Mycobacterium bovis ESAT-6, CFP-10 and EspC antigens show high conservation among field isolates.

ESAT-6, CFP-10 and EspC are virulence factors that have been extensively assayed for bovine and human tuberculosis diagnosis due their potent T-cell inducing activities. While polymorphisms of ESAT-6 and CFP-10 were analyzed, with the description of CFP-10 variants in M. tuberculosis, this fact has not been explored in M. bovis field isolates. The coding sequences of esxA (ESAT-6), esxB (CFP-10) and mb3645c (EspC) from 58 M. bovis strains exhibiting genomic variability (spoligotyping) were analyzed. Two genes -esxA and esxB - remained invariant while mb3645c exhibited one synonymous polymorphism (G to A mutation, position 66bp) in one isolate, compared to M. bovis AF2122/97 reference strain. All isolates exhibited a synonymous nucleotide polymorphism simultaneously (G to A mutation, position 255bp), compared to M. tuberculosis H37Rv reference strain. This study confirms the high conservation for ESAT-6, CFP-10 and EspC in local M. bovis field isolates and reinforce the use of these three antigens in the diagnosis of bovine tuberculosis. Further studies should be performed to globally confirm these findings.

Bovine tuberculosis in domestic pigs: Genotyping and distribution of isolates in Argentina.

Bovine tuberculosis is caused by Mycobacterium bovis and affects primarily cattle, among many other mammal species. In this study, 250 isolates of M. bovis collected from pigs slaughtered in Argentina were typed by spoligotyping. Over half of the isolates (66%) grouped into two spoligotypes. Moreover, SB0140 was the most frequent spoligotype detected in the three performed samplings. In addition, 195 isolates were typed through variable number of tandem repeats (VNTR) by selecting 7 loci (MIRU 16­26­ 31 and ETR A­B­C­D). The relationship among the patterns was performed using a goeBURST algorithm and the main clonal complexes grouped 110 isolates (56%). Although pigs shared genotypes with cattle (n = 21), some patterns were detected only in pigs (n=14). These findings suggest the pig as a source ofM. bovis infection to cattle.

Tuberculosis in swine co-infected with Mycobacterium avium subsp. hominissuis and Mycobacterium bovis in a cluster from Argentina.

SUMMARY In Argentina little is known about the epidemiology of tuberculosis (TB) infection in swine. We characterized the epidemiological dynamics of Mycobacterium avium complex (MAC) infection in a swine population of Argentina using molecular tools and spatial analysis techniques. Isolates (n = 196) obtained from TB-like lesions (n = 200) were characterized by polymerase chain reaction. The isolates were positive to either M. bovis (IS6110) (n = 160) or M. avium (IS1245) (n = 16) while the remaining 20 (10.2%) isolates were positive to both M. bovis and M. avium. The detection of both bacteria together suggests co-infection at the animal level. In addition, MAC-positive isolates (n = 36) were classified as M. avium subsp. avium (MAA) (n = 30) and M. avium subsp. hominissuis (MAH) (n = 6), which resulted in five genotypes when they were typed using mycobacterial interspersed repetitive unit, variable number of tandem repeats (MIRU-VNTR). One significant (P = 0.017) spatial clustering of genotypes was detected, in which the proportion of MAH isolates was larger than expected under the null hypothesis of even distribution of genotypes. These results show that in Argentina the proportion of TB cases in pigs caused by M. avium is larger than that reported in earlier studies. The proportion of M. bovis-MAC co-infections was also higher than in previous reports. These results provide valuable information on the epidemiology of MAC infection in swine in Argentina.

Understanding the relationship between Mycobacterium bovis spoligotypes from cattle in Latin American countries.

Spoligotyping is the most frequently used method for genotyping isolates of Mycobacterium bovis worldwide. In the current work, we compared spoligotypes from 1684 M. bovis isolates from Argentina (816), Brazil (412), Chile (66), Mexico (274) and Venezuela (116), obtained from cattle, humans, pigs, wild boars, farmed deer, goats, buffaloes, cats, and wild animals. A total of 269 different spoligotypes were found: 142 (8.4%) isolates presented orphan spoligotypes, whereas 1542 (91.6%) formed 113 different clusters. In cattle, SB0140 was the most representative spoligotype with 355 (24.6%) isolates, followed by SB0121 with 149 (10.3%) isolates. Clustering of spoligotypes ranged from 95.2% in Argentina to 85.3% in Mexico. Orphan spoligotypes were also variable, ranging from 23.7% in Mexico to 4.1% in Brazil. A large proportion of spoligotypes were common to the neighboring countries Argentina, Brazil and Chile. In conclusion, despite the diversity of spoligotypes found in the five countries studied, there are major patterns that predominate in these neighboring countries. These clusters may reflect a long-lasting active transmission of bovine tuberculosis or common historical origins of infection.