Molecular identification of Prototheca algae in 11 sick dogs

Abstract

Protothecosis is an uncommon disease caused by algae of the genus. In dogs, the infection is usually first localized to the colon but has the propensity to later disseminate hematogenously to many other organs, with marked tropism for the eyes and central nervous system. Diagnosis is established by culture and/or evidence oforganisms in cytologic or histologic preparations. Species characterization, however, requires molecular investigations. Our laboratory set up a real-time PCR targeting portion D1/D2 of the 28S rRNA for identification ofspecies from both positive cultures (of rectal swabs and urine) and formalin-fixed, paraffin-embedded tissue.,, andwere characterized in 11 dogs with systemic or cutaneous protothecosis.identifications were phylogenetically consistent with the new taxonomy proposed for this genus based on the mitochondrial cytochromegene. As a pilot study, we screened feces and rectal scrapes from 200 asymptomatic dogs, using 2 cohorts of stray and owned animals, to determine the prevalence of intestinal carriage ofspp. The-negative results from both cohorts of healthy dogs suggest that predisposing factors related to the host probably contribute more to the acquisition of clinical disease than exposure to contaminated environments.