Microevolution of tick-borne encephalitis virus in course of host alternation.
Two tick-borne encephalitis (TBE) virus variants were studied: mouse brain-adapted strain EK-328 and its derivate adapted to Hyalomma marginatum ticks. The tick-adapted virus exhibited small-plaque phenotype and slower replication in PEK cells, higher yield in ticks, decreased neuroinvasiveness in mice, increased binding to heparin-sepharose. A total of 15 nucleotide substitutions distinguished genomes of these variants, six substitutions resulted in protein sequence alterations, and two were in 5'NTR. Two amino acid substitutions in E protein were responsible for the observed phenotypic differences. Data obtained during reverse passaging of the tick-adapted virus in vivo and in vitro suggest that TBE virus exists as a heterogeneous population that contains virus variants most adapted to reproduction in either ticks or mammals. Host switch results in a change in the ratio of these variants in the population. Plaque purification of the tick-adapted virus resulted in the prompt emergence of new mutants with different virulence for mammals.
Romanova
Lidiya Iu
LIu
M.P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical Sciences, Moscow Region 142782, Russia.
Gmyl
Anatoly P
AP
Dzhivanian
Tatiana I
TI
Bakhmutov
Denis V
DV
Lukashev
Alexander N
AN
Gmyl
Larissa V
LV
Rumyantsev
Alexander A
AA
Burenkova
Ludmila A
LA
Lashkevich
Vasilii A
VA
Karganova
Galina G
GG
D020121:5' Untranslated Regions / Q000235:genetics; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D002460:Cell Line; D002490:Central Nervous System / Q000821:virology; D004669:Encephalitis Viruses, Tick-Borne / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D004675:Encephalitis, Tick-Borne / Q000821:virology*; D019143:Evolution, Molecular; D016679:Genome, Viral / Q000235:genetics; D026863:Ixodidae; D051379:Mice; D008969:Molecular Sequence Data; D013552:Swine; D010948:Viral Plaque Assay; D014774:Virulence / Q000235:genetics*; D014779:Virus Replication
D020121:5' Untranslated Regions