The Complete cDNA Sequence of a Type II Trichomonas vaginalis Virus

Abstract

Trichomonas vaginalis viruses (TVV), which may regulate P270 gene expression in the protozoan pathogen T. vaginalis, are a group of divergent double-stranded (ds) RNA viruses. In the present study, the complete 4674-bp cDNA sequence of a 4.6-kb ds RNA from a newly identified TVV2-1 isolate was determined. The sequence of the plus-strand mRNA contains four open reading frames, which encode overlapping cap and pol genes in the reading frame 2 and reading frame 1, respectively, and two putative serine-threonine-rich basic proteins VP3 and VP4 in the third reading frame. An 85-kDa capsid protein and a 160-kDa CAP-POL fusion protein were identified in crude viruses by Western blotting experiments using antisera raised against gene-specific oligopeptides. In conjunction with the presence of a potential ribosomal slippery heptanucleotide G GGC CCC within the overlap of the cap and pol genes, these observations suggest that the pol gene of TVV2-1 is translated via a -1 ribosomal frameshifting event during translation of the cap gene. Our results also provide insight into the conservation among divergent dsRNA species from TVV and suggest that the genome of TVV2-1 may encode two extra genes in addition to the cap and pol genes.

Double-stranded RNA viral infection in Cuban Trichomonas vaginalis isolates

“…The TVV genome encodes for capsid protein and RNA-dependent RNA polymerase [13,14]. Alderete et al [15] found the genetic variations that exist within the capsid protein gene; this may explain the diversity in this non-segmented dsRNA virus.…”

Double-stranded RNA virus in Korean Isolate IH-2 of Trichomonas vaginalis

“…The conserved sequence motifs of 5'-ACTCAACATT-3' and 5'-CTATACCTTC-3' of TVV 1-1 and 1-5 isolates were also observed at the 5' and 3' termini of TVV IH-2, respectively. The identity percentage of the genomic dsRNA of TVV IH-2 was 80%, when compared to TVV 1-1 and 1-5 (Tai and Ip, 1995;Su and Tai, 1996), but only 42%, when compared to the TVV 2-1 and 3 isolates (Bessarab et al, 2000). It harbored 2 overlapping open reading frames (ORF 1 and ORF 2) coupled with a ribosomal frame shift event on the plus strand viral RNA (Fig.…”

“…In order to evaluate the evolutionary relationship between TVV IH-2 and previously reported TVV isolates (TVV1-1, 1-5, 2-1 and 3) (Tai and Ip, 1995;Su and Tai, 1996;Bessarab et al, 2000), multiple sequence alignment and bootstrap analyses of RdRp and capsid proteins were conducted using the CLUSTAL W program on the DDBJ Web server (http://www.ddbj.nig. ac.jp) (Thompson et al, 1994).…”

“…TVV was primarily described as a uniform population of icosahedral particles, 33 nm in diameter (Wang and Wang, 1986). However, electron microscopic studies have recently shown that several types of virus-like particles (VLPs) could simultaneously infect T. vaginalis isolates (Bessarab et al, 2000;Benchimol et al, 2002aBenchimol et al, , 2002bBenchimol et al, , 2002c. Although the most abundant type of virus detected was the aforementioned icosahedral particles, the number of dsRNA segments varied from 1 to 3 in different TVV isolates.…”

“…Four species of genomic dsRNAs have been cloned from the TVV isolates 1-1, 1-5, 2-1 and 3, and their genetic information has been previously reported (Tai and Ip, 1995;Su and Tai, 1996;Bessarab et al, 2000) (GenBank Accession no. U08999, U57898, AF127178, and AF325840).…”