Clinical studies previously demonstrated that live influenza A virus vaccines derived by genetic reassortment from the mating of influenza A/Ann Arbor/6/60 (H2N2) cold-adapted (ca) donor virus with epidemic wild-type influenza A viruses are reproducibly safe, infectious, immunogenic, and efficacious in the prevention of illness caused by challenge with virulent wild-type virus. These influenza A reassortant virus vaccines also express the ca and temperature sensitivity (ts) phenotypes in vitro, but the genes of the ca virus parent which specify the ca, ts, and attenuation (att) phenotypes have not adequately been defined. To identify the genes associated with each of these phenotypes, we isolated six single-gene substitution reassortant viruses, each of which inherited only one RNA segment from the ca parent virus and the remaining seven RNA segments from the A/Korea/1/82 (H3N2) wild-type virus parent. These were evaluated in vitro for their ca and ts phenotypes and in ferrets, hamsters, and seronegative adult volunteers for the att phenotype. We found that the polymerase PA gene of the ca parent specifies the ca phenotype and that the PB2 and PB1 genes independently specify the ts phenotype. The PA, M, PB2, and PB1 genes of the ca donor virus each contribute to the att phenotype. The finding that four genes of the ca donor virus contribute to the att phenotype provides a partial explanation for the observed phenotypic stability of ca reassortant viruses following replication in humans.
Natural protection from cholera is associated with local intestinal antibacterial and antitoxic antibodies, which appear to act synergistically. Although current parenteral cholera vaccines offer insufficient protection, new vaccines administered orally have more promise. Killed Vibrio cholerae, alone or given with the B subunit of cholera toxin, was evaluated in adult volunteers. Vaccinees, who received three doses of either vaccine, and unvaccinated controls ingested 10(6) V. cholerae organisms to determine the protective efficacy of the vaccines. The combination vaccine provided 64% protection, and the whole vibrio vaccine given alone provided 56% protection. In addition, illnesses in vaccines were milder than those in controls, and both vaccines gave complete protection against more severe disease. This substantial level of protection against a dose of V. cholerae that caused cholera in nearly 90% of controls suggests that these vaccines might provide at least as high a level of protection if given to the population of an endemic area. Indeed, a field efficacy trial is underway in Bangladesh, and preliminary data indicate a protective efficacy of 85% for a killed whole vibrio plus B subunit vaccine similar to that tested in volunteers and an efficacy of 58% for the killed whole vibrio vaccine alone. Thus, the studies in human volunteers were successful in predicting the substantial protection afforded by the vaccines in a cholera endemic area.
Objective: To evaluate the influence of a human immunodeficiency virus (HIV) vaccine given to uninfected volunteers on the interpretation of serodiagnostic HIV test results. Design: Retrospective cohort study. Setting: 5 AIDS Vaccine Evaluation Units funded by the National Institute of Allergy and Infectious Diseases. Participants: The first 266 healthy adult volunteers (aged 18 to 60 years) who did not have HIV infection and whose history suggested that they were at low risk for acquiring HIV infection. Measurements: HIV antibody was measured by enzyme-linked immunosorbent assay (ELISA) and Western blot test, the results of which were interpreted on the basis of four different published criteria. Results: At some time during the first 12 months of the vaccine studies, 68% of volunteers were positive for HIV antibodies by ELISA. Depending on criteria used to interpret Western blot test results, 0% to 44% of volunteers had positive results that might have caused them to be incorrectly labeled as HIV infected. Conclusions: Significant social risks to volunteers participating in HIV vaccine studies were identified. Persons interpreting HIV serodiagnostic test results must consider that an HIV vaccine can cause a positive result in persons who are not infected.
Two strains of Campylobacter jejuni ingested by 111 adult volunteers, in doses ranging from 8 × 102 to 2 × 109 organisms, caused diarrheal illnesses. Rates of infection increased with dose, but development of illness did not show a clear dose relation. Resulting illnesses with strain A3249 ranged from a few loose stools to dysentery, with an average of five diarrheal stools and a volume of 509 mL. Infection with strain 81–176 was more likely to cause illness, and these illnesses were more severe, with an average of 15 stools and 1484 mL of total stool volume. All patients had fecal leukocytes. The dysenteric nature of the illnesses indicates that the pathogenesis of C. jejuni infection includes tissue inflammation. III volunteers developed a serum antibody response to the C. jejuni group antigen and were protected from subsequent illness but not infection with the same strain.
Abstract : A long-term program has been undertaken to develop effective immunizing agents to control enterotoxigenic Escherichia coli (ETEC) diarrheal disease. Acute traveler's diarrhea is a major cause of loss of effectiveness in United States Military personnel assigned in less-developed areas and that ETEC are the most frequent etiologic agent of acute travelers' diarrhea. Two separate approaches are being followed to develop vaccines against ETEC. One involves purification of colonization factor antigen fimbriae (pili) and their use as oral vaccines. The second approach involves a genetically-engineered non- enterotoxigenic strain to be used as an oral vaccine. Another major pathogen responsible for traveler's diarrhea and dysentery in military personnel is Shigella. A close collaboration with the Department of Bacterial Diseases of the Walter Reed Army Institute of Research involves clinical studies to access the safety, immunogenicity and efficacy of candidate oral Shigella vaccines developed by Dr. S.B Formal and co-workers in the Department of Bacterial Diseases at WRAIR.
We evaluated the abilities of three different avian influenza A viruses to attenuate the wild-type human influenza A/Korea/1/82 (H3N2) virus in squirrel monkeys, chimpanzees, and adult seronegative human volunteers. Two of these, avian influenza A/Mallard/NY/78 and A/Mallard/Alberta/76 viruses, appeared to be satisfactory donors of attenuating genes for the production of live influenza A reassortant virus vaccines for human use because the reassortants exhibited an acceptable balance between attenuation and immunogenicity.
Short-term consumption of a high-fat diet impairs exercise capacity in both rats and humans, and increases expression of the mitochondrial uncoupling protein, UCP3, in rodent cardiac and skeletal muscle via activation of the transcription factor, peroxisome proliferator-activated receptor α (PPARα). Unlike long-chain fatty acids however, medium-chain fatty acids do not activate PPARα and do not increase muscle UCP3 expression. We therefore investigated exercise performance and cardiac mitochondrial function in rats fed a chow diet (7.5% kcal from fat), a long-chain triglyceride (LCT) rich diet (46% kcal from LCTs) or a medium-chain triglyceride (MCT) rich diet (46% kcal from MCTs). Rats fed the LCT-rich diet for 15 days ran 55% less far than they did at baseline, whereas rats fed the chow or MCT-rich diets neither improved nor worsened in their exercise capacities. Moreover, consumption of an LCT-rich diet increased cardiac UCP3 expression by 35% and decreased oxidative phosphorylation efficiency, whereas consumption of the MCT-rich diet altered neither UCP3 expression nor oxidative phosphorylation efficiency. Our results suggest that the negative effects of short-term high-fat feeding on exercise performance are predominantly mediated by long-chain rather than medium-chain fatty acids, possibly via PPARα-dependent upregulation of UCP3.
An avian-human reassortant influenza A virus deriving its genes coding for the hemagglutinin and neuraminidase from the human influenza A/Washington/897/80 (H3N2) virus and its six "internal" genes from the avian influenza A/Mallard/NY/6750/78 (H2N2) virus (i.e., a six-gene reassortant) was previously shown to be safe, infectious, nontransmissible, and immunogenic as a live virus vaccine in adult humans. Two additional six-gene avian-human reassortant influenza viruses derived from the mating of wild-type human influenza A/California/10/78 (H1N1) and A/Korea/1/82 (H3N2) viruses with the avian influenza A/Mallard/NY/78 virus were evaluated in seronegative (hemagglutination inhibition titer, less than or equal to 1:8) adult volunteers for safety, infectivity, and immunogenicity to determine whether human influenza A viruses can be reproducibly attenuated by the transfer of the six internal genes of the avian influenza A/Mallard/NY/78 virus. The 50% human infectious dose was 10(4.9) 50% tissue culture infectious doses for the H1N1 reassortant virus and 10(5.4) 50% tissue culture infectious doses for the H3N2 reassortant virus. Both reassortants were satisfactorily attenuated with only 5% (H1N1) and 2% (H3N2) of infected vaccines receiving less than 400 50% human infectious doses developing illness. Consistent with this level of attenuation, the magnitude of viral shedding after inoculation was reduced 100-fold (H1N1) to 10,000-fold (H3N2) compared with that produced by wild-type virus. The duration of virus shedding by vaccines was one-third that of controls receiving wild-type virus. At 40 to 100 50% human infectious doses, virus-specific immune responses were seen in 77 to 93% of volunteers. When vaccinees who has received 10(7.5) 50% tissue culture infectious doses of the H3N2 vaccine were experimentally challenged with a homologous wild-type human virus only 2 of 19 (11%) vaccinees became ill compared with 7 of 14 (50%) unvaccinated seronegative controls ( P < 0.025; protective efficacy, 79%). Thus, three different virulent human influenza A viruses have been satisfactorily attenuated by the acquisition of the six internal genes of the avian influenza A/Mallard/NY/78 virus. The observation that this donor virus can reproducibly attenuate human influenza A viruses indicates that avian-human influenza A reassortants should be further studied as potential live influenza A virus vaccines.
