26S rDNA-based phylogenetic investigation of Japanese cattle-associated Prototheca zopfii isolates.

The study has been conducted to assess the applicability of partial 26S ribosomal DNA sequence for the phylogenic analysis of P.zopfii and to arrive relationships between specific genotype of P.zopfii and clinical mastitis. The phylogenetic analysis indicated that all genotype 2 isolates were grouped into the cluster of type strain of P.zopfii. Thus, all mastitis isolates in Japan were identified as P.zopfii genotype 2 and were independent of the cluster of the genotype 1 isolates. In one clinical case, a fecal isolate could not be identified by the 18S rDNA-based genotype specific PCR-assay and appeared to belong to a same cluster with the type strain of P. blaschkeae by 26S rDNA analysis. The isolate was the first isolation in Japan.