title: Killing of Trichomonas vaginalis by complement-mediated lysis is not associated with the presence of Trichomonas vaginalis virus.
abstract: We have examined the possible relationship between trichomonad killing by human serum and the presence of virus-encoded double-stranded ribonucleic acid in T. vaginalis (TVV). Indirect immunofluorescence assay revealed that non-immune serum (NIS) and T. vaginalis-immune serum (TVIS) had immunoglobulin G (IgG) antibody titres of 1:8 and 1:256, respectively, against T. vaginalis. Among the 12 isolates of T. vaginalis examined, 9 were infected with TVV. Upon long-term (> 9 months) culture, of the 9 infected isolates, 3 isolates lost the virus during the passage process. Five of 9 TVV-infected isolates were completely killed by 10% NIS while the other 4 TVV-infected isolates had viability over the range 22-81%. Three fresh non-TVV-infected isolates had viability over the range 12-89%. On the other hand, no trichomonads survived in the presence of 10% TVIS. Viability of the virus-lost isolates during long-term culture was not altered when compared with that of their corresponding fresh isolates. Heat-inactivated-NIS and -TVIS had no killing effect on trichomonads while absorbed-NIS and -TVIS (ATVIS) had a similar killing effect to NIS. Further studies on the role of antibody and complement in the killing of trichomonads by serum revealed no significant difference in trichomonad viability between treatments of Mg2+-ethylene glycol-bis-(beta-aminoethyl ether)- N,N,N1,N1- tetraacetic acid (Mg(2+)-EGTA)-TVIS and of Mg(2+)-EGTA-ATVIS. Zymosan-treated ATVIS did not kill trichomonads but zymosan-treated TVIS had a marked killing effect.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Parasitology and Tropical Medicine, National Defense Medical Center, Taipei, Taiwan, Republic of China.
authors.forename: M F
authors.initials: MF
authors.lastname: Shaio
authors.forename: P R
authors.initials: PR
authors.lastname: Lin
authors.forename: C S
authors.initials: CS
authors.lastname: Lee
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D015941:Complement Hemolytic Activity Assay; D003170:Complement Pathway, Alternative; D003171:Complement Pathway, Classical; D003165:Complement System Proteins / Q000276:immunology*; D006801:Humans; D012328:RNA Viruses / Q000502:physiology*; D014246:Trichomonas vaginalis / Q000276:immunology* / Q000382:microbiology*
chemical_list: D000913:Antibodies, Protozoan; D003165:Complement System Proteins