Small ruminant lentivirus and Mycobacterium avium subsp. paratuberculosis: co-infection prevalence and preliminary investigation on genetic resistance to both infections in a Garfagnina goat flock

摘要

Small ruminant lentiviruses (SRLVs) are a heterogeneous group of viruses of sheep, goats and wild ruminants, causing persistent infection and responsible of chronic degenerative disease of joints, lungs, udder and central nervous system in small ruminants. Mycobacterium avium subsp. paratuberculosis (MAP) is also a major production-limiting disease, which causes a chronic infection of ruminants. The disease causes persistent diarrhea, progressive weight loss, debilitation, anemia, and eventually death. Both SRLVs and MAP are widespread in small ruminants in many countries. The aim of this study was to estimate the prevalence of SRLVs and MAP co-infection in a Garfagnina goat flock consisting of 269 females and 20 males and located in Garfagnana district (Tuscany, Italy). All adult females were tested for MAP and SRLVs infection. Thirty-six out of 269 animals in total resulted positive for one or both infections. A total of 27 goats (10%) were positive to MAP and 21 goats (7.8%) were positive to SRLV. The apparent prevalence of co-infection was 4.5%, counting 12 goats positive for both infections. No significant association was found between subjects seropositive to SRLV and MAP. To investigate possible genetic influences on susceptibility or resistance of goats for both disease, all co-infected animals were compared with no infected animals (control group, 12 goats). Blood samples were collected and 12 STR markers (MAF65, SRCRSP5, INRA023, MCM527, CSRD247, SRCRSP23 OarFCB20, TGLA53, INRA005, INRA063, ETH10, ILSTS87) were investigated. For each marker, allele and genotypes frequencies between the two groups of animals were compared using the chi-square test and Fisher's exact tests. No statistical differences in STR alleles or genotypes frequency were observed between healthy animals and co-infected animals. Future works may include replication of this study with a larger number of animals to try to identify candidates genes for the genetic resistance to both infections.