Parvoviruses are ubiquitous pathogens that cause fatal disease in cats. Feline panleukopenia virus (FPV) is a primitive virus reported first and canine parvovirus (CPV) evolved from FPV and was reported later. Both induce disease in cats and dogs with correlative signs. FPV in domestic cats is genetically diverse and some strains may differ from those used for vaccination. In this study, a virus of FPV strain, ABT/MVC/2022/FPV/001, was identified from a fecal sample of the suspected cat with severe haemorrhagic gastroenteritis. The phylogenetic analysis and complete genome sequence of the strain share 99.75% nucleotide identity with FPV variant MH559110 belonging to Tamil Nadu, India. The results also reveal similarities to strains isolated from Italy, Belgium, and China. The deduced amino acid sequence of isolated strain revealed specific amino acid substitution (Pro5Ala, Phe6Val, His7Gln, Asn9Asp, Lys16Arg, Lys19Arg, Asn52Lys, Gly58Trp, Thr66Ser, Lys67Arg, Leu70His, Asn373Asp and Ala390Thr) which differed from MH559110 and other strains. The complete genomic analysis revealed that the FPV strain circulating in India is evolving rapidly with unique antigenic variations between field FPV, CPV and vaccine strains which may be the major cause for vaccine failure in vaccinated cats.
UNASSIGNED: The online version contains supplementary material available at 10.1007/s13337-023-00854-7.

Feline core vaccines strongly recommended for all cats are against Feline panleukopenia virus (FPV), Felid herpesvirus type 1 (FeHV-1), and Feline calicivirus (FCV), but cats can be classified as low- and high-risk based on their lifestyle. The aim of this study was to determine the actual seroprotection against FPV, FeHV-1, and FCV in a large cohort of Italian cats by using the VacciCheck test. A total of 740 cats (567 owned and 173 stray cats; 435 vaccinated and 305 unvaccinated) were analyzed for Protective Antibody Titers (PATs). Differences related to origin, sex, age, breed, FIV/FeLV status, health status, and time elapsed since last vaccination were evaluated. Less than half of the entire cohort (36.4%) had PATs for all three diseases simultaneously, increasing to 48.6% if weak positive values were also considered and 50.3% when considering only the 435 vaccinated cats. Particularly, antibodies were detected against FCV, FPV, and FeHV-1 at protective titers (PATs) in 78.6%, 68.1, and 49.1% of the cats, respectively. In general, owned, neutered, and adult FIV- and/or FeLV-negative cats were the most protected categories, even if not always for the three viruses. Most cats maintained high PATs for 3 years or longer after vaccination against FPV and FCV but not FeHV-1. Long-lasting protective immunity persisted for many years after the last vaccination (more than 18 years in the oldest cats). Nevertheless, since not all cats were protected after so many years and for all pathogens, checking protection via antibody titration could be the best choice to prevent immunity breakdowns. The discussion also focuses on the reliability of antibody titration for the two URTD (upper respiratory tract disease) viruses which, unlike for FPV, is not widely accepted as a valid index of protection.

Feline panleukopenia virus (FPV) is the causative agent of hemorrhagic gastroenteritis in feline animals. FPV has been evolving over time, and there have been several different strains of the virus identified. Some of these strains may be more virulent or more resistant to current vaccines than others, which highlights the importance of ongoing research and monitoring of FPV evolution. For FPV genetic evolution analysis, many studies focus on the main capsid protein (VP2), but limited information is available on the nonstructural gene NS1 and structural gene VP1. In the present study, we firstly isolated two novel FPV strains circulating in Shanghai, China, and performed full-length genome sequencing for the desired strains. Subsequently, we focused on analyzing the NS1, VP1 gene, and the encoding protein, and conducted a comparative analysis among the worldwide circulating FPV and Canine parvovirus Type 2 (CPV-2) strains, which included the strains isolated in this study. We found that the 2 structural viral proteins, VP1 and VP2, are splice variants, and VP1 has a 143 amino-acid-long N-terminal compared to VP2. Furthermore, phylogenetic analysis showed that divergent evolution between FPV and CPV-2 virus strains were clustered mostly by country and year of detection. In addition, much more continuous antigenic type changes happened in the process of CPV-2 circulating and evolution compared to FPV. These results stress the importance of the continuous study of viral evolution and provide a comprehensive perspective of the association between viral epidemiology and genetic evolution.