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Biomedical subjects

J L Gerin

Publications and source records attributed to J L Gerin.

At least 73 records · Page 4Linked to original sources
PubMed1991

Hepatocellular carcinoma in Richardson's ground squirrels (Spermophilus richardsonii): evidence for association with hepatitis B-like virus infection.

During studies of seasonal obesity, a high frequency of hepatic neoplasms was observed in Richardson's ground squirrels. Of 12 Richardson's ground squirrels examined thoroughly, 7 had mild or moderate degrees of chronic portal hepatitis and 6 (50%) had hepatocellular carcinoma. Serological tests for hepadnavirus surface antigen, anti-core antibody and virion DNA that recognize the ground squirrel hepatitis virus of California ground squirrels (Spermophilus beecheyi) were uniformly negative. Southern blot analyses of EcoRI digests of liver cell DNA demonstrated 3.2 kb fragments that hybridized with a ground squirrel hepatitis virus-specific probe in nontumorous liver tissue from 6 of 10 ground squirrels and in hepatocellular carcinoma specimens from 2 of 5 squirrels indicating infection with a hepadnavirus related to ground squirrel hepatitis virus. Failure, however, to detect serum antibody to ground squirrel hepatitis core antigen suggested probable antigenic differences between the ground squirrel hepatitis virus of California ground squirrels and the putative Richardson's ground squirrel agent. Further studies are required to fully characterize the hepadnavirus of Richardson's ground squirrels and to determine its relationship to hepatocarcinogenesis in this species.

Animals↗
PubMed1991

The novel tertiary structure in delta RNA may function as a ribozyme control element.

The viroid-like domain making up the lefthand end of the delta hepatitis genome (Branch et al., 1989) has structural elements whose interactions may be essential for replication. This portion of the genome is highly conserved in primary sequence and contains two well-defined types of structural features: sites capable of self-cleavage, and those forming a UV-sensitive element of local tertiary structure which is very stable and contains non-Watson:Crick bonds that may form a distinctive surface for binding specific proteins. The proximity of the tertiary structure to the genomic self-cleavage site suggests that the photoreactive element may regulate the ribozyme. This element's stability would limit "breathing" in this region of the circular genome, maintaining the ribozyme in the "off" conformation; its tight structure could be relieved by protein binding at the time of replication. We previously mapped a novel local tertiary structure to a highly conserved portion of the viroid genome (Branch et al., 1985). The many additional properties shared by viroids, related infectious circular RNAs of plants, and the delta agent are discussed in a recent article (Branch et al., in press-a).

Base Sequence↗
PubMed1990

Alpha-fetoprotein in the woodchuck model of hepadnavirus infection and disease: normal physiological patterns and responses to woodchuck hepatitis virus infection and hepatocellular carcinoma.

Persistent infection of the eastern woodchuck (Marmota monax) with the woodchuck hepatitis virus (WHV) produces disease sequelae similar to those observed in humans with persistent hepatitis B virus infection, including hepatocellular carcinoma (HCC). To further characterize serological markers of HCC in the woodchuck, serum alpha-fetoprotein (AFP) was measured under normal physiological conditions and following infection with WHV. Serum AFP was elevated in association with WHV-induced hepatitis and HCC and was a useful indicator of hepatic responses in individual animals throughout the course of experimental WHV infection. The frequent occurrence of normal elevations in serum AFP during the fall and winter, however, limits the use of AFP as a marker for early detection of HCC. The present temporal studies of AFP responses in WHV-infected woodchucks have identified several stages of infection where virological and cellular interactions can be investigated at the molecular level. Studies of AFP in the woodchuck model should provide opportunities to further elucidate the physiological and immunological functions of AFP and to understand virus-host cell interactions during the course of experimental hepadnavirus infection leading to HCC.

Aging↗
PubMed1990

Alpha-fetoprotein in the woodchuck model of hepadnavirus infection and disease: immunochemical analysis of woodchuck alpha-fetoprotein and measurement in serum by quantitative monoclonal radioimmunoassay.

Woodchuck hepatitis virus infection of the eastern woodchuck represents a useful model for the study of hepatitis B virus infection and disease in humans, including hepatocellular carcinoma. In man, hepatocellular carcinoma is frequently detected and monitored using assays for serum alpha-fetoprotein. To study the relationship between alpha-fetoprotein and woodchuck hepatitis virus-induced hepatocellular carcinoma in the woodchuck model, we produced a monoclonal antibody to woodchuck alpha-fetoprotein and used biophysical and immunochemical methods to demonstrate its specificity and affinity (7 x 10(8) L/mol) for woodchuck alpha-fetoprotein. A competition radioimmunoassay was then developed and standardized for measuring serum alpha-fetoprotein concentrations. In the radioimmunoassay system, woodchuck alpha-fetoprotein was detected between 20 ng/ml (20% to 25% inhibition) and 8,500 ng/ml (97% to 98% inhibition). Elevated serum alpha-fetoprotein concentrations (450 to 452,000 ng/ml) were measured in 21 of 23 woodchucks in the advanced stages of woodchuck hepatitis virus-induced hepatocellular carcinoma. Serum alpha-fetoprotein was elevated above normal (greater than or equal to 450 ng/ml) as early as 3 to 11 mo before terminal hepatocellular carcinoma in 11 of 16 of the woodchuck hepatitis virus-carrier woodchucks. In a pilot study, serum alpha-fetoprotein became markedly elevated above normal in woodchuck hepatitis virus-carrier woodchucks that developed hepatocellular carcinoma but not in serologically recovered or uninfected woodchucks (i.e., without hepatocellular carcinoma). Thus, alpha-fetoprotein may provide a useful noninvasive marker in the woodchuck model for detecting and monitoring woodchuck hepatitis virus-induced hepatocellular carcinoma from earlier stages.

Animals↗
PubMed1990

Riboprobe assay for HDV RNA: a sensitive method for the detection of the HDV genome in clinical serum samples.

We have used a new hybridization assay for the detection of the genome of hepatitis delta virus (HDV) in serum using a strand-specific RNA probe obtained by transcription of a recombinant riboprobe. This assay was tested on a panel of 30 sera from HBsAg carriers with hepatitis delta antigen (HDAg) in the liver. The riboprobe assay detected HDV RNA in the serum of 83% of the patients, while 63% were positive using the DNA hybridization assay. HDAg was detected in 73% of the same sera by immunoblotting. The riboprobe assay was also compared to other assays on serial samples from an experimentally infected chimpanzee. These results demonstrate that the Northern blot assay using the RNA probe is more sensitive than the homologous DNA probe for the detection of HDV in serum and is also more sensitive than the immunoblot assay for HDAg. The riboprobe assay is the most sensitive of currently available methods to measure HD viremia.

Adult↗
PubMed1990

Experimental WHV infection of woodchucks: an animal model of hepadnavirus-induced liver cancer.

Woodchuck hepatitis virus (WHV), a member of the Hepadnaviridae, is closely related to HBV in its virus structure, genetic organization and mechanism of replication. Natural infection of woodchucks is associated with chronic liver disease and primary hepatocellular carcinoma (HCC). A concerted effort to develop the woodchuck as an experimental animal model of hepadnavirus-induced disease was initiated in 1980. The experimental studies have established the following: (1) Chronic WHV carriage as an outcome of infection is a function of age of exposure, virus dose and, possibly, virus strain. As in humans, animals infected as newborns develop chronic antigenemia at high rates compared to young adults. (2) WHV causes primary hepatocellular carcinoma (HCC) in woodchucks. Hundred percent of experimentally-induced chronic WHsAg carriers developed HCC within three years; no HCC has occurred in concurrent uninfected control animals born and held in the same laboratory environment. The predictable course of experimental WHV infection leading to liver disease in woodchucks makes this an ideal model in which to study the natural history of hepadnavirus and to develop effective prophylactic and therapeutic strategies.

Animals↗
PubMed1990

Evidence against a requisite role for defective virus in the establishment of persistent hepadnavirus infections.

The factors involved in the establishment of persistent hepadnavirus infection are poorly understood. Recent findings demonstrate that the sequence of the genome of hepatitis B virus (HBV) is variable in infected individuals and that, in some cases, virus mutants predominate. Our objectives in the present study were to analyze the variability of woodchuck hepatitis virus (WHV) genomes in an infected animal and to determine whether sequence heterogeneity played a critical role in the ability of WHV to induce chronic infection. We cloned and determined the complete nucleotide sequence of three supercoiled genomes from an animal that became infected after inoculation with a standardized WHV serum pool (i.e., the WHV7 virus pool). We found that there were four nucleotide substitutions among the three genome sequences as well as a 73-nucleotide deletion in one of the recombinants. DNA transfection experiments revealed that only one of the three recombinants was capable of independent replication. These data suggest that a significant proportion of replicative templates in woodchucks that are infected with WHV are defective virus genomes. Next, we compared the outcome of acute infection after inoculation with a serum pool containing a uniform population of replication competent virus (i.e., the WHV7R pool) with a serum pool composed of WHV genomes of variable sequence. The WHV7R serum pool originated from a woodchuck that became a chronic carrier after in vivo transfection of the liver with the infectious WHV7 recombinant. Neonatal woodchucks were inoculated with 5 x 10(6) WHV genome equivalents of either the WHV7 pool or the WHV7R pool. All animals in the study became acutely infected with WHV. Of the animals infected with the WHV7 serum pool, 65% became chronic carriers, while 80% of the animals infected with the WHV7R serum pool developed chronic infection. Thus, infection of woodchucks with a serum pool containing defective virus resulted in a rate of chronic WHV infection that was similar to, or even lower than, a rate from a pool containing only wild-type virus. This suggests that the presence of defective virus in the inoculum is not a prerequisite for the establishment of persistent hepadnavirus infections.

Animals↗
PubMed1990

In vitro immune responses to hepatitis B surface antigens S and preS2 during acute infection by hepatitis B virus in humans.

This study evaluated the in vitro immune responses to different components of the hepatitis B surface antigen (HBsAg) over the course of acute hepatitis B virus (HBV) infection. Early in the convalescent phase of infection, while HBsAg was present in the serum, peripheral blood mononuclear cells (PBMCs) were stimulated with preS2 peptide or hepatitis B surface protein. Specific IgG directed to different components of HBsAg was produced without a polyclonal increase in total IgG production. Stimulation with preS2 peptide produced IgG to the preS2 peptide (anti-preS2) and to the S antigen (anti-HBs). Hepatitis B surface protein stimulation produced anti-HBs but not anti-preS2. After this initial reactive phase, the PBMCs did not produce specific antibody when stimulated with either component of HBsAg; this effect lasted greater than 1 year. At some time 1-2 years after acute infection, the pattern of in vitro S antigen- and preS2 antigen-stimulated anti-HBs response reemerged in the PBMCs. Reemergence of sustained preS2 peptide-stimulated anti-preS2 response was not observed.

Cells, Cultured↗
PubMed1990

Natural history of experimental woodchuck hepatitis virus infection: molecular virologic features of the pancreas, kidney, ovary, and testis.

The kinetic patterns of woodchuck hepatitis virus (WHV) infection were monitored in the pancreas, kidneys, ovaries, and testes. Groups of woodchucks experimentally infected with a standardized inoculum of WHV were sacrificed at different times over a 65-week period beginning in the preacute phase of viral infection and continuing to the period of serologic recovery or the establishment of chronic infections and subsequent hepatocellular carcinoma (B. E. Korba, P. J. Cote, F. V. Wells, B. Baldwin, H. Popper, R. H. Purcell, B. C. Tennant, and J. L. Gerin, J. Virol. 63:1360-1370, 1989). Tissues from an additional group of long-term (2 to 3 years) chronic WHV carriers which had been infected with the same WHV inocula were also examined. Viral DNA replication intermediates were found in all four tissues during the acute phase of WHV infection. However, WHV DNA replication intermediates were observed only in the kidneys of a small proportion of the chronically infected animals. Following the acute phase of infection, WHV DNA was present only in the pancreas, kidneys, and ovaries of the chronically infected woodchucks. A progressive evolution of different WHV genomic forms related to the replicative state of WHV was observed in these tissues. Histologic evaluation of these four tissues revealed only minimal, localized lesions which were not correlated with the state of WHV activity. The observations compiled in this study further extend the tissue tropism of WHV.

Animals↗
PubMed1989

Hepatitis delta antigen. Antigenic structure and humoral immune response.

Hepatitis delta virus (HDV) is a small RNA virus that is dependent on helper functions provided by hepatitis B virus. The hepatitis delta Ag (HDAg) is the only protein known to be made from the viral genome, from an ORF with a coding capacity of 214 amino acids. The immunogenic epitopes of HDAg and the immune response to it were mapped by the use of synthetic peptides, antipeptide antibodies, and human mAb. Antipeptide sera covering approximately 60% of the linear sequence reacted with liver-derived HDAg. Antisera from HDV-infected humans, chimpanzees, and woodchucks reacted with from 2 to 13 of 15 peptides. The epitopes of two human anti-HD mAb were mapped to overlapping but distinct epitopes in the region around residues 106-123. Sera from infected humans, chimpanzees, and woodchucks were also tested by competition with the mAb. Use of the peptides and antipeptide sera defined one region in the sequence (residues 52-93) which is immunodominant in the immune response to HDAg. Reactivity of both peptides and antipeptide antibodies was very broad, covering most or all of the linear sequence. Competition assays also provided information on conformational epitopes, as well as the sequential epitopes defined by direct assays. The peptides and antipeptide antibodies should be useful in new assay development, in dissecting the anti-HD response in terms of chronic vs self-limited infection, and in studying the role of anti-HD in infection and recovery.

Amino Acid Sequence↗