Abstract
There are two types of feline coronaviruses that can be distinguished by serology and sequence analysis. Type I viruses, which are prevalent in the field but are difficult to isolate and propagate in cell culture, and type II viruses, which are less prevalent but replicate well in cell culture. An important determinant of coronavirus infection, in vivo and in cell culture, is the interaction of the virus surface glycoprotein with a cellular receptor. It is generally accepted that feline aminopeptidase N can act as a receptor for the attachment and entry of type II strains, and it has been proposed that the same molecule acts as a receptor for type I viruses. However, the experimental data are inconclusive. The aim of the studies reported here was to provide evidence for or against the involvement of feline aminopeptidase N as a receptor for type I feline coronaviruses. Our approach was to produce retroviral pseudotypes that bear the type I or type II feline coronavirus surface glycoprotein and to screen a range of feline cell lines for the expression of a functional receptor for attachment and entry. Our results show that type I feline coronavirus surface glycoprotein fails to recognize feline aminopeptidase N as a functional receptor on three continuous feline cell lines. This suggests that feline aminopeptidase N is not a receptor for type I feline coronaviruses. Our results also indicate that it should be possible to use retroviral pseudotypes to identify and characterize the cellular receptor for type I feline coronaviruses.
Highlights
Coronaviruses are enveloped, plus-stranded RNA viruses that cause widespread disease in humans and animals
The main conclusion of the experiments reported here is that fAPN does not function as a receptor for the attachment and entry of Feline coronavirus (FCoV) type I viruses
This is based upon the inability of retroviral pseudotypes bearing the FCoV type I S glycoprotein to transduce cells that express fAPN and can be transduced by retroviral pseudotypes bearing the FCoV type II S glycoprotein
Summary
Coronaviruses are enveloped, plus-stranded RNA viruses that cause widespread disease in humans and animals. They tend to infect just one or a few closely related species and in their natural host exhibit marked tissue tropism. Feline coronavirus (FCoV) infection is extremely common in cats. Natural infections with FCoV are usually transient, a significant percentage of infections may become persistent (Addie & Jarrett, 2001). Most infections are asymptomatic or result in mild, self-limiting gastrointestinal disease, and in these cases the causative agent is known as feline enteric coronavirus (FECV). In a small percentage (,5 %) of animals, a fatal multisystemic, immune-mediated disease occurs and this is Supplementary tables are available with the online version of this paper
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