
and slaughtering infected animals are complicated to set up and implement and annual vaccination campaigns are expensive (moreover, the vaccines have limited efficacy). As reference CBPP laboratory for the World Organisation for Animal Health (OIE) and the Food and Agriculture Organization of the United Nations (FAO), CIRAD has been investigating ways to control this disease for several years. Recently, sequencing data on several genomes of MmmSC and other related strains paved the way to the development of new diagnostic, molecular epidemiology and vaccination approaches.
A more sensitive detection technique CIRAD has developed a real-time polymerase chain reaction (rtPCR) technique to improve conventional
PCR detection of the mycoplasm. With this technique, the detection sensitivity for field samples can range from 3 to 80 colony forming units, or from 4 to 80 femtogrammes (fg) of DNA (1 fg = 10−15 g). From a practical standpoint, this technique reduces the risk of contamination, enables mycoplasm quantification and improves quality assurance.
Determining the geographical origin of strains Epidemiological progress has also been achieved. Eight polymorphic loci were thus selected by comparing two complete genomes. An analysis of these multilocus sequences was applied to 51 strains of various origins. It revealed three geographical groups: the first is mainly from West and Central Africa, the second is present in South and East Africa, Australia and India, and the last is located in Europe. This study also proved