ID09 - Atovaquone Resistance M121I Polymorphism in Babesia gibsoni Isolates from Dogs

Abstract:

Background: Babesia gibsoni is a global pathogen of clinical importance in dogs. Resistance to atovaquone, based on the cytochrome b gene M121I mutation, has been increasingly identified in the United States, Japan, China, and India.

Objectives: To determine B. gibsoni proportion positive in a canine sample set collected in Hong Kong, and to validate a molecular test in the B. gibsoni detected samples for the single nucleotide polymorphism G363T/A causing the amino acid change in codon 121 from methionine to isoleucine (M121I). Animals: A total of 56 anonymized canine remnant whole blood samples were evaluated with a vector-borne disease (VBD) pathogen qPCR panel, including qPCR tests for B. gibsoni and the M121I Atovaquone resistance polymorphism.

Methods: Nucleic acid extracts were analyzed using a hydrolysis probe-based real-time PCR (qPCR) test for canine VBD pathogens, the M121I polymorphism, and an internal sample control. The M121I qPCR hydrolysis probe was specific for the G363T/A polymorphism. The cytochrome b gene G363T/A polymorphism was confirmed by Sanger sequencing. Frequency calculations were performed for: overall Babesia spp., B. gibsoni, and the G363T/A polymorphism.

Results: Babesia spp. were detected in 66.1% (37/56) samples. Of these, the majority detected as B. gibsoni (86.5%, 32/37), with 25% (8/32) detected for the G363T/A polymorphism, and confirmed by Sanger sequencing. VBD pathogen detection was described (Table).

Conclusions: Babesia gibsoni, and concurrent atovaquone resistance (M121I polymorphism), were widely detected in this cohort. Our work describes, and validates, a VBD qPCR panel that enables accurate pathogen detection, and targeted antimicrobial treatment, in dogs.