The incidence of diseases caused by nontuberculous mycobacteria (NTM) is increasing annually worldwide, including Japan. Mycobacterium avium subsp. hoiminissuis (MAH) is one of the most common NTM species responsible for chronic lung diseases in animals and humans. In the current study, mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing was employed to characterize the genetic diversity of swine MAH isolates from Kyushu, Japan. In total, 309 isolates

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... obtained from the lymph nodes of 107 pigs not displaying any clinical signs of disease, of which 307 were identified as MAH, comprising 173 strains. Based on eight established MIRU-VNTR loci, the MAH strains represented 50 genotypes constituting three lineages, and 29 had not been described in the Mac French National Institute for Agricultural Research Nouzilly MIRU-VNTR (Mac-INMV) database. MAH was the dominant M. avium complex (MAC) in pigs from Kyushu, and there was high genetic diversity among genotype profiles of MAH from Kyushu. We identified three predominant genotype profiles in the tested area sharing high relatedness with genotype profiles of strains isolated in European countries. MAH was the most common NTM in pigs from Kyushu and exhibited high diversity, with new strain-derived genotypes. KEY WORDS: genotyping, Kyushu, mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR), Mycobacterium avium subsp. hominissuis, nontuberculous mycobacteria Mycobacterium avium subsp. hominissuis (MAH), belonging to the M. avium complex (MAC), is the most frequently encountered nontuberculous mycobacteria (NTM). MAH strains are maintained or persist in humans, other animals, and the environment. In humans, NTM cause pulmonary nontuberculous mycobacterial disease (PNTMD) [19, 27] , the incidence of which is increasing worldwide, including Japan [17, 19] . Pigs are the animals most susceptible to MAC infection, especially MAH [1, 10, 16, 18] . Pig breeding environments (bedding materials, water, and facilities used in pig husbandry) are a well-known source of MAH infection [16, 21] . In fact, MAH strains isolated from humans were found to be genetically similar to those in pigs in Japan [15] . MAH infection in pigs is characterized by granulomatous lesions in the lymph nodes of the digestive system [3]. Since most pigs do not show any clinical signs of infection, visceral organs, including lesions, are excluded from processing by macroscopic inspection at the slaughterhouse. An increase in the number of affected pigs will result in severe economic losses. Another problem associated with meat inspection is the inability to identify etiological agents other than by examining for macroscopic lesions. Furthermore, it is also quite difficult to determine the route of pathogen invasion in a pig farm, and the mode of pathogen propagation between individual animals. Mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) is a useful technique for characterizing the genetic diversity of isolates of MAC [4, 20] , M. avium subsp. paratuberculosis [8, 31] , and MAH [24] [25] [26] isolated from humans, other animals, and the environment. Eight MIRU-VNTR loci (292, X3, 25, 47, 3, 7, 10, and 32) can