African 1, an Epidemiologically Important Clonal Complex of Mycobacterium bovis Dominant in Mali, Nigeria, Cameroon, and Chad

Abstract

We have identified a clonal complex of Mycobacterium bovis present at high frequency in cattle in population samples from several sub-Saharan west-central African countries. This closely related group of bacteria is defined by a specific chromosomal deletion (RDAf1) and can be identified by the absence of spacer 30 in the standard spoligotype typing scheme. We have named this group of strains the African 1 (Af1) clonal complex and have defined the spoligotype signature of this clonal complex as being the same as the M. bovis BCG vaccine strain but with the deletion of spacer 30. Strains of the Af1 clonal complex were found at high frequency in population samples of M. bovis from cattle in Mali, Cameroon, Nigeria, and Chad, and using a combination of variable-number tandem repeat typing and spoligotyping, we show that the population of M. bovis in each of these countries is distinct, suggesting that the recent mixing of strains between countries is not common in this area of Africa. Strains with the Af1-specific deletion (RDAf1) were not identified in M. bovis isolates from Algeria, Burundi, Ethiopia, Madagascar, Mozambique, South Africa, Tanzania, and Uganda. Furthermore, the spoligotype signature of the Af1 clonal complex has not been identified in population samples of bovine tuberculosis from Europe, Iran, and South America. These observations suggest that the Af1 clonal complex is geographically localized, albeit to several African countries, and we suggest that the dominance of the clonal complex in this region is the result of an original introduction into cows naïve to bovine tuberculosis.

Molecular epidemiology of human and animal tuberculosis in Ibadan, Southwestern Nigeria

“…In Mali, a strain with a similar spoligopattern to SB0944, reported previously in Nigeria, Chad and Cameroon was also observed in 13 of the 20 strains studied (Muller et al, 2008). This therefore gives strong indications regarding clonal distribution of M. bovis strains in West Africa (Muller et al, 2009), and further emphasizes the relevance of molecular techniques in the epidemiology of tuberculosis.…”

“…A similar spoligotype lacking spacer 30 was also reported from a human with pulmonary BTB in Ghana (Meyer et al, 2008). These spoligotypes are members of the African 1 (Af1) clonal complex characterized by the absence of spacer 30 (Muller et al, 2009). Furthermore, the SB0944 spoligotype which is common in West Africa was reported to be the most prevalent strain in cattle in Nigeria, Chad and Cameroon (Muller et al, 2009).…”

“…These spoligotypes are members of the African 1 (Af1) clonal complex characterized by the absence of spacer 30 (Muller et al, 2009). Furthermore, the SB0944 spoligotype which is common in West Africa was reported to be the most prevalent strain in cattle in Nigeria, Chad and Cameroon (Muller et al, 2009). Our findings, based on the spoligotyping data, are thus consistent with the findings in this recently published study (Muller et al, 2009).…”

“…Furthermore, the SB0944 spoligotype which is common in West Africa was reported to be the most prevalent strain in cattle in Nigeria, Chad and Cameroon (Muller et al, 2009). Our findings, based on the spoligotyping data, are thus consistent with the findings in this recently published study (Muller et al, 2009). The human isolate (hb74) with the SB0944 spoligotype presented with an ETR A-E genotype of 54543 which had also been reported in two of 59 SB0944 strains previously isolated in Nigeria (Muller et al, 2009).…”

“…It has been used in developed countries for M. bovis transmission studies and has produced highly informative data when combined with traditional epidemiology . It has also been used in a number of African countries where it revealed very interesting information regarding the clonal expansion of M. bovis in West Africa (Muller et al, 2009). Using this technique in Africa will help in elucidating the extent of spread of MTC and addressing speculations regarding risk factors.…”