Biomedical subjects
Publications and source records attributed to R G Webster.
The isolation of influenza A viruses from unconcentrated lake water and from fecal samples on the shore of these lakes is reported for the first time. Influenza A viruses, representative of most of the major antigenic subtypes, co-circulate in ducks on the lakes.
The second phase of a 2-year influenza virus surveillance programme of domestic avian species in Hong Kong (up to October 1977) yielded influenza A virus, Newcastle disease virus, and Hong Kong paramyxovirus, as well as unidentified haemagglutinating agents. These viruses were isolated from the trachea or cloaca of apparently healthy domestic ducks, geese, and chickens originating from China and Hong Kong. Twenty-five combinations of haemagglutinin and neuraminidase surface antigens were identified from the 136 influenza A viruses isolated. Eight of the combinations do not appear to have been previously reported - Hav3Nav2, Hav4Nav2, Hav4Nav4, Hav4Nav5, Hav4Neq1, Hav6Nav4, Hav6Nav6, and Hav9Nav1. The existence of such a diverse pool of influenza virus genetic information may play a role in the emergence of new human pandemic strains.
Serological studies on domestic poultry originating from China and Hong Kong suggest that the H1N1 virus may have persisted in domestic chickens prior to its reappearance in man in 1977. Experimental infection of young, local strains of poultry provided equivocal evidence that 4-day-old chickens could be infected; virus was not recovered from infected 1-month-old chickens.
Antigenic variants of A/PR/8/34 [HON1] influenza virus were selected after a single passage of the parent virus in embryonated chicken eggs in the presence of monoclonal antibodies to this virus. The monoclonal antibodies were produced by a hybridoma and were specific for an antigenic determinant on the HA molecule of the parent virus. Seven antigenic variants were analyzed with 95 monoclonal anti-HA antibodies prepared in vitro in the splenic fragment culture system. Three subgroups of antigenic variants were distinguished. The antigenic changes were primarily recognized by monoclonal antibodies to the strain- specific determinants of the parental hemagglutinin (HA) molecule. Monoclonal antibodies to HA determinants shared (in an identical or cross-reactive form) by parental virus and more than three heterologous viruses of the HON1 and H1N1 subtypes were unable to recognize the antigenic change on the variants. Similarly, heterogeneous antibody preparations could not differentiate between parental and variant viruses. The results are compatible with the idea that the HA of PR8 has available a large repertoire of antigenic modifications that may result from single amino acid substitutions, and that antigenic changes can occur in the strain- specific determinants on the HA molecule in the absence of concomitant changes in the cross-reactive HA determinants. The findings suggest that antigenic drift, in order to be epidemiologically significant, probably requires a series of amino acid substitutions in, or close to, the antigenic area on the HA molecule.
Keratomycosis and infection of the anterior chamber with a Rhizopus sp (phycomycosis, mucormycosis) developed in a 24-year-old man following a perforating injury of the cornea with a soil-contaminated screwdriver. The infection was documented by positive cultures of the corneal wound and of the anterior chamber and by histopathologic studies. Phycomycosis of the eye usually occurs in the setting of systemically impaired host resistance. The patient had no underlying disease that wound predispose him to this infection but the treatment with topical 0.1% dexamethasone and triamcinolone acetonide suspension injected into the sub-Tenon's space following the injury may have impaired his local immunologic defenses. Excisional keratoplasty played an important role in the successful management of this case.
Twenty-two strains of influenza A virus isolated from caged birds which had been imported into Japan from India and Thailand and had died druing transportation to Tokyo. Serological tests divided these strains into two groups. Viruses in the first group contained Hav7 hemagglutinin and were related antigenically to A/duck/Ukraine/1/63 [Hav7 Neq2]; viruses in the second group contained Hav4 hemagglutining and were related to A/duck/Czech/56 [Hav 4 Nav 1]. All strains contained Neq2 neuraminidase that was closely related to that fo A/equine/Miami/1/63[Heq2 Neq2] and A/duck/Ukraine/1/63[Hav7 Neq2]. It was concluded that the strains in the first group were Hav7 Naq2 and those in the second group were Hav4 Neq2; both group of viruses showed antigenic drift from the prototype strains.
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An influenza A virus isolated from a duck during a recent surveillance study on commercial poultry from the People's Republic of China and the New Territories, Hong Kong, was shown to possess Hswl antigens related to that of the swine (Hsw1N1) influenza virus. The isolation of an Hsw1N1 influenza virus from ducks indicates that avian species, as well as pigs, may serve as a reservoir of this potential pathogen for humans. The virus was avirulent for ducks, turkeys, chickens, and pigs.
Twelve influenza A viruses, antigenically related to the Ho, H1 and Hsw1 subtypes, were isolated from cloacal samples of feral ducks in Canada. Antigenic comparisons showed that these viruses were most closely related to the recent HSW1N1 isolates from man and pigs, whereas in vivo pathogenicity tests revealed differences between the Hsw1N1 viruses from the ducks and those from humans and pigs. Antigenic characterization of 94 additional influenza A viruses from the ducks showed four haemagglutinin subtypes (Hav1, Hav4, Hav5 and Hav7), an unclassified haemagglutinin, and six neuraminidase subtypes (N1, N2, Neq2, Nav1, Nav2 and Nav5) in various combinations, some of which are novel and have not previously been reported. Three of these duck influenza viruses possessed a haemagglutinin antigenically related to that of classical fowl plaque virus. A much higher percentage of virus isolations were from juvenile ducks (18.5%) than from adults (5%). All of the ducks, from which viruses were isolated, appeared healthy at the time of sampling. Serological studies on a limited number of humans and domestic birds living in close proximity to the Canadian ducks revealed no evidence of interspecies transmission. Our findings suggest that these birds serve as a substantial reservoir of antigenically diverse influenza viruses, including isolates antigenically related to the current human and animal influenza viruses. This reservoir in nature may be perpetuated by a cycle involving annual infection of juvenile birds followed by transmission to the remaining susceptible birds until the next congregation during the breeding season.
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Antisera to the type-specific internal influenza virus matrix (M) protein of a type A influenza virus were produced in goats. In the presence of complement, anti-M serum was cytotoxic for target cells which were infected with a variety of serologically distinct type A influenza viruses, but did not react with type B influenza virus-infected cells. Absorption experiments indicated that anti-M serum detected a common antigen(s) on the surface of type A-infected cells. This serological cross-reactivity parallels the cross-reactivity observed for the cytotoxic T-cell response to type A viruses.
The A/Hong Kong/1/68 (H3N2) influenza virus which has not been isolated from man for several years, was recently isolated from pigs in Hong Kong. Influenza viruses similar to A/Victoria/3/75, which are currently circulating in man, were also isolated from pigs. Both above-mentioned viruses could be transmitted readily from pig to pig in experimental studies. The isolation of influenza viruses similar to A/Hong Kong/68 from pigs in 1976 suggests that pigs may serve as a potential reservoir for future human pandemics as well as a possible source of genetic information for recombination between human and porcine strains of influenza virus.
The purpose of this study was to characterize the clinical features of laboratory-confirmed influenza in 20 children and young adults with cancer who were receiving immunosuppressive therapy. Viruses isolated from pharyngeal and nasopharyngeal cultures were identified as the A/Hong Kong/1/68 strain or one of its variants, either A/England/42/72, A/Port Chalmers/1/73, or A/Victoria/3/75. Although the signs and symptoms of influenza in our patients were not unusual, the clinical course lasted twice as long as in the general population. Complications developed in only 3 patients and were related to secondary bacterial infections rather than influenza. An important sequelae of influenza was the interruption of cancer therapy in 16 patients for periods of 4 days to 3 1/2 weeks. The severity of influenza did not appear related to type or activity of malignancy or to duration or specific form of cancer therapy. Guidelines for the prevention and management of influenza in children with cancer are recommended.
An influenza A virus isolated from the cloaca of a common murre was characterized antigenically as H3N2 and was most closely related to the A/Port Chalmers/1/73 strain. Serological studies of sera collected from common murres in the area of virus isolation showed that 21 per cent of the birds had antibodies to Hong Kong influenza virus.
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