Richter M, Schudel L, Tobler K et al: Clinical, virological, and immunological parameters associated with superinfection of latently with FeHV-1 infected cats, Vet Microbiol 138:205, 2009.
Feline herpesvirus (FHV) is a common respiratory and ocular pathogen of cats. It may be associated with recurrent ocular disease, even in vaccinated cats. These investigators examined the role of superinfecting FHV strains in recurrent disease. To do this, they genetically engineered a FHV strain to fluoresce, so that it could be distinguished from wild type strains of the virus. It was used to superinfect nine cats that were latently infected with a wild type strain of FHV. Active infection of the mutant virus in the inoculated cats was documented, but reactivation of the latent wild type strain did not occur. Following infection, no change in the clinical condition of the cats occurred. A rise in antibody titer and increased interferon production were noted. Thus, superinfection did induce an immune response, but was not associated with reactivation of latent virus. The authors concluded that vaccination of latently infected cats does not lead to reactivation of the latent virus, nor clinical disease. Sixteen months after superinfection, the cats were temporarily immunosuppressed, and assessed for reactivation of FHV. Mild signs were observed in all cats. Interestingly, only the wild type virus was identified; there was no evidence of mutant virus reactivation. Thus, it was not clear that the mutant virus was able to establish latency. The clinical disease observed was due to the reactivation of the latent wild type strain. The researchers continue to investigate the usefulness of this mutant marker virus to establish the pathogenesis of recurrent FHV disease. [MK]
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