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Biomedical subjects

R H Purcell

Publications and source records attributed to R H Purcell.

At least 235 records · Page 13Linked to original sources
PubMed1986

Fecal excretion of Greek strains of hepatitis A virus in patients with hepatitis A and in experimentally infected chimpanzees.

The presence of hepatitis A virus (HAV) in stool samples was determined in 36 children (mean age, 8.9 years) and 38 adults (mean age, 19.9 years) with acute type A hepatitis. Three stool samples, taken on admission and thereafter at three-to-five-day intervals, were collected from each patient. The first day of dark urine was considered to be the onset of illness. Molecular hybridization of cloned HAV cDNA to fecal extracts was used to detect HAV RNA; radioimmunoassay was used to detect HAV antigen. In all of the samples tested, HAV RNA was detected significantly more frequently than HAV antigen (28.4% vs. 8.1%, P less than .001). HAV RNA was detected with equal frequency in both children and adults during the first week of illness. However, HAV RNA was detected more frequently in children than in adults during the second week of illness (45.7% vs. 18.9%, P less than .05). Among patients with HAV RNA, detection in multiple samples was more frequent in children than in adults (38.9% vs. 7.9%, P less than .01), especially among males.

Adolescent↗
PubMed1986

Significance of IgM antibody to hepatitis B core antigen in a Greek population with chronic hepatitis B virus infection.

IgM antibody to hepatitis B core antigen (IgM anti-HBc) may indicate an active immune response to persistent infection with hepatitis B virus (HBV). We studied 186 Greek HBsAg carriers for IgM anti-HBc and attempted to correlate it with other HBV and hepatitis delta virus (HDV) markers. Overall, IgM anti-HBc was detected more frequently than HBV DNA in this population (50% vs 34, p less than 0.001); this was also true for the 149 of the 186 HBsAg carriers with antibody to hepatitis B e antigen (anti-HBe) (48% vs 22%, p less than 0.001). The opposite was found in the carriers positive for hepatitis B e antigen (HBeAg): HBV DNA was observed in 93% and IgM anti-HBc in 64% of the cases (p less than 0.05). The detection of these markers was independent of sex. Serum alanine aminotransferase (ALT) levels were significantly more elevated in patients with positive tests for IgM anti-HBc and HBV DNA than in patients positive only for HBV DNA (p less than 0.001) irrespective of their HBeAg or anti-HBe status. Moreover, the detection of elevated ALT was independent of the intensity of the HBV DNA hybridization signal. Antibodies to hepatitis delta antigen (HDAg) were only found in 4 (2.4%) of 167 patients tested.

Adult↗
PubMed1986

Hepadnavirus infection of peripheral blood lymphocytes in vivo: woodchuck and chimpanzee models of viral hepatitis.

The peripheral blood lymphocytes (PBL) of five hepatitis B virus (HBV)-infected chimpanzees and 17 woodchuck hepatitis virus (WHV)-infected woodchucks were examined for the presence of viral DNA and RNA. HBV DNA was detected in the PBL of three of three chronically infected chimpanzees but in neither of two animals with acute HBV infection. WHV DNA was found in the PBL of 11 of 13 chronically infected woodchucks and in the PBL and bone marrow of 1 of 4 woodchucks with antibody to WHV surface antigen. Viral DNA in the PBL and bone marrow was episomal, primarily existing as multimers with some monomeric forms. Integrated HBV DNA was detected in the PBL of one chronically infected chimpanzee, but only for a brief period. Viral RNA was also detected in the PBL, although less frequently than was DNA. HBV RNA in chimpanzee PBL existed as 3.8- and 7.5-kilobase species, while 2.3- and 3.8-kilobase WHV RNA was found in woodchuck PBL. Subfractionation of PBL isolated from the chronically infected chimpanzees demonstrated that HBV DNA and RNA were located in B and T cells. No HBV DNA was detected in the macrophages. These results, along with the recent reports of HBV nucleic acids in the PBL of human patients, suggest that infection of PBL may be a general phenomenon associated with the pathology of hepadnaviruses.

Animals↗
PubMed1986

Detection of a genome-linked protein (VPg) of hepatitis A virus and its comparison with other picornaviral VPgs.

The nucleotide sequence corresponding to the P3 region of the hepatitis A virus (HAV) polyprotein genome was determined from cloned cDNA and translated into an amino acid sequence. Comparison of the amino acid sequences of the genome-linked proteins (VPgs) of other picornaviruses with the predicted amino acid sequence of HAV was used to locate the primary structure of a putative VPg within the genome of HAV. The sequence of HAV VPg, like those of other picornaviral VPg molecules, contains a tyrosine residue as a potential binding site for HAV RNA in position 3 from its N terminus. The potential cleavage sites to generate VPg from a putative HAV polyprotein are between glutamic acid and glycine at the N terminus and glutamic acid and serine or glutamine and serine at the C terminus. A synthetic peptide corresponding to 10 amino acids of the predicted C terminus of HAV VPg induced anti-peptide antibodies in rabbits when it was conjugated to thyroglobulin as a carrier. These antibodies were specific for the peptide and precipitated VPg, linked to HAV RNA, from purified HAV and from lysates of HAV-infected cells. The precipitation reaction was blocked by the synthetic peptide (free in solution or coupled to carrier proteins) and prevented by pretreatment of VPg RNA with protease. Thus, our predicted amino acid sequence is colinear with the nucleotide sequence of the VPg gene in the HAV genome. From our results we concluded that HAV has the typical organization of picornavirus genes in this part of its genome. Similarity among hydrophobicity patterns of amino acid sequences of different picornaviral VPgs was revealed in hydropathy plots. Thus, the VPg of HAV appears to be closely related to VPg1 and VPg2 of foot-and-mouth disease virus. In contrast, HAV VPg has a unique isoelectric point (pI = 7.15) among the picornavirus VPgs.

Amino Acid Sequence↗
PubMed1986

Protection of chimpanzees from type B hepatitis by immunization with woodchuck hepatitis virus surface antigen.

Two chimpanzees immunized with woodchuck hepatitis virus (WHV) surface antigen (WHsAg) developed antibodies cross-reactive with hepatitis B virus (HBV) surface antigen (HBsAg). After challenge with HBV, one animal was completely protected and the other experienced a subclinical infection, without evidence of liver disease. Three woodchucks immunized with HBsAg developed antibodies to HBsAg which did not cross-react with WHsAg. After challenge with WHV, all three woodchucks developed typical acute infections with associated hepatic lesions. Serological studies with the cross-reactive antibodies raised in chimpanzees suggested that the protective epitopes of WHsAg were related to the group a specificity of HBsAg. These studies indicated that cross-protective epitopes are shared by HBV and WHV; however, the humoral response to these epitopes can vary among species.

Animals↗
PubMed1986

Failure to detect polyalbumin-binding sites on the woodchuck hepatitis virus surface antigen: implications for the pathogenesis of hepatitis B virus in humans.

Binding sites for polymerized albumin on hepatitis B virus components were reported in human hepatitis B virus chronic carriers predominantly with active viral replication (HB e antigen positive). The presence of comparable albumin-binding sites in the woodchuck hepatitis virus (WHV) model was examined on WHV components obtained from woodchucks with active viral replication (DNA polymerase positive). Binding sites for polymerized woodchuck serum albumin were not detected on the intact WHV virion, on 22-nm woodchuck hepatitis surface antigen (WHsAg), or on WHsAg polypeptides. Woodchuck albumin was not detected in purified 22-nm WHsAg, and anti-albumin antibodies were not detected in WHV chronic-carrier woodchucks. Our results in the WHV model argue against a role for viral polyalbumin-binding sites in tissue- and host-specific virus infectivity.

Animals↗
PubMed1986

Antibody to hepatitis B core antigen as a paradoxical marker for non-A, non-B hepatitis agents in donated blood.

The relationship between the presence of antibody to hepatitis B core antigen (anti-HBc) in donor blood and the development of hepatitis in recipients of that blood was studied in 6293 blood donors and 481 recipients who were followed for 6 to 9 months after transfusion. Of 193 recipients of at least 1 unit of blood positive for anti-HBc, 23 (11.9%) developed non-A, non-B hepatitis compared with 12 (4.2%) of 288 recipients of only anti-HBc-negative blood (p less than 0.001). Donor anti-HBc status was not significantly associated with the development of hepatitis B in the recipient and was negatively associated with the development of cytomegalovirus hepatitis. The relationship of donor anti-HBc status and the development of non-A, non-B hepatitis in the recipient was independent of transfusion volume and elevated donor transaminase level. Although 88% of anti-HBc-positive blood units were not associated with recipient non-A, non-B hepatitis, calculation of maximal corrected efficacy predicted that exclusion of anti-HBc-positive donors might have prevented 43% of the cases of non-A, non-B hepatitis with a donor loss of 4%. Because of the serious chronic consequences of non-A, non-B hepatitis, surrogate tests for non-A, non-B virus carriers must be seriously considered.

Alanine Transaminase↗
PubMed1986

Serologic markers of hepatitis B virus (HBV) and hepatitis D virus infection in carriers of hepatitis B surface antigen who are frequently exposed to HBV.

Serum hepatitis B e antigen (HBeAg) and HBV DNA are indicators of active replication of HBV, whereas IgM antibody to hepatitis B core antigen (IgM anti-HBc) may indicate an active immune response to chronic HBV infection. Fifty-eight carriers of hepatitis B surface antigen (HBsAg) who had frequent parenteral exposures were studied for the presence of HBeAg, HBV DNA, IgM anti-HBc and hepatitis delta virus (HDV) serologic markers. Active replication of HBV was detected in 36.2% (25% of drug addicts, 16.7% of thalassemia patients, and 46.9% of hemodialysis patients) and seropositivity for IgM anti-HBc in 55.2% of the HBsAg carriers. Among the 39 HBsAg carriers who were negative for HBeAg, IgM anti-HBc was detected significantly more frequently than HBV DNA (46.1% vs. 5.1%, p less than 0.001). Serologic evidence of HDV infection was detected in 35% of drug addicts, 50% of thalassemia patients and in 9.4% of hemodialysis patients. These data revealed that continued replication of HBV was more frequent in hemodialysis patients than in drug addicts and thalassemia patients who are HBsAg carriers and the opposite was true for the prevalence of HDV infection.

Adolescent↗
PubMed1985

A final report on safety and immunogenicity of a bivalent aqueous subunit HBV vaccine.

The bivalent form of an aqueous formalin-inactivated hepatitis B vaccine was evaluated for safety and immunogenicity in chimpanzees. To evaluate safety five animals were inoculated intravenously with vaccine containing 500 micrograms HBsAg and two animals with 50 micrograms. None of these animals developed hepatitis or any serologic marker indicative of the presence of residual live virus in the vaccine. Twenty-four animals were used to evaluate immunogenicity and protective efficacy. Seven of these immunized animals produced weak or no anti-HBs responses. Two doses of 50 micrograms HBsAg given subcutaneously 1 month apart protected each of four animals that were challenged with 10(3.5) CID50 HBV at 6 and 12 months after immunization and protected three of four animals challenged at 24 months against development of hepatitis or HBsAg. Three of 4 animals in each group immunized with two doses of 20, 10, or 5 micrograms HBsAg were similarly protected when challenged 6 months after immunization. Thirteen of 20 immunized animals that did not develop HBsAg after challenge with HBV developed anamnestic anti-HBs or anti-HBc responses between 2 and 18 months after challenge, indicating minimal replication of challenge virus. The time of onset and frequency of occurrence of these delayed responses was related to the titer of anti-HBs at the time of challenge. False positive Ausab test results were observed in quarantined chimpanzees. These were neither preceded by appearance of HBsAg nor accompanied by development of anti-HBc. In most cases these reactions were due to a reactant having a sedimentation coefficient and an electrophoretic mobility resembling that of IgM. This reactant generally did not appear to confer resistance to challenge with HBV. The humoral immune response was characterized as being entirely of the IgM class 2 weeks after immunization and switched entirely into the IgG class by 10-12 weeks after vaccine administration. At the time of challenge all animals with antibody had anti-HBs of subtype a.

Animals↗
PubMed1985

Frequency and significance of delta antibody in acute and chronic hepatitis B. A United States experience.

Of 560 hepatitis B surface antigen-positive patients who were tested for antibody to hepatitis delta-antigen by blocking radioimmunoassay, 29 (5%) were seropositive. Patients with chronic active hepatitis had a greater frequency of seropositivity than those with chronic persistent hepatitis (26% vs. 0%, p less than 0.05), and patients with symptomatic chronic disease harbored the antibody more commonly than asymptomatic counterparts (14% vs. 2%, p less than 0.01) or patients with acute hepatitis (14% vs. 1%, p less than 0.02). Of 8 patients with acute fulminant hepatitis, including 6 who died of liver failure, none were seropositive. Antibody was detected in drug users, dialysis patients, hemophiliacs, and transfusion recipients; in 17 patients, however, including 3 homosexuals, it occurred sporadically. Samples harvested in 1969 contained delta-antibody. Antibody was found in most ethnic groups, including Orientals, where it occurred only in relocated Vietnamese. We conclude that delta-antibody is detected infrequently in a diverse referral population within the United States. Seropositivity is associated with symptomatic chronic disease and histologic findings of chronic active hepatitis. Homosexuals and resettled Vietnamese are susceptible to sporadic delta-infection.

Acute Disease↗
PubMed1985

Radioimmunoassay and characterization of woodchuck hepatitis virus core antigen and antibody.

Solid-phase radioimmunoassays for woodchuck hepatitis virus core antigen (WHcAg) and antibody (anti-WHc) were developed. WHcAg in woodchuck liver homogenates was characterized by ultracentrifugation in CsCl gradients; both heavy (1.35 g/cm3) and light (1.31 g/cm3) cores were obtained from the liver of an animal during acute WHV infection, which is consistent with observations in hepatitis B virus infection in man. Endpoint titers of anti-WHc were higher in chronic WHV carriers than in animals recovered from acute infections. Both IgM and IgG anti-WHc antibodies were produced by infected woodchucks. A survey of colony woodchucks demonstrated that 88/89 animals having one or more markers of past or ongoing WHV infection were positive for anti-WHc. Thus, serum anti-WHc appears to be a sensitive marker of WHV infection.

Animals↗
PubMed1985

Sequence analysis of hepatitis A virus cDNA coding for capsid proteins and RNA polymerase.

We report here the nucleotide sequence corresponding to two large regions of the hepatitis A virus (HAV) genome. These comprise a sequence of 3274 bases corresponding to the 5' end of the genome, which includes the putative capsid protein region of this picornavirus, and 1590 bases corresponding to the 3' end of the genome, terminating in a 15-base poly(A) tract. These sequences revealed that HAV had the characteristic genomic organization of picornaviruses: an open reading frame beginning approximately 750 bases from the 5' end of the RNA and a termination codon 60 bases from the 3' poly(A) tract. The predicted amino acid sequences of both regions have been compared to analogous regions previously determined for other picornaviruses. There was sufficient homology to conclude that the 5' region of HAV codes for capsid proteins and that the 3' region codes for an RNA polymerase. However, these regions of HAV were not found to be closely related to analogous regions of poliovirus, encephalomyocarditis virus, and foot and mouth disease virus.

Amino Acid Sequence↗
PubMed1985

Double infections with hepatitis A and B viruses.

Ten (2.8%) asymptomatic carriers of HBsAg and four (1.1%) patients with acute hepatitis B virus (HBV) infection were detected among 356 adults with acute viral hepatitis A (HAV) consecutively admitted to the Athens Hospital for Infectious Diseases from May 1981 to March 1984. These patients did not differ in clinical, epidemiologic (except in age), biochemical or serologic characteristics from patients acutely infected with HAV alone. Transient suppression of the HBV replication and disappearance of the HBV DNA accompanied by seroconversion from HBeAg positive to anti-HBe positive were detected in one and two carriers respectively. The titer of non-class-specific anti-HBc was low (less than or equal to 10(-2)) in all cases. These data suggest that superinfection of HBsAg carriers with HAV does not cause more severe disease or influence adversely the course of chronic hepatitis B disease. However, accurate diagnosis of double infections is necessary for prognosis of the liver disease and appropriate management of the patient's environment. This is quite important in areas with a high prevalence of HBV infections, like Greece, where double infections are relatively common.

Acute Disease↗