Relatedness of structures of a major immunogen in Trichomonas vaginalis isolates

1994

J Virol

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Some isolates of Trichomonas vaginalis carry a double-stranded RNA virus (TVV) and undergo phenotypic variation between surface expression and cytoplasmic expression of a prominent immunogen (P270). Only trichomonads with TVV express P270 on the surface. Northern (RNA) blots using a specific cDNA encoding the repeat element of the phenotypically varying P270 immunogen as a probe showed accumulation of P270 transcript only in isolates with TVV (V+) in contrast to isolates without the virus (V-). To test further the influence of virus infection on P270 mRNA expression, Vprogeny, derived from the parental V+ isolates, were tested. Trichomonads of Vprogeny, like the fresh clinical V-isolates, also showed no accumulation of P270 mRNA. By immunoblotting with a monoclonal antibody to the key repeated epitope of P270, it was found that V-organisms had quantitatively less immunoreactive protein than the parental V+ isolates. Although V+ and V-isolates contained proteins immunoreactive with the monoclonal antibody to P270, it was necessary to test for the presence of the P270 gene among all the isolates. As expected, Southern blots demonstrated that V+ and V-trichomonads possessed the gene encoding P270. These data suggest that the double-stranded RNA virus of T. vaginalis is involved in the regulation of P270 mRNA accumulation.

supporting

confidence: 91%

mentioning

confidence: 62%

Trichomonas vaginalis with a double-stranded RNA virus has upregulated levels of phenotypically variable immunogen mRNA

Khoshnan

1994

J Virol

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“…The three segments migrated between 5 and 4 kbp. Isolates ATCC 30001 and NYH 286 have been extensively studied (2,3,19,20,22). T0686-II, T042, and T046 are fresh clinical isolates.…”

Section: Resultsmentioning

confidence: 99%

Multiple double-stranded RNA segments are associated with virus particles infecting Trichomonas vaginalis

Khoshnan

1993

J Virol

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Previous studies demonstrated that some isolates of the sexually transmitted protozoan Trichomonas vaginalis are infected with a nonsegmented, double-stranded RNA (dsRNA) virus. A reexamination of the total dsRNA extracted from several virus-harboring isolates indicated the presence of at least three dsRNAs with sizes ranging from 4.8 to 4.3 kbp. The double-stranded nature of each of the three segments was determined by hybridization experiments using riboprobes of opposite polarities obtained from cDNA generated to each of the segments. All three segments were present in agar clones originating from single organisms of T. vaginalis isolates, suggesting that the three segments were not the result of a mixed population of trichomonads harboring different sizes of dsRNA. The three segments were associated with CsCl-purified virus particles, as evidenced by electron microscopy, and RNase treatment of the preparation containing virus particles did not destroy the dsRNAs. Finally, the individual dsRNA segments were purified for use as probes to determine whether the three dsRNAs shared any sequence homology. Each end-labeled dsRNA segment did not cross-hybridize to any of the other two segments, a finding consistent with the hybridization of labeled cDNAs to only the segments from which they were derived. These results show that the coding capacity of the dsRNA virus may be at least three times greater than that estimated earlier and illustrates further the complexity of this virus-parasite interrelationship.

“…This was defined on the basis of surface versus cytoplasmic expression of a repertoire of high-M r immunogens (1,2,4,5). The monoclonal antibody (MAb) C20A3 recognized an epitope tandemly repeated within the highly immunogenic surface protein termed P270 (6)(7)(8). Analyses by flow cytofluorometry and fluorescence-activated cell sorting (FACS) of fresh clinical isolates revealed heterogeneous immunoreactivity, such as fluorescent and nonfluorescent subpopulations by indirect immunofluorescence with MAb (4,6).…”

mentioning

confidence: 99%

Iron Modulates Phenotypic Variation and Phosphorylation of P270 in Double-Stranded RNA Virus-Infected Trichomonas vaginalis

1999

Infect Immun

Trichomonas vaginalis infected with a double-stranded RNA virus undergoes phenotypic variation on the basis of surface versus cytoplasmic expression of the immunogenic protein P270. Examination of batch cultures by flow cytofluorometry with monoclonal antibody (MAb) to P270 yields both fluorescent and nonfluorescent trichomonads. Greater numbers and intensity of fluorescent organisms with surface P270 reactive with MAb were evident in parasites grown in medium depleted of iron. Placement of iron-limited organisms in medium supplemented with iron gave increased numbers of nonfluorescent trichomonads. Purified subpopulations of trichomonads with and without surface P270 obtained by fluorescence-activated cell sorting reverted to nonfluorescent and fluorescent phenotypes when placed in high- and low-iron media, respectively. No similar regulation by iron of P270 was evident among virus-negative T. vaginalis isolates or virus-negative progeny trichomonads derived from virus-infected isolates. Equal amounts of P270 were detectable by MAb on immunoblots of total proteins from identical numbers of parasites grown in low- and high-iron media. Finally, P270 was found to be highly phosphorylated in high-iron parasites. Iron, therefore, plays a role in modulating surface localization of P270 in virus-harboring parasites.