RESUMO
The prophage Lv1, harbored by a vaginal Lactobacillus jensenii isolate, was induced by several different anticancer, antimicrobial, and antiseptic agents, suggesting that they contribute to the adverse vaginal effects associated with their therapeutic use. Of special interest with respect to its novelty was the inducing effect of nonoxynol-9, a non-ionic detergent commonly used as a spermicide. The Lv1 genome consists of a 38,934-bp dsDNA molecule with cohesive ends, in which 48 ORFs were recognized, and is organized into functional modules. Lv1 belongs to the family Siphoviridae and, more precisely, to the proposed Sfi21-like genus. The capsid-tail junction of the Lv1 virions is fragile such that most particles become disrupted, suggesting that the virus is defective and thus unable to generate fertile progeny. However, genome analysis did not provide evidence of the defective nature of the prophage, other than the finding that its genome is shorter than those of other, related, phages. Further analysis indicated that prophage Lv1 suffered deletions in its right half to the extent that it no longer fulfill the minimum packaging limits, thereby generating the observed unstable particles (AU)
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Assuntos
Humanos , Feminino , Genoma Viral , Lactobacillus/virologia , Prófagos/isolamento & purificação , Ativação Viral , Anti-Infecciosos Locais/metabolismo , Antineoplásicos/metabolismo , DNA Viral/química , DNA Viral/genética , Eletroforese em Gel de Poliacrilamida , Lactobacillus/isolamento & purificação , Microscopia Eletrônica de Transmissão , Prófagos/classificação , Prófagos/genética , Prófagos/fisiologia , Vagina/microbiologia , Replicação ViralRESUMO
Vaginal disorders associated with systemic chemotherapy arise by direct inhibition of the resident microbiota (dominated by lactobacilli) or, possibly, by induction of prophages harbored in their genomes, leading to cell lysis. In the present study, proficient Lactobacillus phages could not be isolated from vaginal exudates. However, lysogeny appeared to be widespread, although about half of the strains harbored prophage sequences that were not responsive to SOS activation. In other cases, prophage induction was achieved, but viable phages were not generated, despite the fact that the induced supernatants of some strains were bactericidal. In one case, this activity was accompanied by the production of a bacteriophage subsequently identified as a member of the family Siphoviridae (isometric capsid and long non-contractile tail). Most of the lactobacilli tested generated hydrogen peroxide, which acted as an inducer of the SOS response, suggesting that H2O2 selects for strains that harbor SOS-insensitive, defective prophages, which are thus unable to promote vaginal lactobacilli phage-induced lysis (AU)
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