Nucleotide sequence and expression of the capsid protein gene of feline calicivirus

Abstract

The sequence of the 3'-terminal 2,486 bases of the feline calicivirus (FCV) genome was determined. This region of the FCV genome, from which the 2.4-kb subgenomic RNA is derived, contained two open reading frames. The larger open reading frame, found in the 5' end of the subgenomic mRNA, contained 2,004 bases encoding a polypeptide of 73,467 Da. The smaller open reading frame, encoded in the 3' end of the mRNA, was composed of 318 bases, encoding a polypeptide of 12,185 Da. The AUG initiation codon of the second open reading frame overlapped the UGA termination codon of the first, with the sequence AUGA. The nucleotide sequence of the region containing this overlap resembles the-1 frameshift sequences of the retroviruses. The 5' end of the 2.4-kb subgenomic RNA was mapped by primer extension analysis. There were two apparent transcription initiation points, both of which were 5' to the AUG initiation codon of the large open reading frame. Transcription from these sites yielded RNA transcripts with 5' nontranslated leader regions of 17 and 18 bases. The total length of the 2.4-kb subgenomic RNA was 2,375 bases (from the 5'-most start site) excluding the poly(A) tail. Edman degradation of the purified capsid protein of FCV showed that the capsid protein was encoded by the large open reading frame. Western immunoblot analysis of FCV-infected cells using a feline anti-FCV antiserum demonstrated that translation of the capsid protein was detectable at 3 h postinfection and continued to accumulate until 8 h postinfection, the last time examined.

Genomic 3′ terminal sequence comparison of three isolates of rabbit haemorrhagic disease virus

“…Following this a small (58n) non-coding region extends to the poly-A tail a, the 3' terminus of the virus RNA. This structure is consistent with that of a calicivirus and is present in all feline calicivirus (FCV) strains sequenced, and is highly conserved [14][15][16].…”

“…It is unlikely therefore that this open reading frame directs a major antigen of the virus (Milton, unpublished observations). Neiii et al [16] suggest that this ORF may be translated as a fusion protein, joined to the major capsid gene product, by ribosome frameshifting. They suggest the sequence AUUAUGA, located at the gene junction, eoulcl direct this event [16].…”

Pushing the limits of the scanning mechanism for initiation of translation

“…A few other reported dicistronic mRNAs await testing. Wold et al, 1995;Ziff, 1985 Parvovirus: adeno-associated Capsid protein A Capsid proteins B/C Splicing Muralidhar et al, 1994 Hepatitis B virus Core protein S proteins (envelope) Promoter switch Schaller and Fischer, 1991 Retrovirus: avian, murine Gag (capsid) protein Env protein Splicing e Pawson et al, 1977;Van Zaane et al, 1977 Retrovirus: human foamy Gag (capsid) protein Pol precursor Splicing Jordan et al, 1996 Lentivirus: HIV-1 Tat Rev and Nef f Splicing Schwartz et al, 1992 Alphavirus: Semliki Forest Nonstructural proteins Capsid protein Internal promoter Glanville et al, 1976;Strauss and Strauss, 1994 Calicivirus: feline g Nonstructural proteins Capsid protein Independent replication Carter, 1990;Neill et al, 1991 a The silent downstream cistron identified in the third column is expressed only upon being moved closer to the 5 0 end via production of a second, shorter mRNA. Translation of most genes derived from these viruses follows straightforward predictions of the scanning mechanism, although occasional deviations have been reported.…”

Conformational Changes in the Capsid of a Calicivirus upon Interaction with Its Functional Receptor

“…All 24 mutants contained one or two point mutations within the major capsid protein (Table 3), giving a total of 20 unique mutations. Three of these mutations were present in the leader sequence of the capsid, which is cleaved from the capsid precursor protein during capsid assembly by a virusencoded proteinase (4,33,54); however, the mutants that contained mutations in the leader sequence also had an additional mutation in another region of the capsid protein. Several residue changes were found in more than one mutant.…”