Molecular Detection and Phylogenetic Characterization of CPV-2c in Apparently Healthy Domestic Cats in the Guadalajara Metropolitan Area, Mexico

Abstract

Carnivore protoparvovirus 1 variants (CPV-2a, CPV-2b, CPV-2c) have progressively expanded their host range to domestic cats (Felis catus), causing subclinical infection or panleukopenia-like disease. CPV-2c dominates among dogs in Western Mexico, but its presence in the local feline population had not been investigated. A cross-sectional survey was conducted (2018–2022) in 210 apparently healthy domestic cats from five municipalities of the Guadalajara Metropolitan Area, Jalisco, Mexico. Genomic DNA from EDTA-anticoagulated blood was screened by generic protoparvovirus PCR; positive samples were characterized by CPV-2-specific VP2 PCR and Sanger sequencing, with variant classification based on VP2 residue 426, and phylogenetic relationships assessed by maximum-likelihood analysis (T92+I model; 1000 bootstrap replicates). Carnivore protoparvovirus 1 DNA was detected in 14/210 cats (6.7%); 13/14 sequenced isolates were classified as CPV-2c (Glu426, >99% nucleotide identity), clustering with regional canine strains and showing greatest affinity with Uruguayan isolates. In a Firth bias-reduced multivariable model adjusting for age and vaccination status, shared litter box use remained independently associated with detection (adjusted OR 18.03; 95% CI 3.30–98.58); the age association was attenuated after adjustment, suggesting incomplete vaccination, rather than age itself, as the more proximal risk factor. Free-roaming/outdoor access and hunting behavior showed direct crude associations with detection (OR 3.82 and 7.22, respectively). These findings show that cats can harbor CPV-2c DNA in blood without clinical signs, phylogenetically linked to local canine strains, underscoring the need for integrated CPV-2 surveillance across companion species; however, whether infected cats can transmit the virus remains undetermined.