Physicochemical Characterization of Human Herpesvirus 6 Infectivity

Shiraki, Kimíyasu; Mukai, T.; Okuno, Toshiomi; Yamanishi, Koichi; Takahashi, Michiaki

doi:10.1099/0022-1317-72-1-169

Cited by 5 publications

(4 citation statements)

References 27 publications

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“…In the present study, the kinetics of total virus number, virus within virus-Ig complexes formed after infection with influenza A virus and infectious virus was investigated in nasal secretions of naive mice and mice previously immunized with different influenza A and B viruses. Total virus number or the virus number within the immune complexes was estimated on the basis of viral genome copy number measured by Q-PCR, which approximates to virus particle number estimated by EM (Watson et al, 1963;Shiraki et al, 1991). The A/PR8 viral titre that corresponded to 61 viral genome copies measured by Q-PCR or 23 viral particles counted by EM produced 1 p.f.u.…”

Section: Discussionmentioning

confidence: 99%

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Total viral genome copies and virus–Ig complexes after infection with influenza virus in the nasal secretions of immunized mice

Yoshikawa

Matsuo

et al. 2004

Journal of General Virology

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The kinetics of infectious virus (p.f.u.), total virus and virus-Ig complex formation following influenza A/PR8 (H1N1) viral infection was examined in the nasal secretions of naive mice and mice immunized with A/PR8, A/Yamagata (H1N1), A/Guizhou (H3N2) and B/Ibaraki influenza viruses. The total number of virus particles and the number within virus-Ig complexes, captured in advance using an anti-mouse Ig-coated plate, were determined on the basis of viral genome copy number using quantitative RT-PCR. The kinetics of infectious and total virus particle formation, the latter of which increased by 10 3-10 4-fold above infectious virus numbers, showed that virus elimination from the nasal area was earlier in A/PR8, A/Yamagata and A/Guizhou-X virus-immunized mice, in decreasing order, compared with naive mice. Early virus elimination correlated with the level of A/PR8 virus-reactive antibodies in immunized mice. Virus elimination coincided with the appearance of virus-Ig complexes shortly after infection. This result suggested that antibodies led to the formation of immune complexes in a dose-dependent manner together with a reduction in number of infectious virus particles. The fact that a large number of virus particles was observed in immune complexes for a wide range antibody levels made it difficult to detect slight differences in virus number within the immune complexes, depending on antibody level. These results suggested that the formation of virus-Ig complexes in virus-immunized mice shortly after infection is involved in early virus elimination, which is determined by the strength of protective immunity against challenge viruses.

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Section: Discussionmentioning

confidence: 99%

“…Virus particles were counted by the loop-drop method (Watson et al, 1963;Shiraki et al, 1991). Briefly, the virus solution was mixed with a standard latex particle solution (Stadex, 100 nm diameter; JSR Corporation).…”

Section: Methodsmentioning

confidence: 99%

Total viral genome copies and virus–Ig complexes after infection with influenza virus in the nasal secretions of immunized mice

Yoshikawa

Matsuo

et al. 2004

Journal of General Virology

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“…3). This may reflect, at least in part, the fact that the extracellular-particle-to-infectivity ratio for HHV-6B has been estimated at roughly 10 3 :1 to 10 4 :1 (26). Thus, of the relatively small amount of plasmid DNA found in extracellular virus particles (Fig.…”

Section: Fig 8 Sequences Of Trs-containing Plasmids (A)mentioning

confidence: 97%

“…One previously reported difference between these viruses is their relative particle/infectivity ratios. Permissive cell cultures infected with both viruses yield similar total numbers of extracellular virus particles (10 8 to 10 9 /ml), but the infectious yield of HHV-6B particles is between 1 and 3 log units lower than that for HSV-1 (26). In this regard, HHV-6B is rather more similar to another betaherpesvirus, human cytomegalovirus, which has been reported to have a particle/infectivity ratio of approximately 10 3 :1 (2).…”

Section: Fig 8 Sequences Of Trs-containing Plasmids (A)mentioning

confidence: 98%

Functional Identification and Analysis of cis -Acting Sequences Which Mediate Genome Cleavage and Packaging in Human Herpesvirus 6

Deng

Dewhurst

1998

J Virol

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Sequences present at the genomic termini of herpesviruses become linked during lytic-phase replication and provide the substrate for cleavage and packaging of unit length viral genomes. We have previously shown that homologs of the consensus herpesvirus cleavage-packaging signals, pac1 and pac2, are located at the left and right genomic termini of human herpesvirus 6 (HHV-6), respectively. Immediately adjacent to these elements are two distinct arrays of human telomeric repeat sequences (TRS). We now show that the unique sequence element formed at the junction of HHV-6B genome concatemers (pac2-pac1) is necessary and sufficient for virally mediated cleavage of plasmid DNAs containing the HHV-6B lytic-phase origin of DNA replication (oriLyt). The concatemeric junction sequence also allowed for the packaging of these plasmid molecules into intracellular nucleocapsids as well as mature, infectious viral particles. In addition, this element significantly enhanced the replication efficiency of oriLyt-containing plasmids in virally infected cells. Experiments revealed that the concatemeric junction sequence possesses an unusual, S1 nuclease-sensitive conformation (anisomorphic DNA), which might play a role in this apparent enhancement of DNA replication—although additional studies will be required to test this hypothesis. Finally, we also analyzed whether the presence of flanking viral TRS had any effect on the functional activity of the minimal concatemeric junction (pac2-pac1). These experiments revealed that the TRS motifs, either alone or in combination, had no effect on the efficiency of virally mediated DNA replication or DNA cleavage. Taken together, these data show that the cleavage and packaging of HHV-6 DNA are mediated by cis-acting consensus sequences similar to those found in other herpesviruses, and that these sequences also influence the efficiency of HHV-6 DNA replication. Since the adjacent TRS do not influence either viral cleavage and packaging or viral DNA replication, their function remains uncertain.

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Phenotypic and genetic polymorphisms among human herpesvirus-6 isolates from North American infants

et al. 1992

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Physicochemical Characterization of Human Herpesvirus 6 Infectivity

Cited by 5 publications

References 27 publications

Total viral genome copies and virus–Ig complexes after infection with influenza virus in the nasal secretions of immunized mice

Total viral genome copies and virus–Ig complexes after infection with influenza virus in the nasal secretions of immunized mice

Functional Identification and Analysis of cis -Acting Sequences Which Mediate Genome Cleavage and Packaging in Human Herpesvirus 6

Phenotypic and genetic polymorphisms among human herpesvirus-6 isolates from North American infants

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