2 New HCV ABSTRACTS

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J Infect Dis. 2011 Jan;203(2):196-206.

The human fetal immune response to hepatitis C virus exposure in utero.

Babik JM, Cohan D, Monto A, Hartigan-O'Connor DJ, McCune JM.

Division of Experimental Medicine.

Abstract

Background. Although the rate of mother-to-child transmission of hepatitis C

virus (HCV) is low, the effect of HCV exposure in utero on the fetal immune

system is unknown. Methods. Umbilical cord blood was obtained from 7 neonates

born to HCV-seropositive, HCV RNA-positive women and 8 neonates born to

HCV-seronegative women. Cord blood mononuclear cells were analyzed by

immunophenotyping and by intracellular cytokine staining after HCV-specific and

polyclonal stimulation. Plasma was analyzed for anti-HCV immunoglobulin M (IgM),

cytokine/granzyme concentrations, and indoleamine 2,3-dioxygenase (IDO)

activity. Results. HCV-exposed neonates had significantly lower levels of

regulatory T cells expressing HLA-DR, lower CD4(+) and CD8(+) T cell activation,

and lower plasma levels of pro-inflammatory markers than did controls. However,

CD4(+) and CD8(+) T cells from HCV-exposed neonates had higher IFN-ã production

in response to polyclonal stimulation than did T cells from controls. IDO

activity was similar between groups. No HCV-specific T cell responses or

anti-HCV IgM were detected in any neonates. Conclusions. HCV-exposed neonates

showed a relative suppression of immune activation and pro-inflammatory markers,

which was counterbalanced by an increased production capacity for IFN-ã. These

results suggest that HCV encounters the fetal immune system in utero, and alters

the balance between suppressive and pro-inflammatory responses.

PMID: 21288819 [PubMed - in process]

J Virol. 2011 Feb 2. [Epub ahead of print]

Novel mutations in a tissue-culture adapted HCV strain improve infectious virus

stability and markedly enhance infection kinetics.

Pokrovskii MV, Bush CO, Beran RK, MF, Cheng G, Tirunagari N, Fenaux M,

Greenstein AE, Zhong W, Delaney WE 4th, son MS.

Gilead Sciences, Inc., City, CA 94404.

Abstract

Hepatitis C virus (HCV) establishes persistent infections and leads to chronic

liver disease. It only recently became possible to study the entire HCV life

cycle due to the ability of a unique cloned patient isolate (JFH-1) to produce

infectious particles in tissue culture. However, despite efficient RNA

replication, yields of infectious virus particles remain modest. This presents a

challenge for large-scale tissue-culture efforts such as inhibitor screening.

Starting with a J6/JFH-1 chimeric virus we used serial passaging to generate a

virus with substantially enhanced infectivity and faster infection kinetics

compared to the parental stock. The selected virus clone possessed seven novel

amino acid mutations. We analyzed the contribution of individual mutations and

identified three specific mutations, core K78E, NS2 W879R, and NS4B V1761L,

which were necessary and sufficient for the adapted phenotype. These three

mutations conferred a 100-fold increase in specific infectivity compared to the

parental J6/JFH-1 virus, and media collected from cells infected with the

adapted virus yielded infectious titers as high as 1 x 10(8) TCID50/ml. Further

analyses indicated that the adapted virus has longer infectious stability at

37°C compared to wild-type. Given that the adapted phenotype resulted from a

combination of mutations in structural and nonstructural proteins, these data

suggest that the improved viral titer are likely due to differences in virus

particle assembly that result in significantly improved infectious particle

stability . This adapted virus will facilitate further studies of the HCV life

cycle, virus structure, and high-throughput drug screening.

PMID: 21289124 [PubMed - as supplied by publisher]