Molecular Characterization of Prototheca strains isolated in China revealed the first cases of protothecosis associated with Prototheca zopfii genotype 1.

In this study, six strains of Prototheca isolated in China from human patients diagnosed as protothecosis and cows with mastitis were characterized by polymerase chain reaction (PCR) and nucleotide sequencing of the ribosomal RNA gene (rDNA) and by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). The results indicated that three strains isolated from the human patients were P. zopfii genotype 1, revealing the first cases of human protothecosis associated with P. zopfii genotype 1. The remaining three strains were shown to be P. zopfii genotype 2. Interestingly, one strain isolated from the cerebrospinal fluid of the human patient appeared to have both of the genotype 1- and 2-specific alleles in the small subunit (SSU) rDNA although it was classified by MALDI-TOF MS as genotype 2. For genotyping of certain strains of P. zopfii, it may be necessary to comprehensively evaluate the diversity in the SSU rDNA sequences and the MALDI-TOF MS results.