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At least 19 recordsLinked to original sources
PubMed1999

Infection of chicken embryonic fibroblasts by measles virus: adaptation at the virus entry level.

Measles virus (MV) has a tropism restricted to humans and primates and uses the human CD46 molecule as a cellular receptor. MV has been adapted to grow in chicken embryonic fibroblasts (CEF) and gave rise to an attenuated live vaccine. Hallé and Schwarz MV strains were compared in their ability to infect both simian Vero cells and CEF. Whereas both strains infected Vero cells, only the CEF-adapted Schwarz strain was able to efficiently infect CEF. Since the expression of the human MV receptor CD46 rendered the chicken embryonic cell line TCF more permissive to the infection by the Hallé MV strain, the MV entry into CEF appeared to be a limiting step in the absence of prior MV adaptation. CEF lacked reactivity with anti-CD46 antibodies but were found to express another protein allowing MV binding as an alternative receptor to CD46.

Adaptation, Physiological↗
PubMed2000

Immune and pathophysiological processes in baboons experimentally infected with Ebola virus adapted to guinea pigs.

The dynamics of pathophysiological and immunological parameters monitored in monkeys Papio hamadryas infected with the guinea pig-adapted Ebola virus strain demonstrated that this viral strain preserved its virulence for monkeys and caused the disease with characteristic features similar to those caused by non-adapted Ebola virus. However, certain previously unknown patterns have been observed: (1) prolongation of the febrile period by two days; (2) extended period was characterized by stability of serum biochemical parameters; (3) marked vacuolization of the neutrophil cytoplasm; (4) appearance of juvenile lymphocytes on day 3 and by the end of the disease; and (5) a considerable increase in the spontaneous mononuclear proliferation (along with a decrease in the mitogen-induced proliferation) during the terminal stage of infection. The severity of pathological coagulation was found to correlate with the activity of serum cytokines IFN-alpha and TNF-alpha: their activities increased about 250- and 100-fold, respectively. There was significant alteration in the activity of natural killer cells, that dropped by the time of animal death.

Adaptation, Physiological↗
PubMed1985

Encephalitis induced in non-human primates by canine distemper virus adapted to human neural cells.

The Onderstepoort strain of canine distemper virus (CDV) adapted to human oligodendroglioma, neuroblastoma and glioblastoma cells, was intracerebrally inoculated into cynomolgus monkeys. All the three viruses caused periventricular encephalitis involving the brain stem. When the neurovirulence of these viruses were compared in terms of clinical signs and histopathological changes, the oligodendroglioma-adapted virus showed the neurovirulence of the highest degree inducing degeneration of axons and glial cells. Chronic encephalitis was also observed. The neuroblastoma-adapted virus induced predominantly nerve-cell degeneration although clinically this virus showed slightly lower degree of neurovirulence than the oligodendroglioma-adapted viruses. The glioblastoma-adapted virus showed clinically much lower neurovirulence than the other two viruses; all monkeys infected with this virus survived and produced high level of antibody in most cases. Histopathologically degeneration of axons and glial cells was characteristics although the incidence was less frequent than the oligodendroglioma-adapted virus. Predominant involvement of nerve cells by neuroblastoma-adapted virus and predominant involvement of axon and glial cells by oligodendroglioma-adapted virus and by glioblastoma-adapted virus suggest that in vitro tropism of the virus to neural cells is partially reflected on tropism of the virus in the CNS.

Animals↗
PubMed1990

[Molecular basis of retrovirus adaptation: nucleotide sequence of Rous sarcoma virus adapted to duck cells].

The host range of retroviruses is rather complex and specific. It is controlled by the products of viral structural genes that interact with the determinants both on the surface and within the cell. The possibility to infect and transform duck embryo fibroblasts is shown for the Prague strain of chicken Rous sarcoma virus (subgroup C), though virus production in these cells is restricted. However, after the 6th passage the "adapted" virus gave the titre practically the same as it was for chicken embryo fibroblasts. Provirus of RSV adapted to the duck embryo fibroblasts and integrated into host DNA was isolated from the library of nucleotide sequences of duck embryo fibroblasts transformed by this virus. The nucleotide sequence of such provirus was determined. The alterations in gp85 coding region of the env gene which proved to be the result of recombination with endogeneous RAV-0 sequences were shown. The formation of viral particles with rather high titre was induced by the proviral transfection on both chicken and duck embryo fibroblasts. The contribution of the revealed alterations in the genome of transformation active virus and possible participation of its td mutant in the adaptation to the new host are discussed.

Adaptation, Physiological↗
PubMed1988

Characterization of canine distemper viruses adapted to human neural cells.

The biochemical characteristics of canine distemper virus (CDV) adapted to three human neural cells (glioblastoma, oligodendroglioma, and neuroblastoma cells) were compared with those of the unadapted original virus. The specific gravity of the virions and nucleocapsids of the original and the three adapted viruses were not different. The molecular weights of genomic RNA and messenger RNAs encoding H, F, P, and NP proteins of the adapted viruses as estimated by Northern blot hybridization were similar to those of the original virus. By T1-resistant oligonucleotide analysis of the genomic RNA, the glioblastoma- and the neuroblastoma-adapted viruses gave two more spots than the original virus; the oligodendroglioma-adapted virus had a pattern identical to that of the original virus. By two-dimensional gel electrophoresis of virion proteins, we found a difference in the isoelectric point of the viral envelope proteins H and F between the original and the adapted viruses. These results suggest that viral genomic changes occurred during adaptation, resulting in the alteration of viral envelope proteins.

Adaptation, Physiological↗
PubMed1983

Canine distemper infection in mice: characterization of a neuro-adapted virus strain and its long-term evolution in the mouse.

The Onderstepoort strain of canine distemper virus (CDV) which has been adapted to newborn Swiss mice was used in a study in weanling mice. Intracerebral inoculation of newborn mice with either the parent or mouse-adapted virus strain led to mortality in 100% of the animals. In weanling mice the parent virus produced less than 10% mortality, whereas the mouse-adapted strain killed approximately 40% of the animals and this was not dose-dependent. Although a meningitis was observed in the surviving mice, the occurrence of viral antigens was less widespread in the brain of weanling mice than in the brain of newborn mice, and could not be detected more than 5 months after infection. In long-term experiments two phenomena were observed. At 4 to 6 months post-infection up to 30% of the mice became obese; however, no viral antigens were detected in the brains. At 13 to 17 months post-infection a number of mice became paralysed and virus antigen could be detected in the brain and lymph glands; however, infectious virus could not be isolated. These observations are discussed in relation to neurological infection and metabolic disease.

Animals↗
PubMedDate not supplied

[Molecular basis and mechanisms of Influenza viruses adaptation to reproduction in murine lung].

Analyzes modern data on the role of individual segments of genome in acquisition of virulence during influenza virus adaptation to reproduction in the lungs of mice. Discusses the significance of molecular mechanisms (loss of potential glycosylation site(s), optimum pH of HA-mediated fusion, beta-inhibitor sensitivity, pH-dependent association/dissociation of M1 protein with viral RNP, and host factors) involved in adaptation of influenza virus to a new host.

Adaptation, Biological↗
PubMed2000

Are RNA viruses adapting or merely changing?

RNA viruses and retroviruses fix substitutions approximately 1 million-fold faster than their hosts. This diversification could represent an inevitable drift under purifying selection, the majority of substitutions being phenotypically neutral. The alternative is to suppose that most fixed mutations are beneficial to the virus, allowing it to keep ahead of the host and/or host population. Here, relative sequence diversification of different proteins encoded by viral genomes is found to be linear. The examples encompass a wide variety of retroviruses and RNA viruses. The smoothness of relative divergence spans quasispeciation following clonal infection, to variation among different isolates of the same virus, to viruses from different species or those associated with different diseases, indicating that the majority of fixed mutations likely reflects drift. This held for both mammalian and plant viruses, indicating that adaptive immunity doesn't necessarily shape the relative accumulation of amino acid substitutions. When compared to their hosts RNA viruses evolution appears conservative.

Adaptation, Physiological↗
PubMed1989

Studies on the genetic basis of human influenza A virus adaptation to mice: degrees of virulence of reassortants with defined genetic content.

A highly virulent mouse-adapted variant of influenza virus A/Aichi/2/68 (H3N2) was crossed either with the original A/USSR/90/77 (H1N1) influenza virus strain or with its mouse-adapted, moderately mouse virulent variant. The reassortants were characterized with respect to their genetic content and pneumovirulence for mice. The reassortants fell into three categories: avirulent, highly virulent (resembling in this respect the parent A/Aichi/2/68 virus) and moderately virulent (resembling the mouse-adapted A/USSR/90/77 parent virus). The analysis of the parental origin of the genes of 6 reassortants allowed to suggest that changes in the HA gene and in a polymerase gene (most likely, PB1) were necessary for the acquisition of virulence by the A/USSR/90/77 virus in the course of adaptation to mice, whereas the changes in two other polymerase genes as well as in the genes NA and NS were not involved. The low degree of pathogenicity characteristic of the mouse-adapted A/USSR/90/77 virus was determined by gene(s) other than HA.

Adaptation, Physiological↗
PubMed1983

Characterization of canine distemper viruses adapted to neural cells and their neurovirulence in mice.

Interaction of the Onderstepoort strain of canine distemper virus (CDV) with three established human neural cells, i.e. IMR-32 neuroblastoma, 118-MGC glioma and KG-1 oligodendroglioma, was examined, and adaptation of CDV to these cells was also attempted. The unadapted virus was found to grow at relatively low titers in the three neural cells inducing moderate to minimal cytopathic effects (CPE). The virus was successfully grown at high titers in these cells after 8 to 10 passages. Biological characteristics such as growth rate, morphology of CPE and plaque size changed after adaptation. Analysis by SDS-polyacrylamide gel electrophoresis, however, failed to show any difference in the molecular weight of component proteins among the unadapted and three adapted viruses. Inbred DDD strain of mice developed clinical signs after intracerebral inoculation with the unadapted virus but most of them survived with histological lesions of encephalitis. Neuroblastoma-adapted virus induced only transient clinical signs in some animals with mild encephalitic lesions in the gray matter. Increases in neurovirulence were found for viruses adapted to glioma and oligodendroglioma cells. Almost all mice inoculated with these two viruses at 3 weeks of age died within 8 days with histological lesions consisting of hyperemia, edema, severe degeneration of nerve cells and a few giant cells. Demyelinating lesions in the absence of inflammatory changes were observed in the cerebellum, pons and medulla oblongata of animals inoculated with oligodendroglioma-adapted virus.

Animals↗
PubMed1999

Pathogenicity of Sendai viruses adapted into polarized MDCK cells.

Apically and basally released Sendai viruses (SeV) were obtained after infection of polarized Madin-Darby canine kidney (MDCK) cells grown on permeable membrane culture inserts. After 20 passages of adaptation in MDCK cells, we compared their in vivo and in vitro pathogenicity with the parental Mol-strain of SeV. These viruses had comparable in vitro pathogenicity, but the in vivo pathogenicities were varied. The apically released MDCK-adapted virus showed comparable pathogenicity with the parental virus, in contrast with the basally released MDCK-adapted virus, which showed in vivo attenuation.

Animals↗
PubMedDate not supplied

[Safety and high immunogenicity for children 3 to 15 of a mono- and a divaccine from recombinant influenza A/Brazil /11/78 (H1N1) and A/Bangkok/1/79 (H3N2) viruses obtained from a special donor attenuation base--the cold-adapted virus A/Leningrad/134/47/57 (H2N2)].

The data on complete safety and high immunogenic potency of intranasal live influenza vaccine from the recombinant A/Brazil/11/78 (H1N1) and A/Bangkok/1/79 (H3N2) strains prepared with a special donor of attenuation, a cold-adapted A/Leningrad/134/47/57 (H2N2) virus, have been obtained. The possibility of using a bivaccine from the recombinant strains constructed on the basis of a single donor of attenuation and inheriting from it most of the genes coding for nonglycosylated proteins was demonstrated. Administration of this bivaccine to children was not accompanied by any increase in the rate of postvaccination febrile reactions, but produced in the vaccinees an intensive immune response to the antigenic components of the vaccine which was in agreement with the data obtained after separate administration of monovaccines.

Adaptation, Physiological↗
PubMedDate not supplied

[Immunochemical characteristics of the antigens of a variant tick-borne encephalitis virus adapted to Hyalomma plumbeum ticks].

A comparative study of immunochemical properties of a preparation of the virion antigen of a variant of tick-borne encephalitis (TBE) virus adapted to H. plumbeum ticks (clone 718/574) and the parental TBE strain revealed the following features: (1) immunoelectrodiffusion test revealed no immunoprecipitation rockets directed towards cathode in the clone 718/574 preparation; anodic precipitates differed in shape from those of the parental strain; (2) diffuse precipitation in agar showed a reaction of incomplete identity between the virion antigen of clone 718/574 and the parental strain antigen, the clone 718/574 antigen forming only one precipitation band in contrast to two precipitation bands of the parental strain; (3) immune electron microscopy demonstrated a peculiar nature of the halo-overlay by immunoglobulins of clone 718/574 virions differing from that of the parental strain.

Adaptation, Physiological↗
PubMed1985

Development and characterization of cold-adapted viruses for use as live virus vaccines.

Representative viruses from twelve RNA and two DNA virus genera have been successfully adapted to growth at sub-optimal temperature (cold-adapted). In almost every case, there was a correlation between acquisition of the cold-adaptation phenotype and loss of virulence in the normal host whether animal or man. Overall, the best method of cold adaptation to develop a live virus vaccine line appeared to be a stepwise lowering of the growth temperature allowing time for multiple lesions to occur and/or be selected. In addition, the starting virus should be a recent isolate not as yet adapted to a tissue culture host and the cold-adaptation process should then occur in a host heterologous to the virus' normal host. These viruses have been reviewed in the light of their cold-adaptation method and successful production of an attenuated line as virus vaccine candidate. Finally, detailed information is presented for the cold-adaptation process in influenza virus.

Acclimatization↗