Bovine leukemia virus genotype surveillance in cattle at a slaughterhouse in Aichi Prefecture, Japan, in 2019 using polymerase chain reaction combined with restriction fragment length polymorphism.

Polymerase chain reaction (PCR) combined with restriction fragment length polymorphism (RFLP) is commonly used for genotyping bovine leukemia virus (BLV) in slaughterhouses. However, unclassified BLV genotypes have been sporadically reported. To assess the current status of BLV genetic characterization in cattle, PCR-RFLP was performed on blood samples of 170 cattle (84 Japanese Black, 60 Japanese Black x Holstein, and 26 Holstein) from 17 farms (5 prefectures) at a slaughterhouse in Aichi Prefecture in 2019. A total of 65 samples (38.2%) were BLV positive, and genotype 1 was the most predominant (56/65 samples), followed by genotypes 3 (6 samples) and 5 (1 sample), and two unclassified samples. No relationship between the genotypes and breeds was observed. Sequence and phylogenetic analyses demonstrated that unclassified BLV genotypes clustered with genotype 1 sequences were, therefore, not new genotypes.

Changes in antimicrobial resistance phenotypes and genotypes in Streptococcus suis strains isolated from pigs in the Tokai area of Japan.

Streptococcus suis strains isolated from porcine endocarditis and tonsils in the Tokai area of Japan during 2004-2007 and 2014-2016 (n=114) were tested for antimicrobial susceptibility and distribution of selected resistance genes. No strains showed resistance to penicillin, ampicillin, cefotaxime, meropenem, vancomycin, and levofloxacin. High resistance to tetracycline (80.7%), clindamycin (65.8%), erythromycin (56.1%), and clarithromycin (56.1%) was observed. In chloramphenicol and sulfamethoxazole-trimethoprim, there was a trend towards increased resistance between the first (2004-2007) and second (2014-2016) periods. tet(O) and erm(B) genes were the most frequently detected, and tet(M) and mef(A/E) genes were only detected in strains isolated during 2014-2016. These results indicate that chloramphenicol and sulfamethoxazole-trimethoprim resistance, and tet(M) and mef(A/E) genes emerged in S. suis of this area after 2014.