Epidemiological analysis of worldwide bovine, canine and human clinical Prototheca isolates by PCR genotyping and MALDI-TOF mass spectrometry proteomic phenotyping.

This study presents information on the phenotypic and genotypic characterization of clinical Prototheca spp. isolates obtained from different geographic regions. Of 350 isolates studied, 342 came from cattle, six from canines and two from humans. Phenotypic characterization was carried out by a matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) proteomic analysis. The peptide extraction that was used for this analysis included the additional steps of washing and sonication to increase the yield of peptide. Genotypic analysis was conducted using species- and genotype-specific primers. The study revealed that among the cattle isolates, 310 (90.6%) belonged to Prototheca zopfii genotype 2, 30 (8.8%) to P. blaschkeae, and two (0.6%) to P. zopfii genotype 1. P. zopfii genotype 2 is the principal etiological agent of protothecal mastitis in cattle regardless of the geographic region. Similarly, all canine and human isolates also belonged to the P. zopfii genotype 2, suggesting that this is probably the most virulent species of the genus. The role of P. blaschkeae needs further epidemiologic studies to ascertain its etiologic role in bovine mastitis. To the best of our knowledge, this is the first comprehensive study on phenotypic and genotypic characterization of P. zopfii and P. blaschkeae isolates originating from diverse clinical specimens from different countries.