Análise molecular de cepas de campo de parvovírus canino tipo 2 e eficiência de neutralização viral de anticorpos gerados por vacinas comerciais e experimentais

Abstract

Canine Parvovirus Type 2 (CPV-2) is a virus that undergoes evolutionary changes due to nucleotide substitutions, which consequently lead to amino acid alterations in its genome, primarily in the VP2 protein, resulting in gastroenteric clinical signs, mainly in young and unvaccinated dogs. Regarding the immunization of dogs against CPV-2, it is suggested that vaccine failure in puppies may be related to the suppression of the immune response induced by maternal antibodies. Different brands of vaccines are available in Brazil, raising questions about the efficacy of domestic vaccines compared to imported ones. Therefore, the analysis of vaccine quality is of utmost importance to assess their effectiveness. This study was conducted to elucidate, through in vivo tests, the ability of antibodies generated by vaccines marketed in the southern region of Brazil, including both domestic and imported brands, to neutralize the virus. Additionally, field strains were obtained in collaboration with clinics in the Serra Gaúcha and metropolitan region of Porto Alegre to determine the predominant variants and the vaccination status of dogs with canine parvovirus. Furthermore, bioinformatics tools were also used to determine the main circulating variants in Brazil over the past 10 years, accessed through the GenBank platform. Thus, sequence alignment was performed in the MEGA11 program, a phylogenetic tree was constructed in the FigTree v1.4.4 program, and the predominant regions with amino acid substitutions were determined, both in circulating strains and in commercially sequenced vaccines from a previous study. The analysis concluded with an evaluation of the structural protein VP2 in the ChimeraX program, visualizing the electrostatic and hydrophobic points of the presented sites.The study identified the predominance of the CPV-2a variant, followed by CPV-2c and CPV-2b, respectively, highlighting changes in sites 44, 101, 267, 297, 300, 305, 324, 375, 426, and 440, with alterations in charge and hydrophobicity in the VP2 protein. In the phylogenetic tree, the vaccines were observed to cluster in the clade together with the ancestral strain, CPV-2b and CPV-2c variants were grouped in the same clade, and CPV-2a in a separate clade. Finally, questions were raised about the efficacy of the vaccines available in the southern region of Brazil, as different titers of neutralizing antibodies were observed in the in vivo results. [resumo fornecido pelo autor]