Antiviral Activity of Nitazoxanide and Miltefosine Against FeHV-1 In Vitro

Feline herpesvirus type 1 (FeHV-1) is a primary pathogen in cats responsible for respiratory and ocular signs. There are presently no antiviral drugs that are officially licensed for veterinary use in several countries. Consequently, veterinarians must depend on off-label antivirals designed for human use. Recent advances in virus-host cell interaction have resulted in new insights into FeHV-1 replication, establishing the importance of the PI3K/Akt axis. The aim of this study was to employ this new information to assess the efficacy of two compounds whose activities involve this pathway. The antiviral properties of miltefosine and nitazoxanide were examined using seven different concentrations, evaluating cell viability and viral titers after 24 h of infection. Furthermore, selected concentrations were supplied at different time points to investigate the influence of the timing of the addition. The best results were obtained when the drugs were added both before and after viral adsorption (in particular for nitazoxanide). Each compound was further investigated by real-time PCR, western blot, and immunofluorescence. Nitazoxanide was the most effective treatment, reducing the expression of viral glycoproteins as measured by western blot and immunofluorescence, as well as reducing the release of virions in the supernatant (measured by real-time PCR). Moreover, treatment with nitazoxanide and miltefosine was associated with a decrease in Akt phosphorylation. This work emphasized the significance of comprehending the pathways necessary for viral replication and their use in the assessment of novel and effective antivirals.