The internal open reading frame within the nucleocapsid gene of mouse hepatitis virus encodes a structural protein that is not essential for viral replication - PubMed (original) (raw)

The internal open reading frame within the nucleocapsid gene of mouse hepatitis virus encodes a structural protein that is not essential for viral replication

F Fischer et al. J Virol. 1997 Feb.

Abstract

The coronavirus mouse hepatitis virus (MHV) contains a large open reading frame embedded entirely within the 5' half of its nucleocapsid (N) gene. This internal gene (designated I) is in the +1 reading frame with respect to the N gene, and it encodes a mostly hydrophobic 23-kDa polypeptide. We have found that this protein is expressed in MHV-infected cells and that it is a previously unrecognized structural protein of the virion. To analyze the potential biological importance of the I gene, we disrupted its expression by site-directed mutagenesis using targeted RNA recombination. The start codon for I was replaced by a threonine codon, and a stop codon was introduced at a short interval downstream. Both alterations created silent changes in the N reading frame. In vitro translation studies showed that these mutations completely abolished synthesis of I protein, and immunological analysis of infected cell lysates confirmed this conclusion. The MHV I mutant was viable and grew to high titer. However, the I mutant had a reduced plaque size in comparison with its isogenic wild-type counterpart, suggesting that expression of I confers some minor growth advantage to the virus. The engineered mutations were stable during the course of experimental infection in mice, and the I mutant showed no significant differences from wild type in its ability to replicate in the brains or livers of infected animals. These results demonstrate that I protein is not essential for the replication of MHV either in tissue culture or in its natural host.

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References

1. Arch Virol. 1992;125(1-4):141-60 - PubMed
1. Anal Biochem. 1979 Sep 15;98(1):132-5 - PubMed
1. Lab Anim Sci. 1992 Dec;42(6):593-8 - PubMed
1. Virology. 1993 Mar;193(1):520-3 - PubMed
1. Lab Anim Sci. 1993 Feb;43(1):15-28 - PubMed

The internal open reading frame within the nucleocapsid gene of mouse hepatitis virus encodes a structural protein that is not essential for viral replication - PubMed (original) (raw)