Traces of hepatitis B virus (HBV) genome can persist for years following recovery from hepatitis B. To determine overall duration, molecular characteristics, and pathological implications of this serologically undetectable form of hepadnaviral carriage, we have analyzed the expression of transcriptionally active virus genomes, their infectivity, and examined liver alterations during the natural lifespan of woodchucks convalescent from acute infection with HBVrelated woodchuck hepatitis virus (WHV). In this study, we document lifelong persistence of scanty amounts of replicating virus both in the liver and lymphatic system after spontaneous resolution of an episode of experimental hepadnaviral hepatitis. Antibodies to virus nucleocapsid (core) were found to be the most reliable immunovirological marker coexisting with occult infection. In the majority of convalescent woodchucks, serial liver biopsies showed protracted minimal to mild necroinflammation with periods of normal morphology; however, hepatocellular carcinoma (HCC) ultimately developed in 2 of 9 animals studied. Inocula derived from lymphoid cells of convalescent animals induced classical acute hepatitis in virus-naive woodchucks that progressed to chronic hepatitis and HCC in 1 of the animals, demonstrating infectivity and pathogenic competence of the carried virus. Our results reveal that low levels of infectious WHV and residual hepatic inflammation usually continue for life after resolution of hepatitis and that this recovery does not avert HCC development. They also demonstrate that, in addition to the liver, the lymphatic system is the site of the occult lifelong maintenance of replicating hepadnavirus. (HEPATOLOGY 1999;29:928-938.)Current evidence indicates that carriage of minute quantities of hepatitis B virus (HBV) genome can continue for years following complete clinical and serological recovery from acute hepatitis B. 1-5 In these convalescent patients, HBV DNA have been detected both in serum and in circulating lymphomononuclear cells, often despite the presence of neutralizing antibodies to virus envelope (hepatitis B surface antigen) 2,3,5 and a vigorous polyclonal HBV-specific cytotoxic T-cell response. 3,4,6 In addition, traces of hepatitis B surface antigen and HBV-DNA-reactive particles with physicochemical properties of intact virions have been detected in the circulation of some of the recovered individuals. 2 These findings imply that HBV eradication does not coincide with the rise of antivirusspecific humoral and cellular immune responses and with clinical resolution of acute hepatitis.It is expected that this serologically undetectable persistence of HBV may have important epidemiological and pathogenic implications, whose range has yet to be established. This assumption is based on a growing number of observations indicating that HBV infection can appear in recipients of organs from HBV serologically negative donors, [7][8][9][10][11][12] and that hepatocellular carcinoma (HCC) with integrated HBV genomic sequences can arise in ...

Summary During HIV infection, CD8 + T cells lacking the costimulatory molecule CD28 increase in number and proportion. This accumulation is associated with disease activity and possibly with CD8 + T-cell dysfunction. In this study, CD8 + CD28 + and CD8 + CD28 -T cells from 41 HIV-infected individuals at various stages of disease were compared in terms of HIV-specific cytotoxicity, TCR β V repertoire diversity, and cytokine production. We found that the CD28 phenotype of anti-HIV CTL evolves in parallel with disease progression and disease activity. Absolute numbers of CD4 + T cells and CD4 + /CD8 + T-cell ratios progressively decreased in 3 groups with an increasing prevalence of CD28 -HIV-specific CTL. Conversely, HIV replication levels progressively increased in parallel with the prevalence of CD28 -HIV-specific CTL. Repertoire diversity at the level of TCR β V gene family expression was maintained at normal levels for both CD28 + and CD28-T cells at all stages of infection. Diversity at the level of junctional length polymorphism was more restricted in the CD8 + CD28 -T-cell population, but this difference remained relatively constant through different stages of infection. Both CD28 + and CD28 -T cells produced IL-2 and IFN-γ , regardless of disease stage and/or the predominant CD28 phenotype of anti-HIV CTL.

The sequestration of cellular K(+) has been shown elsewhere to elicit a broad spectrum of antiviral activity. The obligatory, coupled cotransports of Na(+), K(+) and Cl(-) (NKCC1) and of Na(+) and K(+) (NKATPase) effect net cellular K(+) influx. We examined the effects of specific inhibitors of these transports; a cardiac glycoside (Digoxin) and a loop diuretic (Furosemide) on virus replication in vitro. The replication of the DNA viruses, herpes simplex virus, varicella zoster virus, human cytomegalovirus and adenovirus was inhibited. There was normal replication of the RNA virus encephalomyocarditis virus. Antiviral activities of both drugs were influenced by extracellular K(+). Antiviral effects were most potent when Digoxin and Furosemide were used in combination. Targeting the host cell in this way is fundamentally different to other antiviral drug developments to date and we propose the descriptive term Ionic Contra Viral Therapy (ICVT) for the purpose of definition. We believe that specific inhibitors of coupled K(+) transports merit controlled clinical trial for a broad spectrum of DNA virus infections by local application.

The attachment of encephalomyocarditis (EMC) virus to human nucleated cells susceptible to virus infection was examined with HeLa and K562 cell lines. Both cell types showed specific virus binding competitively blocked by unlabeled virions. The number of binding sites for EMC virus on HeLa and K562 cells were approximately 1.6 x 105 and 3.5 x 105 per cell, respectively, and dissociation binding constants were 1.1 and 2.7 nM, respectively. Treatment of cells with cycloheximide after pretreatment with trypsin eliminated EMC virus attachment, suggesting that the virus-binding moiety is proteinaceous in nature. Digestion of cells, cell

SUMMARYEncephalomyocarditis (EMC) and influenza viruses attach to human erythrocytes causing haemagglutination of the cells. Sialoglycoproteins, containing predominantly glycophorin A, from these cells behave as soluble virus receptors and inhibit haemagglutination by both viruses. Removal of 43% of the sialic acid from erythrocytes with neuraminidase prevented their haemagglutination by EMC virus while loss of 40% of glycophorin sialic acid destroyed its inhibitory properties against this virus. However, about 80% of the sialic acid had to be removed from erythrocytes or from glycophorin to achieve the same results for influenza virus. Trypsin treatment of erythrocytes or glycophorin had little effect on haemagglutination or inhibition involving either virus, although the glycopeptides released contain up to 70% of the total sialic acid, and despite the fact that glycophorin was drastically reduced in size as shown by SDS-polyacrylamide gel electrophoresis. It is concluded that not all of the sialic acid present in erythrocyte sialoglycoprotein receptors is involved in attachment of EMC or influenza viruses and that the attachment sites on erythrocytes for these viruses are not identical.