Rapid formation of specific neutralizing antibodies to HAV following a single dose of an inactivated hepatitis A virus vaccine

ABSTRACTHepatitis A virus (HAV) is an unusual picornavirus that is released from cells cloaked in host-derived membranes. These quasi-enveloped virions (eHAV) are the only particle type circulating in blood during infection, whereas only nonenveloped virions are shed in feces. The reason for this is uncertain. Hepatocytes, the only cell type known to support HAV replicationin vivo, are highly polarized epithelial cells with basolateral membranes facing onto hepatic (blood) sinusoids and apical membranes abutting biliary canaliculi from which bile is secreted to the gut. To assess whether eHAV and nonenveloped virus egress from cells via vectorially distinct pathways, we studied infected polarized cultures of Caco-2 and HepG2-N6 cells. Most (>99%) progeny virions were released apically from Caco-2 cells, whereas basolateral (64%) versus apical (36%) release was more balanced with HepG2-N6 cells. Both apically and basolaterally released virions were predominantly enveloped, with no suggestion of differential vectorial release of eHAV versus naked virions. Basolateral to apical transcytosis of either particle type was minimal (<0.02%/h) in HepG2-N6 cells, arguing against this as a mechanism for differences in membrane envelopment of serum versus fecal virus. High concentrations of human bile acids converted eHAV to nonenveloped virions, whereas virus present in bile from HAV-infectedIfnar1−/−Ifngr1−/−andMavs−/−mice banded over a range of densities extending from that of eHAV to that of nonenveloped virions. We conclude that nonenveloped virions shed in feces are derived from eHAV released across the canalicular membrane and stripped of membranes by the detergent action of bile acids within the proximal biliary canaliculus.IMPORTANCEHAV is a hepatotropic, fecally/orally transmitted picornavirus that can cause severe hepatitis in humans. Recent work reveals that it has an unusual life cycle. Virus is found in cell culture supernatant fluids in two mature, infectious forms: one wrapped in membranes (quasi-enveloped) and another that is nonenveloped. Membrane-wrapped virions circulate in blood during acute infection and are resistant to neutralizing antibodies, likely facilitating HAV dissemination within the liver. On the other hand, virus shed in feces is nonenveloped and highly stable, facilitating epidemic spread and transmission to naive hosts. Factors controlling the biogenesis of these two distinct forms of the virus in infected humans are not understood. Here we characterize vectorial release of quasi-enveloped virions from polarized epithelial cell cultures and provide evidence that bile acids strip membranes from eHAV following its secretion into the biliary tract. These results enhance our understanding of the life cycle of this unusual picornavirus.

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Hepatitis A Virus-Specific Immunoglobulin A Mediates Infection of Hepatocytes with Hepatitis A Virus via the Asialoglycoprotein Receptor

Journal of Virology ◽

10.1128/jvi.74.23.10950-10957.2000 ◽

2000 ◽

Vol 74 (23) ◽

pp. 10950-10957 ◽

Cited By ~ 85

Author(s):

Andreas Dotzauer ◽

Ulrike Gebhardt ◽

Karen Bieback ◽

Ulrich Göttke ◽

Anja Kracke ◽

...

Keyword(s):

Gastrointestinal Tract ◽

Neutralizing Antibodies ◽

Hepatitis A ◽

Hepatitis A Virus ◽

Immunoglobulin A ◽

Asialoglycoprotein Receptor ◽

Primary Hepatocytes ◽

Mouse Hepatocyte ◽

Specific Immunoglobulin ◽

Bile Fluid

ABSTRACT The mechanisms underlying the hepatotropism of hepatitis A virus (HAV) and the relapsing courses of HAV infections are unknown. In this report, we show for a mouse hepatocyte model that HAV-specific immunoglobulin A (IgA) mediates infection of hepatocytes with HAV via the asialoglycoprotein receptor, which binds and internalizes IgA molecules. Proof of HAV infection was obtained by detection of HAV minus-strand RNA, which is indicative for virus replication, and quantification of infectious virions. We demonstrate that human hepatocytes also ingest HAV–anti-HAV IgA complexes by the same mechanism, resulting in infection of the cells, by using the HepG2 cell line and primary hepatocytes. The relevance of this surrogate receptor mechanism in HAV pathogenesis lies in the fact that HAV, IgA, and antigen-IgA complexes use the same pathway within the organism, leading from the gastrointestinal tract to the liver via blood and back to the gastrointestinal tract via bile fluid. Therefore, HAV-specific IgA antibodies produced by gastrointestinal mucosa-associated lymphoid tissue may serve as carrier and targeting molecules, enabling and supporting HAV infection of IgA receptor-positive hepatocytes and, in the case of relapsing courses, allowing reinfection of the liver in the presence of otherwise neutralizing antibodies, resulting in exacerbation of liver disease.

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Immunogenicity of Hepatitis A Virus Vaccine in Primates

The Journal of Infectious Diseases ◽

10.1093/infdis/161.3.586 ◽

1990 ◽

Vol 161 (3) ◽

pp. 586-587 ◽

Cited By ~ 3

Author(s):

R. K. Chaudhary ◽

T. Mo

Keyword(s):

Virus Vaccine ◽

Hepatitis A ◽

Hepatitis A Virus

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Successful Boosting of a DNA Measles Immunization with an Oral Plant-Derived Measles Virus Vaccine

Journal of Virology ◽

10.1128/jvi.76.15.7910-7912.2002 ◽

2002 ◽

Vol 76 (15) ◽

pp. 7910-7912 ◽

Cited By ~ 46

Author(s):

Diane E. Webster ◽

Michelle L. Cooney ◽

Zhongjun Huang ◽

Damien R. Drew ◽

Ian A. Ramshaw ◽

...

Keyword(s):

Immune Response ◽

Single Dose ◽

Global Health ◽

Virus Vaccine ◽

Neutralizing Antibodies ◽

Measles Virus ◽

Vaccination Strategy ◽

Health Concern ◽

Dna Immunization ◽

Edible Plant

ABSTRACT Despite eradication attempts, measles remains a global health concern. Here we report results that demonstrate that a single-dose DNA immunization followed by multiple boosters, delivered orally as a plant-derived vaccine, can induce significantly greater quantities of measles virus-neutralizing antibodies than immunization with either DNA or plant-derived vaccines alone. This represents the first demonstration of an enhanced immune response to a prime-boost vaccination strategy combining a DNA vaccine with edible plant technology.

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