RESUMO
Experiments with attenuated clones of Venezuelan equine encephalomyelitis virus and Eastern equine encephalomyelitis virus were carried out to study the regularities in changes of biological properties of virus in "undiluted" passages and in passages by subcultivation of small doses. In the latter case the biological activity of the virus remained at the initial low level but in "undiluted" passages it increased, due to accumulation in the population of clones with altered plaque phenotype and increased reproductive potential. In a number of cases this virus had a higher level of residual virulence than the original one. The evidence that the main source of virus variability in the "undiluted" passages lies, in genetic interaction in which defective virus takes part, is presented. Mixed infection with participation of defective interfering particles and the genetic interaction occurring in it are considered to be the mechanism which is conducive to restoration of biological activity of alphaviruses.
Assuntos
Alphavirus/fisiologia , Alphavirus/genética , Alphavirus/patogenicidade , Animais , Embrião de Galinha , Vírus Defeituosos/genética , Vírus da Encefalite Equina do Leste/genética , Vírus da Encefalite Equina do Leste/patogenicidade , Vírus da Encefalite Equina do Leste/fisiologia , Vírus da Encefalite Equina Venezuelana/genética , Vírus da Encefalite Equina Venezuelana/patogenicidade , Vírus da Encefalite Equina Venezuelana/fisiologia , Camundongos , Fenótipo , Interferência Viral , Ensaio de Placa Viral , Virulência , Cultura de Vírus/métodos , Replicação ViralRESUMO
Comparative data with regard to the properties of Venezuelan equine encephalomyelitis (VEE) virus isolated from HeLa carrier cultures by transfection in different cell cultures have been obtained. Introduction of DNA extracted from the carrier cultures into BHK-21 cell cultures resulted in production of an actively multiplying medium-plaque virus, and parallel addition of the same DNA preparations in chick fibroblast or monkey kidney cultures led to production of small-plaque virus with a low reproduction potential. The virus produced by transfection of BHK-21 cells differed from that produced in chick fibroblast and monkey kidney cultures in electrophoretic mobility of virion envelope proteins. The infection of these cultures with virions as well as infection with genome RNA did not result in production of differing virus variants. The importance of the experimental genetic data for the problem of the nature of the infectious principle of cellular DNA preparations and of the form of existence of viral genome in chronically infected cultures with infection of the integrative type is discussed.
Assuntos
Vírus da Encefalite Equina Venezuelana/genética , Encefalomielite Equina/microbiologia , Variação Genética , Transfecção , Animais , Embrião de Galinha , Doença Crônica , Vírus da Encefalite Equina Venezuelana/isolamento & purificação , Fibroblastos/microbiologia , Haplorrinos , Células HeLa/microbiologia , Humanos , Rim , Ensaio de Placa Viral , Cultura de VírusRESUMO
An acute infection of HeLa cell cultures with a ts mutant of Venezuelan equine encephalomyelitis (VEE) virus may have different outcomes ranging from formation of a chronic virus-carrier state to complete elimination of virus from the culture. One of the possibilities is also a short-time carrier state (up to 10 passages) of the virus genome apparently existing in the form of DNA-provirus. The carrier state of virus genetic material in this case is indicated by the infectivity of cellular DNA and the presence in it of sequences homologous to those of virion RNA. The genetic material of VEE virus in HeLa cell cultures with signs of infection of the integrative type is also demonstrable by its complementation with exogenous ts-mutants.
Assuntos
Vírus da Encefalite Equina Venezuelana/patogenicidade , Mutação , Animais , Sobrevivência Celular , Efeito Citopatogênico Viral , DNA/genética , Genes Virais , Células HeLa/microbiologia , Humanos , Hibridização de Ácido Nucleico , RNA Viral/genética , Virulência , Cultura de VírusRESUMO
Experiments were performed on pathogenicity of LPV oncornavirus and Mason-Pfizer-like virus for monkeys Macaca mulatta. The mixture of culture fluid and cell homogenate ultrafiltrates of virus-producing T-9 cell line was used as a source of LPV virus. The same materials derived from HEp-2 continuous cell line served as a source of Mason-Pfizer-like virus. As a control monkeys were inoculated with ultrafiltrates from human diploid cells. The clinical and pathomorphological analysis of experimental results leads to the conclusion, that only LPV virus induced different forms of haemacytoblastosis in monkeys that confirms our previous observations.
