Detection of neutralizing antibody to Feline herpesvirus type 1 in cat serum

Feline Herpesvirus-1 is a major pathogen that causes feline viral rhinotracheitis, pneumonia, and ocular diseases. This virus is transmitted through direct or indirect contact with secretions from infected cats. Approximately 80 % of infected cats establish lifelong latent infections, making FHV-1 a persistent and significant threat to feline health. Current control strategies mainly rely on antiviral medications and vaccines to mitigate disease severity and reduce viral transmission. However, the extent to which individual cats can develop protective immunity following FHV-1 infection or vaccination remains unclear. Therefore, in this study, a double-reporter FHV-1 was employed to detect neutralizing antibody titers in serum samples collected from 89 domestic cats. The results revealed that 93.75 % of unvaccinated cats exhibited a positive FHV-1-neutralizing antibody, whereas 82.19 % of the cats in the vaccinated group lacked detectable neutralizing antibodies, indicating individual variation in immune responses. Subsequent correlation analyses within the vaccinated group demonstrated that cats aged 3-12 months and aged ≥ 12 months were 11.32-fold and 9.22-fold more likely to exhibit viral suppression compared to those aged ≤ 3 months, respectively. These findings suggest that FHV-1 has a high natural infection rate, and vaccination can enhance the levels of neutralizing antibodies, although vaccine effectiveness varies among individuals. Therefore, the development of diverse vaccine formulations and the implementation of routine serological screening are crucial for disease control.