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Biomedical subjects

R M Chanock

Publications and source records attributed to R M Chanock.

At least 199 records · Page 11Linked to original sources

Experimental respiratory syncytial virus pneumonia in cebus monkeys.

Into 14 juvenile cebus monkeys that lacked serum antibodies for RS virus 10(8) plaque-forming units (pfu) of wild-type respiratory syncytial (RS) virus were inoculated transtracheally. Roentgenographic evidence of pneumonia developed in 13 of 14 infected animals. Gross pathologic changes occurred in each of the 13 monkeys that were sacrificed. Patchy areas of red consolidation were seen in the lower lobes 24 hours after inoculation, and there was progression to gray consolidation seven days later. Each of the infected animals had histologic evidence of interstitial pneumonia. Changes were detected in the lung as early as 24 hours after inoculation; they consisted primarily of infiltration of the alveolar wall. By the fourth to sixth day after inoculation there was marked interstitial thickening, pulmonary consolidation, formation of multinucleated giant cells and development of eosinophilic cytoplasmic inclusion bodies within alveolar cells. RS viral antigens, detected by indirect immunofluorescence, were distributed throughout cells of the alveolar wall and the bronchiolar epithelium. The virus grew to highest titer in the lungs on the fourth to sixth day after inoculation; up to 10(8) pfu/gram of tissue were detected. The cebus monkey represents the first experimental host to develop extensive pulmonary lesions during infection with respiratory syncytial virus.

Animals↗

Experimental infection of chimpanzees with the Norwalk agent of epidemic viral gastroenteritis.

A fecal filtrate of human origin containing the Norwalk agent of epidemic viral gastroenteritis was administered by stomach tube to chimpanzees in an attempt to induce diarrheal disease. Significant postchallenge serum antibody rises against Norwalk viral antigens were demonstrated in all animals using the techniques of immune electron microscopy and radioimmunoassay. In addition, viral antigens were detected in feces from five of nine animals using radioimmunoassay. Clinical illness characterized by diarrhea and/or vomiting did not occur. Infection was transmitted subsequently by feeding four additional chimpanzees a fecal filtrate prepared from one of the previously infected animals. Development of an antibody response in four animals and detection of viral antigen in two animals that received this passage filtrate indicated that viral replication had occurred in the absence of clinical illness. The availability of the chimpanzee as an experimental animal host susceptible to infection with the Norwalk agent should facilitate the study of epidemic viral gastroenteritis.

Animals↗

Solid-phase microtiter radioimmunoassay for detection of the Norwalk strain of acute nonbacterial, epidemic gastroenteritis virus and its antibodies.

The development of microtiter solid-phase radioimmunoassays for the detection of Norwalk antigen and its antibody is described. The tests are simple to perform and are sensitive and specific. The test for antigen can be used on crude stool filtrates and suspensions. Both tests are at least as sensitive as immune electron microscopy and more sensitive than immune adherence assay.

Animals↗

Prevalence of antibody to the Norwalk agent by a newly developed immune adherence hemagglutination assay.

An immune adherence hemagglutination assay (IAHA) for the detection of antibody to the Norwalk agent of acute epidemic nonbacterial gastroenteritis was developed using as antigen virus purified from stool from an experimentally infected volunteer. The assay was sensitive and specific and was efficient for detecting Norwalk antibody seroresponses. The prevalence of Norwalk antibody in various groups in the United States was studied. Antibody to the Norwalk agent was acquired gradually, beginning slowly in childhood and accelerating in the adult period so that by the fifth decade 50% possessed antibody. This pattern of antibody acquisition contrasted sharply with that for the human rotavirus of infantile gastroenteritis. Rotavirus antibody was acquired during early childhood by almost all individuals in the pediatric groups studied. Antibody to the Norwalk agent was also found in rural Bangladesh; in a small prevalence survey of 39 children and adults 21% possessed Norwalk IAHA antibody, whereas 95% possessed antibody to the human rotavirus.

Adolescent↗

Evaluation of five temperature-sensitive mutants of respiratory syncytial virus in primates: II. Genetic analysis of virus recovered during infection.

Five temperature-sensitive (ts) mutants of respiratory syncytial (RS) virus (ts-1, ts-1 NG-1, ts-1 NG-16, ts-2, and ts-7), previously evaluated forinfectivity and virulence in chimpanzees and owl monkeys, were also assayed for in vivo genetic stability. None of the five mutants tested was completely stable genetically. Thus, virus which had lost some or all of the ts property was recovered from each infected chimpanzee. Significantly, each ts-1 NG-1 isolate retained some degree of temperature sensitivity and hence was not true wild-type virus. Clonal analysis of viruses shed by ts-1, ts-1 NG-1, ts-1 NG-16, or ts-7 infected chimpanzees indicated that in most instances only a minority of the virus shed was altered genetically. Of five chimpanzees infected with the ts-2 mutant, three shed only ts virus, and the remaining two chimpanzees shed only ts+ virus. Such ts+ virus proved to be avirulent when evaluated in chimpanzees or owl monkeys, indicating that loss of the ts property did not restore virulence. Based upon these findings, the ts-2 mutant appears to be a suitable candidate for clinical trials in man.

Animals↗

Growth and genetic stability of 4 temperature sensitive (ts) mutants of respiratory syncytial (RS) virus in newborn ferrets.

Four temperature sensitive (ts) mutants of respiratory syncytial (RS) virus were evaluated for growth and genetic stability in newborn ferrets. ts-1, the mutant previously tested in children as a possible live virus vaccine and found to be insufficiently attenuated for the upper respiratory tract, grew in the lungs of newborn ferrets to the same peak titer as wild type RS virus. In addition some genetic alteration of the ts-1 mutant occurred. Two more defective subclones of ts-1, ts-1 NG-1 and ts-1 NG-16, were greatly restricted in growth in the ferret's lungs. ts-1 NG-16 was also restricted in the nasal turbinates, but ts-1 NG-1 grew to high titer in the nasal turbinates. Growth of ts-1 NG-1, however, was delayed 2 weeks compared to the growth of wild type virus. Genetic alteration occurred during growth of either subclone; the virus isolated was intermediate between wild type and input virus in plaque forming ability at restrictive temperatures. In no instance was wild type virus isolated from the ferrets infected with either subclone. ts-2, a plaque morphology mutant that does not fuse cells to form syncytia even at the permissive temperature of 32 degrees C, was restricted in growth in both the lungs and nasal turbinates, and genetically altered virus was not recovered from these animals. Of the mutants tested, ts-2 was the most restricted mutant in the newborn ferret and should be evaluated further as a candidate vaccine virus.

Animals↗

Secretory antibody directed against rotavirus in human milk--measurement by means of enzyme-linked immunosorbent assay.

Human milk contains antibodies to a variety of enteropathic agents. We utilized the method of enzyme-linked immunosorbent assay to investigate anti-rotavirus secretory IgA in 113 human milk and colostral specimens from a rural area in Guatemala, 32 colostral specimens from an urban area of Costa Rica, and 12 from an urban area of the United States. Anti-rotavirus SCIgA was found in all colostral samples and in 94% of the milk specimans. Both the absolute concentration of anti-rotavirus SCIgA and concentration relative to total SCIgA were highest in colostrum, falling to lower but detectable levels from one week to two years after birth. No significant differences were noted in the results from the specimens from the three different geographic areas. The possible role of this antibody in immunity to rotavirus infections is discussed.

Antibodies, Bacterial↗

Immunological response to infection with human reovirus-like agent: measurement of anti-human reovirus-like agent immunoglobulin G and M levels by the method of enzyme-linked immunosorbent assay.

The report describes the development of an enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against the human reovirus-like agent of infantile gastroenteritis (HRVLA). This ELISA system proved to be four times as sensitive as the standard anti-HRVLA fluorescent-antibody assay and ten times as sensitive as the standard anti-HRVLA complement fixation assay. In addition, the ELISA was capable of determining immunoglobulin G (IgG) and IgM subclasses of anti-HRVLA antibody using a single dilution os serum. With this assay, it was discovered that 11 of 21 infected children had anti-HRVLA IgM in their acute sera before the appearance of anti-HRVLA IgG. ELISA is a useful tool in the evaluation of immunological response to HRVLA infection.

Adult↗

Enzyme-linked immunosorbent assay for measurement of serological response to respiratory syncytial virus infection.

An enzyme-linked immunosorbent assay was applied to the detection of serum antibodies against respiratory syncytial virus. The end points of the various sera tested in the assay were approximately 100 times higher than in the complement-fixation test and 2 to 4 times higher than in the plaque reduction test. In addition, the immunosorbent assay appeared to be more efficient than the plaque reduction and complement-fixation techniques for detecting a serological response in young infants (1 to 6 months old) with serous respiratory syncytial virus lower respiratory disease. The simplicity, sensitivity, and rapidity of the enzyme-linked immunosorbent assay make it a useful tool for immunological studies with respiratory syncytial virus.

Antibodies, Viral↗

Temperature-sensitive mutants of influenza A virus: production and characterization of A/Victoria/3/75-ts-1[E] recombinants.

The Hong Kong/68-ts-1[E] virus, which has a 38 degrees C shutoff temperature for plaque formation, has been proposed as a donor of its two ts lesions to new variants of influenza A virus that pose an epidemic threat. To further examine whether the acquisition of the two ts-1[E] lesions will predictably attenuate new influenza A variants, the HK/68-ts-1[E] virus was mated with the A/Vic/3/75 wild-type virus. The Vic/75-ts-[E] recombinants that had the two ts-1[E] lesions also had a 38 degrees C shutoff temperature. Two Vic/75-ts-1[E] recombinants (clones 81 and 113) that had the two ts-1[E] lesions, a 38 degrees C shutoff temperature, and the Vic/75 hemagglutinin and neuraminidase glycoproteins were similar to each other and to their ts-1[E] parent in the pattern of replication and genetic stability in hamsters. These findings support the hypothesis that the acquisition of the two ts-1[E] lesions will predictably attenuate wild-type influenza A virus. Each Vic/75-ts-1[E] recombinant virus that possessed only the group 1 ts-1[E] lesion had a 39 degrees C shutoff temperature. Two of three of the Vic/75-ts-1[E] recombinants that had only the group 2 ts-1[E] lesion had a 39 degrees C shutoff temperature. This suggests that the HK/68-ts-1[E] donor virus contains two ts genes each of which by itself restricts plaque formation at 39 degrees C and above. The HK/68-ts-1[E] parent virus and its Vic/75 recombinant clones 81 and 113 were evaluated in ferret tracheal organ cultures maintained at permissive and restrictive temperatures. The Vic/75-ts-1[E] clone 81 differed from its parent and sister clone 113 in that it replicated readily and caused ciliostasis at 37 degrees C, a temperature restrictive for the replication of other ts-1[E] recombinants with a 38 degrees C shutoff temperature. The genetic basis underlying this difference was not elucidated.

Antigens, Viral↗

Temperature-sensitive mutants of influenza A virus: evaluation of A/Victoria/3/75-ts-1[E] recombinant viruses in volunteers.

The Hong Kong/68-ts-1[E] virus and its Udorn/72 and Georgia/74 recombinants, which have a 38 degrees C shutoff temperature and a ts lesion(s) on the genes coding for the P3 and NP proteins, were adequately attenuated and immunogenic in adult volunteers who lacked serum hemagglutination-inhibiting antibody (titer, </=1:8), but who possessed serum neuraminidase-inhibiting antibody. Two Victoria/75-ts-1[E] clones that also had a 38 degrees C shutoff temperature and a ts lesion(s) on the same two genes were administered to adult volunteers who lacked both serum hemagglutination-inhibiting antibody (titer, </=1:8) and neuraminidase-inhibiting antibody (titer, </=1:4). In contrast to the behavior of the earlier ts-1[E] recombinants, the Vic/75-ts-1[E] recombinants retained the capacity to cause febrile, systemic illness. However, the recombinants were attenuated compared with wild-type virus. The Vic/75-ts-1[E] virus vaccinees shed a larger amount of virus for a longer time than the previous ts-1[E] vaccinees, but they shed less virus than volunteers infected with wild-type virus. The ts-1[E] virus shed retained its ts phenotype in most instances and failed to spread to susceptible contacts. Vaccinees were partially protected against homologous wild-type virus challenge. The failure of HK/68, Udorn/72, and Georgia/74 ts-1[E] vaccinees to develop systemic reactions may reflect the presence of neuraminidase immunity before infection. In this situation, attenuation probably resulted from the degree of defectiveness of the ts-1[E] recombinant virus and the existence of neuraminidase immunity in the recipients. The 50% human infectious dose of the Vic/75 ts-1[E] virus was less than 10(5.2) 50% tissue culture infective doses. This suggests that at the time of a pandemic shift involving both the hemagglutinin and neuraminidase glycoproteins, a small amount of live virus vaccine might be effective in initiating infection.

Antibodies, Viral↗

Experimental production of respiratory tract disease in cebus monkeys after intratracheal or intranasal infection with influenza A/Victoria/3/75 or influenza A/New Jersey/76 virus.

A total of 28 cebus monkeys were inoculated intratracheally or intranasally with 10(6) 50% tissue culture infective doses of A/New Jersey/76 virus or 10(7) 50% tissue culture infective doses of A/Victoria/75 virus, and 8 additional monkeys received sterile allantoic fluid. Each of the animals became infected as evidenced by a serological response and/or shedding of the virus. Of the 10 animals inoculated intratracheally with A/Victoria/75 virus, 8 developed a systemic illness, and pulmonary infiltration was detected by X-ray in 7 of the 8. Administration of A/New Jersey/76 virus intratracheally to 10 monkeys produced a mild systemic illness in 2 animals and an upper respiratory tract illness in 6, but no illness developed in the remaining 2 monkeys; none of the animals developed X-ray evidence of lower respiratory tract disease. Intranasal administration of either virus failed to induce any illness or produced, at most, mild illness confined to the upper respiratory tract. These studies demonstrate that cebus monkeys are susceptible to respiratory tract infection with influenza A viruses and that the development of pulmonary disease is reflected in the appearance of easily recognizable radiological changes.

Animals↗

Measurement of rotavirus antibody by an enzyme-linked immunosorbent assay blocking assay.

A new method for the measurement of rotavirus antibody is described, utilizing the system of enzyme-linked immunosorbent assay (ELISA). In this method, serum is incubated with a fixed amount of rotavirus antigen, and the amount of antibody is determined by measuring the amount of unneutralized antigen. Such an assay system proved to be as efficient as the other available rotaviral antibody systems. The ELISA blocking assay also has the advantages of not requiring purified or gnotobiotic antigen and of being able to measure rotaviral antibody in all animal species.

Adult↗

The pathogenesis of respiratory syncytial virus infection in cotton rats.

The cotton rat is susceptible to respiratory synctial virus infection in both the upper and lower portions of the respiratory tract. Virus replicates to high titer in the nose and lungs and to relatively low titer in the trachea. Immunofluorescence studies demonstrated viral antigen in the nasal epithelium and the bronchial and bronchiolar epithelium but not in the trachea or the alveolar cells of the lungs. Histopathologic changes included a desquamative, exudative rhinitis of moderate severity and a mild proliferative bronchiolitis. Serum neutralizing antibody developed in all animals by the ninth day after infection, reaching extremely high titer in several instances. Unlike the previously described response of experimentally infected infant ferrets, cotton rats are uniformly susceptible to pulmonary infection throughout life, thereby offering a model for long-term pulmonary studies heretofore not available.

Animals↗