Poster presented in 33rd Annual Congress of the European Society of Mycobacteriology

July 1^st, 2012

Alvarez J., de Juan L., Bezos J., Casal C., Cuartero C., Garcia I., Gimeno J., Aranaz A., Mateos A., Dominguez L. and Gomez-Mampaso E.

M. avium complex (MAC) is formed by several species/subspecies that show a surprising phenotypic and genotypic variability, including from strict pathogens associated with disease to widely distributed saprophytic microorganism. Among the first ones M. avium subsp. avium (Maa), causative agent of avian tuberculosis, is an important bacteria in the veterinary field due to its pathogenicity in birds and its potential effect as inductor of cross-reacting responses in routine tuberculosis diagnostic tests in cattle. Although primarily found in birds, Maa has been also isolated from a wide range of mammal species including humans, sometimes associated with disease. However, Maa shows a very high degree of genetic homogeneity between strains, making difficult the identification of signatures potentially related to virulence that could help to determine the clinical significance of its isolation. The objective of this study was to analyze through PCR and sequencing several molecular targets in Maa strains cultured from animals with and without clinical symptoms to determine if their genetic differences could be associated with clinical presentation and/or host species in the DNA. A total of 171 Maa strains were recovered and identified from tissue samples collected from birds (n=27) and mammals [n=144, including livestock (cattle, goats, swine) and wildlife (wild boar, red deer]. Presence of insertion sequences IS901 and IS1245 was determined in all of them, and a subset of 81 of the strains selected randomly to include different host species, and isolates from individuals with and without lesions was subjected to the PCR amplification and sequencing of the hsp65 and rpoβ genes and the internal transcribed spacer. All analyzed strains had the expected pattern regarding presence of insertion sequences (IS901+/ IS1245+). In the subset of isolates analyzed through sequencing, no single nucleotide polymorphisms (SNPs) were identified in the hsp65 gene, and limited variability was found in the rpoβ, that could not be associated to the presence of lesions. Our findings thus confirm the homogeneity of isolates belonging to Maa, and highlight the importance of the host/host-pathogen interaction in the triggering of disease in an infected host

	Servicio de Micobacterias (MYC). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM).
	Departamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM).