Abstract
Mycobacterium bovis is the causative agent of bovine tuberculosis (TB), a disease that affects approximately 5% of Argentinean cattle. Among the molecular methods for genotyping, the most convenient are spoligotyping and variable number of tandem repeats (VNTR). A total of 378 samples from bovines with visible lesions consistent with TB were collected at slaughterhouses in three provinces, yielding 265 M. bovis spoligotyped isolates, which were distributed into 35 spoligotypes. In addition, 197 isolates were also typed by the VNTR method and 54 combined VNTR types were detected. There were 24 clusters and 27 orphan types. When both typing methods were combined, 98 spoligotypes and VNTR types were observed with 27 clusters and 71 orphan types. By performing a meta-analysis with previous spoligotyping results, we identified regional and temporal trends in the population structure of M. bovis. For SB0140, the most predominant spoligotype in Argentina, the prevalence percentage remained high during different periods, varying from 25.5-57.8% (1994-2011). By contrast, the second and third most prevalent spoligotypes exhibited important fluctuations. This study shows that there has been an expansion in ancestral lineages as demonstrated by spoligotyping. However, exact tandem repeat typing suggests dynamic changes in the clonal population of this microorganism.
Highlights
Bovine tuberculosis (BTB) is an infectious disease primarily caused by Mycobacterium bovis, which affects a wide range of mammals, including humans (Amanfu 2006)
Desirable characteristics for a typing method are related to the stability of the strain and the diversity within the species (Skuce & Neill 2001). Spoligotyping may fulfil these characteristics in some cases, other typing methods such as variable number of tandem repeats (VNTR) must be performed to discriminate among isolates, especially in settings where one spoligotype is largely predominant or has been used to investigate a recent transmission
Santa Fe had the majority of new spoligotypes, most likely because of the active TB eradication program in that province
Summary
Bovine tuberculosis (BTB) is an infectious disease primarily caused by Mycobacterium bovis, which affects a wide range of mammals, including humans (Amanfu 2006). The methods for genotyping M. bovis and other MTBC species include restriction fragment length polymorphism (Otal et al 1991, Collins et al 1993) and VNTR (Haddad et al 2001). Desirable characteristics for a typing method are related to the stability of the strain and the diversity within the species (Skuce & Neill 2001). Spoligotyping may fulfil these characteristics in some cases, other typing methods such as VNTR must be performed to discriminate among isolates, especially in settings where one spoligotype is largely predominant or has been used to investigate a recent transmission. Previous studies have demonstrated a wide diversity of M. bovis spoligotypes for cattle populations in Latin American countries. The distribution of circulating M. bovis spoligotypes in five Latin American countries has been analysed recently (Zumárraga et al 2012). The aim of this work was to assess the genetic diversity of M. bovis in Argentina and to envisage temporal and spatial trends in the clonal population of this pathogen in the context of active transmissions in cattle
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call