Hepatitis C virus replication kinetics in chimpanzees with self-limited and chronic infections.

The availability of molecular beacon-based, real time polymerase chain reaction (PCR) and a semi-automated sample extraction procedure have made it possible for us to retrospectively examine HCV replication kinetics in HCV naive chimpanzees infected during the past 20 years. We compared these in 17 animals that developed chronic infection, and in 21 that developed self-limited infection. No differences were found in infecting dose, or replication kinetics in the acute phase between these two types of infection. An unanticipated finding was the fact that 10 of 17 animals developing chronic infection partially controlled virus replication for 48 +/- 48 weeks after typical acute phase viraemia, and prior to development of chronic infection. Twenty-nine out of 30 (29/30) sera, which were negative by quantitative PCR during the downregulated period, were, however, positive by the more sensitive Genprobe isothermal transcription-mediated amplification (TMA) assay. Thus, downregulation was not complete. Ten animals showing self-limited infection showed complete resolution of viraemia by TMA assay. Quasispecies analysis revealed that in all, except one case, the virus reappearing after downregulation was essentially identical to that of the originally infecting virus.

Characterization of the immune response against hepatitis C infection in recovered, and chronically infected chimpanzees.

The immune response to hepatitis C virus (HCV) is believed to be critical in determining the outcome of the disease. In this study we have analysed epitope recognition, cytokine profile, and anti-HCV antibody responses in chronically HCV-infected and recovered chimpanzees. Quantitative measurement of anti-HCV antibody in HCV-infected chimpanzees revealed that the response in HCV- recovered chimpanzees peaked within 4-20 weeks. In contrast, the anti-HCV antibody responses in chronically HCV infected chimpanzees did not peak until 100-200 weeks after infection, and decreased gradually thereafter. T cell proliferation assays measuring responses to pooled HCV proteins revealed significant increases in the 3H-uptake during the early stages of infection in recovered chimpanzees in comparison to the chronically infected ones. Class I-restricted epitopes of the core, and NS3 proteins of HCV were analysed using 9-10 mer overlapping peptides covering the core and NS3 proteins, and IFN-gamma ELISPOT technique. Our data indicated early and broad class-I restricted core, and NS3 protein epitope recognitions in HCV-recovered chimpanzees but not in chimpanzees that had been chronically infected. Additionally, dominant epitopes recognized early in infection (8 weeks) were no longer recognized later in infection (followed up to 64 weeks). Cytokines profiling revealed a 50-fold increase in TNF-alpha secretion in the supernatant of core-specific CD8 memory cells of the chronically infected chimpanzees in comparison to the recovered ones. In summary, multiple parameters correlate with HCV recovery in chimpanzees.

Perspectives on hepatitis B studies with chimpanzees.

Chimpanzees have been shown to be exquisitely susceptible to human hepatitis viruses, without themselves developing clinical illness, thus providing an important model for studies on these agents. Chimpanzees have contributed substantially to human welfare by making possible the development of hepatitis B vaccines, which now prevent development of cirrhosis and hepatocellular carcinoma in millions of people. They have provided a means to evaluate the efficacy of virus inactivation strategies, which have made blood derivatives formerly contaminated with blood-borne viruses (hepatitis B, C, and human immunodeficiency viruses) safe with respect to their transmission. In exchange for these contributions, humans owe chimpanzees lifelong retirement in sanctuaries that offer socialization and environmental enrichment.

Infectivity of blood from PCR-positive, HBsAg-negative, anti-HBs-positive cases of resolved hepatitis B infection.

BACKGROUND: Numerous reports have noted the existence of sera, particularly from resolving cases of HBV infection, that are positive for HBV DNA by PCR, despite being negative for HBsAg and IgM anti-HBc. If such blood is infective and detectable by HBV NAT screening, it seems desirable to introduce such screening for transfused blood. STUDY DESIGN AND METHODS: Three chimpanzees were inoculated with serum and lymphocytes from three patients who were HBV DNA PCR positive, but HBsAg negative. The animals were tested over a period of 15 months for HBsAg, anti-HBs, anti-HBc, and HBV DNA by PCR. RESULTS: All animals remained uninfected. CONCLUSION: Small amounts of plasma and MNCs from HBV DNA-positive HBsAg-negative blood do not appear to be infectious; however, further studies with larger volumes of inoculum should be conducted.

DNA prime/canarypox boost-based immunotherapy of chronic hepatitis B virus infection in a chimpanzee.

There are about 200 million chronic hepatitis B virus (HBV) carriers at high risk of development of cirrhosis and hepatocellular carcinoma. Termination of the carrier state may avert these risks. We have investigated immunotherapy for chronic HBV infection in a chimpanzee HBV carrier using recombinant DNA-based immunization followed by a recombinant canarypox booster. One week after the booster, HBV DNA declined greater than 400-fold and remained undetectable by the quantitative polymerase chain reaction (PCR) assay for 186 weeks. Plasma levels of hepatitis B surface antigen (HBsAg) declined for only a short time. The decline in HBV DNA correlated with a boost in gamma interferon production without a corresponding boost in cytotoxic T lymphocyte levels, and decline in the transcriptional template or covalently closed circular DNA level. Confirmation of these findings requires further studies in chimpanzees and/or in humans.

Examining the existence of the underwriting cycle in managed care organizations.

This article examines the existence of the underwriting or profitability cycle in the health insurance industry. Researchers have reported that a six-year cycle exists for health care insurers. That is, three years of profits then are followed by three years of losses. This article suggests that insurers react more quickly to losses and adjust their cost structures almost immediately. Health insurers react to both expected changes and current increases in the payoff ratio.

Full-genome sequence analyses of hepatitis B virus (HBV) strains recovered from chimpanzees infected in the wild: implications for an origin of HBV.

Hepatitis B virus (HBV) belongs to the genus Orthohepadnavirus of the family Hepadnaviridae. Having been found in various animals (duck, heron, woodchuck, ground squirrel, and primates), hepadnaviruses must have undergone a long history of evolution and may comprise more members than currently recognized. Chimpanzees may also have their own hepadnavirus, even if it might be very close to HBV. We analyzed HBV-like sequences from three chimpanzees (Pan troglodytes) that were most likely infected during their life in Africa in the wild. Two chimpanzees (Ch256 and Ch258) possessed a viral genome of 3182 nt in length with a 33-nt deletion in the preS1 region, which could not be classified into any of the six genotypes (A-F) of human HBV but was very homologous to a previously reported isolate from a London Zoo chimpanzee. Phylogenetically distinct from the HBV-like sequences from gibbons, orangutans, and a gorilla so far reported, the Ch256 and Ch258 isolates would represent an indigenous chimpanzee HBV (tentatively ChHBV). A third chimpanzee (Ch195) had a 3212-nt genome, classifiable into the genotype E of HBV. Because HBV-E has been found mostly in Africans, Ch195 may have been infected from a human source in Africa. However, an inverse scenario is also possible: a spread of HBV-E might have occurred from chimpanzees to humans a long time ago in Africa. Analysis of the arginine-rich C-terminal region of the core protein, which is well conserved among mammalian hepadnaviruses, indicated that HBV-E/F and nonhuman primate hepadnaviruses are much closer than HBV-A/B/C/D to the hepadnaviruses of woodchuck and ground squirrel. Our results support an "ex-nonhuman primate" hypothesis for the origin of HBV.

The price of pharmaceuticals given managed care health insurance membership.

The results indicate that managed care membership has impacted price trends for pharmaceuticals significantly. There are also implications for changing the status of drugs from prescription only to over-the-counter status.

Methodology Used in DNA-Based Prophylactic and Therapeutic Immunization Against Hepatitis B Virus in Chimpanzees.

Chimpanzees, because of their near-human nature, have special needs that must be met by those who carry out medical research with them. Perhaps the most important of these is the need for companionship. Chimpanzees kept alone become obviously depressed, and manifest stereotypic behavior such as compulsive rocking. We have followed a policy of keeping chimpanzees in groups of two or more, whenever possible. This has virtually prevented overt depressive symptomatology. This policy has not significantly affected studies on hepatitis B and C (1).

Significance of the anti-E2 response in self-limited and chronic hepatitis C virus infections in chimpanzees and in humans.

To determine whether there was a correlation between the kinetics or frequency of antibody to mammalian-derived hepatitis C virus (HCV) second envelope protein (E2) and development of chronicity or self-limitation of HCV infections, serial sera were examined for anti-E2, anti-HCV with confirmation with Matrix 2.0 (Abbott Laboratories, Abbott Park, IL), and reverse transcriptase-polymerase chain reaction (RT-PCR) from 6 cases of self-limited infection and 6 cases of chronic infection in chimpanzees, and from 5 cases of self-limited infection and 3 cases of chronic infection in patients. Anti-E2 developed earlier, more frequently, and to higher titer in chimpanzees and patients who were developing chronic infection than in those with self-limited infections. Thus anti-E2 is unlikely to play a role in self-limitation of the infection. However, long-term persistence of anti-E2 correlates with chronic infection. There was little or no correlation between the timing of development of anti-E2 and anti-HCV.

Hepatitis C virus-specific CTL responses in PBMC from chimpanzees with chronic hepatitis C: determination of CTL and CTL precursor frequencies using a recombinant canarypox virus (ALVAC).

The aim of this study was to evaluate HCV-cytotoxic T lymphocyte response from PBMC in bulk CTL assays and in CTL precursor analyses using in vitro stimulation with canarypox virus (ALVAC) expressing HCV-capsid/E1/E2/NS2/NS3 antigens. Canarypox virus is naturally host-range restricted and does not replicate or cause cytopathology on mammalian cells. PBMC were obtained from four chimpanzees with chronic hepatitis C infection and one uninfected chimpanzee. CTL from bulk culture of PBMC and CTL precursor frequencies were found in three of the four chronically infected chimpanzees using ALVAC in vitro stimulation. No CTL response was detected in PBMC from the uninfected chimpanzee. The precursor frequencies of CTL specific for capsid, NS2 and NS3 proteins ranged between 1/2663 and 1/27202. No correlation was observed between percent cytolysis in bulk culture and CTL precursor frequencies. This method may prove useful in assessing the correlation between HCV-CTL response and virological or histological status.

Client flow through the Women, Infants, and Children Public Health Program.

The Women, Infants, and Children (WIC) Program, managed by the county boards of health, provides nutrition, limited physical examinations, and food vouchers for pregnant women and for children with nutritional deficiencies. Because federal guidelines for the WIC program leave little maneuvering room to improve the delivery of services, we analyzed the client flow through a WIC clinic in the Atlanta metropolitan area to determine how that flow could be managed more efficiently. The challenge facing the WIC clinic was to increase the efficiency of their operation in an environment characterized by resource constraints, rigid regulations, and dysfunctional client behavior. In a limited physical space, the WIC clinic was expected to provide a number of sequential services to a client population that failed to arrive or arrived late 40 percent-50 percent of the time. The provision of services was further complicated by walk-ins, which were not only common but, according to federal guidelines, also must be accommodated. To analyze the clinic's problem, we used the General Purpose Simulation System for personal computer (GPSS/PC) to simulate client flow through the clinic. Estimates of the average amount of time a client spent in the clinic as well as average waiting times at each station and clerk and nurse utilization rates were generated assuming a variety of staffing levels. For comparison purposes, each version of the model was run with a 20-minute time lag before a late appointment was filled, and then a one-minute lag. The data used for the simulation were collected by clinic personnel during February 1994. It included the number of clerks and nurses available; the waiting time to see clerks and nurses for walk-ins and appointments; the waiting time to get WIC vouchers; the number of appointments met; the number of appointments missed; and the total time in the clinic for walk-ins and appointments. In all three versions of the model that were estimated, the results of the simulations revealed that reducing the time before a late appointment was filled significantly decreased the time spent in the clinic, on average, for all clients. Furthermore, the time spent waiting for both clerks and nurses decreased, the utilization of the clerks decreased, and the utilization of the nurses increased in two of the three estimations.

Immunity in chimpanzees chronically infected with hepatitis C virus: role of minor quasispecies in reinfection.

We have previously reported that chimpanzees chronically infected with hepatitis C virus (HCV) could be reinfected, even with the original infecting strain. In this study we tested the hypothesis that this might reflect the presence of minor quasispecies to which there was little or no immunity. To evaluate this hypothesis, we sequenced multiple clones taken at intervals after primary infection and rechallenge from four chronically infected chimpanzees. The inoculum used in these studies (HCV-H, genotype 1a) revealed 17 separate variants among 46 clones sequenced. Following challenge, each of the four challenged animals showed marked alterations of their quasispecies distribution. The new variants, which appeared 1 to 6 weeks after challenge, were either identical to or closely resembled variants present in the challenge inoculum. These results, paralleled by an increase in viremia in some of the challenged animals, suggest that quasispecies in the challenge inoculum were responsible for signs of reinfection and that there was little immunity. However, the newly emerged quasispecies completely took over infection in only one animal. In the remaining three chimpanzees the prechallenge quasispecies were able to persist. The natural evolution of infection within chimpanzees resulted in variants able to compete with the inoculum variants. Whether through reexposure or the natural progression of infection, newly emerged quasispecies are likely to play a role in the pathogenesis of chronic HCV infection.

Successful nucleic acid based immunization of newborn chimpanzees against hepatitis B virus.

To determine whether DNA based immunization could protect newborn chimpanzees against a challenge infection with hepatitis B virus, two chimpanzees were immunized on the day of birth with a plasmid coding for hepatitis B surface antigen, and boosted at 6 and 24 weeks. Both animals produced transient antibody to the hepatitis B surface antigen. Following challenge with hepatitis B virus at 33 weeks the two immunized animals developed anamnestic antibody responses, however, neither developed detectable hepatitis B surface antigen or antibody to the core protein, the conventional markers of hepatitis B infection. Both of these markers appeared in an unimmunized control animal. We conclude that DNA based immunization can induce protective immunity in newborn chimpanzees.

Cloning of a cysteine protease required for the molting of Onchocerca volvulus third stage larvae.

We have investigated the involvement of a cysteine protease in the development of Onchocerca volvulus fourth stage larvae (L4) by testing the effect of cysteine protease inhibitors on the survival of third stage larvae (L3), and the molting of L3 to L4 in vitro. When larvae were cultured in the presence of specific inhibitors, the peptidyl monofluoromethylketones, viability of either L3 or L4 was not affected. However, the inhibitors reduced the number of L3 that molted to L4 in vitro in a time- and dose-dependent manner. Molting was completely inhibited in the presence of 50-250 microM inhibitor. Ultrastructural examination of L3 that did not molt in the presence of inhibitors indicated that new L4 cuticle was synthesized, but there was no separation between the L3 and the L4 cuticles. The endogenous cysteine protease was detected in molting larvae after binding to labeled inhibitors, and by antibodies directed against a recombinant O. volvulus L3 cysteine protease that was cloned and expressed. The enzyme was detected in cuticle regions where the separation between the cuticles occurs in molting larvae. These studies suggest that molting and successful development of L4 depends on the expression and release of a cysteine protease.

Immune response to epitopes of hepatitis C virus (HCV) structural proteins in HCV-infected humans and chimpanzees.

Hepatitis C virus (HCV)-infected humans and chimpanzees were studied for reactivity with linear epitopes in HCV H strain structural proteins. In 10 HCV-infected patients, epitopes were mostly mapped to the capsid and E1 proteins but not to E2. However, serum from 1 HCV-infected blood donor with a high anti-capsid titer reacted with multiple epitopes including E2. By contrast, antibody to capsid epitopes was seen in sera from HCV-rechallenged chimpanzees but not from chronically infected animals. No reactivity was observed to GOR epitope in chimpanzees, while 6 of 11 human subjects reacted with this host-coded antigen. Reactivity to rare epitopes in E2 was seen in chimpanzees with chronic and self-limited infections. Reactivity to one peptide of E1 (aa 316-329) was observed in 10 of 11 sera from HCV-infected humans and 11 of 15 chimpanzee sera. However, reactivity to this epitope was also seen in normal chimpanzees and in 6 (7.1%) of 84 uninfected human subjects.

Transglutaminase-catalyzed reaction is important for molting of Onchocerca volvulus third-stage larvae.

Highly insoluble proteins, which are probably cross-linked, are common in the cuticle and epicuticle of filarial parasites and other nematode species. We have investigated the possible involvement of transglutaminase (TGase)-catalyzed reactions in the development of Onchocerca volvulus fourth-stage larvae (L4) by testing the effects of TGase inhibitors on the survival of third-stage larvae (L3) and the molting of L3 to L4 in vitro. The larvae were cultured in the presence of three specific TGase inhibitors: monodansylcadaverine, cystamine, and N-benzyloxycarbonyl-D,L-beta-(3-bromo-4,5-dihydroisoxazol-5-yl)-al anine benzylamide. None of the inhibitors reduced the viability of either L3 or L4. However, the inhibitors reduced, in a time- and dose-dependent manner, the number of L3 that molted to L4 in vitro. Molting was completely inhibited in the presence of 100 to 200 microM inhibitors. Ultrastructural examination of L3 that did not molt in the presence of monodansylcadaverine or cystamine indicated that the new L4 cuticle was synthesized, but there was an incomplete separation between the L3 cuticle and the L4 epicuticle. The product of the TGase-catalyzed reaction was localized in molting L3 to cuticle regions where the separation between the old and new cuticles occurs and in the amphids of L3 by a monoclonal antibody that reacts specifically with the isopeptide epsilon-(gamma-glutamyl)lysine. These studies suggest that molting and successful development of L4 also depends on TGase-catalyzed reactions.

Hospital indigent care expenditures.

The Georgia State Health Planning Agency provided financial information for 144 general hospitals for the year 1992. Not-for-profit hospitals do not appear to fund charity care to a greater degree than for-profit hospitals. Uninsured patients in Georgia do not appear to use emergency department services instead of a primary care physician. Patient behavior may be influenced by the fact that many public health departments offer free primary care.