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Biomedical subjects

K F Shortridge

Publications and source records attributed to K F Shortridge.

At least 91 records · Page 5Linked to original sources
PubMed1982

Avian influenza A viruses of southern China and Hong Kong: ecological aspects and implications for man.

Continuous surveillance of the influenza viruses isolated from domestic poultry from southern China and Hong Kong over more than 4 years resulted in the isolation of influenza viruses possessing 46 different combinations of haemagglutinin (H) and neuraminidase (N) subtypes. Of these, 43 were obtained from ducks from China. In all cases, infection appeared to be asymptomatic. The antigenic combination found most commonly in the viruses isolated was H4N6, which accounted for approximately one-quarter of the duck isolates, its occurrence being more frequent than expected from a statistical analysis of the observed frequencies of the haemagglutinin and neuraminidase genes among all the isolates. Some combinations of H and N occurred less frequently than expected or not at all. Influenza viruses tended to be isolated more frequently from ducks during the summer months in comparison with paramyxoviruses, which were more commonly encountered in the winter. Possible reasons for the great antigenic diversity of influenza A viruses in the poultry, especially the ducks, in the region are discussed together with the potential significance of these viruses to the emergence of human influenza pandemics.

Animals↗
PubMed1982

Multiple avian influenza infection: selection of a non-avid virus by a heterologous avian host.

Experimental infection of domestic fowl, ducks and geese with an influenza A virus (H7N2) isolated from a domestic duck showed that this virus was apathogenic for these poultry. A second virus (H6N2), also apathogenic and more 'non-avid' than any such isolates previously recognised in surveillance of domestic poultry in Hong Kong, was isolated from one goose after H7N2 shedding had ceased. This goose, in effect, acted as a selective isolation system for the H6N2 virus whose presence in the field isolate could not be detected in spite of multiple passage in embryonated eggs.

Animals↗
PubMed1980

Isolation and properties of viruses from poultry in Hong Kong which represent a new (sixth) distinct group of avian paramyxoviruses.

Eight viruses isolated in Hong Kong were shown to be serologically related. One was obtained from the tracheal swab of a chicken and four were from cloacal swabs of ducks sampled at a poultry dressing plant. Three isolations were made from samples taken at a duck farm: two from pond water and one from faeces. Representatives of these isolates were shown to be paramyxoviruses but were serologically distinct from other avian and mammalian paramyxoviruses by haemagglutination inhibition and neuraminidase inhibition tests. Slight variations were seen in the properties of three isolates examined in detail. All three were apathogenic for chickens. The structural polypeptides of one isolate, PMV-6/duck/Hong Kong/199/77, were examined by SDS-polyacrylamide gel electrophoresis. Seven polypeptides were detected, with mol. wt. 180000, 76000, 60000, 55000, 51000, 48000 and 40000. The isolates represent a sixth serologically distinct avian paramyxovirus group.

Animals↗
PubMed1980

Isolation of ortho- and paramyxoviruses from domestic poultry in Hong Kong between November 1977 and October 1978 and comparison with isolations made in the preceding two years.

Regular surveillance of domestic poultry from Hong Kong and southern China for influenza A viruses was conducted in Hong Kong from November 1977 to October 1978. Tracheal or cloacal swabs taken from 2844 ducks, geese and fowls yielded 141 influenza viruses of which 135 were derived from ducks. The isolation rate from ducks was twice as high from the cloaca (12.1 per cent) as from the trachea (5.8 per cent). The overall frequency of isolation was 10.3 per cent and 2.3 per cent for poultry originating from southern China and Hong Kong, respectively. Fourteen of the influenza antigenic combinations recorded in this period of surveillance had been obtained in the previous two years while five were new--H2N2, H2Nav6, Hav5N2, Hav6Nav1 and Hav7Nav4. The number of combinations recorded over three years was 39, the most frequent being Hav4Nav1 which comprised one fifth of the total. All the combinations found in geese and fowl isolates, apart from Hav7Nav6 found in a fowl, have been recorded in duck isolates. Faecal/oral transmission of virus from infected pond water was thought to be an important factor in the high incidence of influenza in ducks. The existence of a large number of combinations of haemagglutinin and neuraminidase antigens and the isolation of two viruses from the cloaca suggest that recombination is occurring in these birds. Reasons for the limited isolation of some antigenic combinations are considered. The paramyxoviruses, Newcastle disease virus and the Hong Kong avian paramyxovirus, were also isolated. Over the three year period the isolation rate of influenza and paramyxoviruses from ducks appeared to be cyclical and seasonal. Influenza was found mainly in the summer and paramyxoviruses in the winter.

Animals↗
PubMed1979

Properties of a newly isolated, serologically distinct avian paramyxovirus.

The morphological, bio-physical and growth properties of the isolate duck/Hong Kong/D3/75 (D3/75) were consistent with this virus being a member of the paramyxovirus group. Using haemagglutination inhibition and neuraminidase inhibition tests no serological relationships between D3/75 and other paramyxoviruses could be demonstrated. The structural polypeptides of D3/75 were also typical of paramyxoviruses, consisting of 6--7 polypeptides ranging in molecular weight from 46,000--200,000 under reduced conditions. Two polypeptides were glycosylated.

Animals↗
PubMed1979

Seroepidemiology of rubella infection in Chinese and Caucasians in Hong Kong.

The seroepidemiology of rubella infection in Hong Kong Chinese was examined by haemagglutination inhibition of normal sera and a comparison made where feasible with Caucasians living in Hong Kong. Taking reciprocal titre of 20 as a baseline, the incidence of maternally acquired antibody was 84% for Chinese and 90% for Caucasians. In babies up to 2 months this incidence was maintained in Caucasians but declined to 54% in Chinese. High titre antibody was more frequently detected in Caucasians generally, including women of child-bearing age. The detection of rubella-specific IgM in the Caucasian babies was suggestive of recent maternal infection. However, fewer Caucasian (20%) than Chinese (36%) women of child-bearing age (15-40 years) appeared unprotected against rubella. When all age groups were considered, 88% of Caucasians and 53% of Chinese were seropositive. The occurrence of a rubella outbreak during the study did not give rise to a significant increase in the incidence of seropositivity in Chinese 19-25 years, the only age group able to be evaluated in this manner. The ethnic differences in seroepidemiology are considered in the light of known HLA-1 and HLA-8 antigen distributions in Caucasian and Mongoloid people and the apparently low incidence of congenitally acquired rubella in Chinese.

Adolescent↗
PubMed1979

Further studies of the antigenic properties of H3N2 strains of influenza A isolated from swine in South East Asia.

H3N2 strains of influenza A isolated from swine in Hong Kong were compared with human strains of H3N2 influenza A variants in reciprocal HI tests using ferret sera. One isolate from swine was indistinguishable from A/Hong Kong/68, one set of viruses isolated in 1976 and 1977 was most related to A/Hong Kong/68 but was not identical to it, two isolates from 1976 were 'bridging strains' that cross-reacted equally with the contemporary variants A/Victoria/3/75 and A/Texas/1/77, similarly to a small number of recent human isolates, and two isolates from 1977 were similar to A/Victoria/3/75. These general relationships were supported by neuraminidase inhibition tests. The findings confirm and extend previous results indicating that swine may be a reservoir of old and novel variants of influenza A H3N2 strains related to those that infect man.

Animals↗
PubMed1979

Interferon synthesis by human colostral leucocytes.

The antiviral potential of human colostral leucocytes was assessed by their capacity to produce interferon. Leucocytes cultured from colostrum were stimulated by mitogens or Newcastle disease virus (NDV) to produce interferon which, by metabolic and physicochemical criteria, corresponded to normal human leucocyte interferon. Prepartum cells produced higher levels than postpartum cells. Colostral cells were less efficient producers than blood leucocytes.

Cells, Cultured↗
PubMed1979

Geographical distribution of swine (Hsw1N1) and Hong Kong (H3N2) influenza virus variants in pigs in Southeast Asia.

Influenza viruses of the Hsw1N1 and H3N2 subtypes were isolated in Hong Kong from pigs originating from Hong Kong, People's Republic of China (PRC), Singapore, and Taiwan. The H3N2 isolates were from pigs from Hong Kong and PRC, whereas the Hsw1N1 isolates were from pigs from Hong Kong, PRC, Singapore and Taiwan. The hemagglutinins of the H3N2 isolates were similar to those of the earlier A/Hong Kong/1/68 and A/Port Chalmers/1/73 variants from man. The Hsw1N1 isolates were similar to the human A/New Jersey/8/76 virus. These studies extend the geographical range of Hsw1N1 influenza virus and suggest that pigs in southeast Asia, like those in North America, harbor Hsw1N1 influenza viruses. These findings underline the importance of pigs as potential reservoirs for future human pandemics by the continued isolation (in Asia) of H3N2 and Hsw1N1 influenza viruses.

Animals↗
PubMed1979

Diversity of influenza A virus subtypes isolated from domestic poultry in Hong Kong.

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.

Animals↗
PubMed1978

Identification of a swine influenza virus (Hsw1N1) isolated from a duck in Hong Kong.

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.

Animals↗
PubMed1978

Incidence and preliminary characterisation of a hitherto unreported, serologically distinct, avian paramyxovirus isolated in Hong Kong.

Twenty-seven apparent paramyxoviruses, unrelated to known avian paramyxoviruses, were isolated at a Hong Kong dressing plant from the trachea or cloaca of birds originating from Hong Kong and the People's Republic of China. A total of 2443 apparently healthy ducks, geese and fowls was sampled and isolation frequencies were 1.3%, 1.0% and 0.5% respectively. Twenty of the isolates were from the cloaca; 11 were obtained in association with Newcastle disease virus and one with an avian influenza virus. The majority of the isolations were made in the winter months. All 27 isolates were serologically related although 11 representative isolates differed slightly in haemagglutinin properties. A representative isolate was not pathogenic for chickens. A serological survey of poultry indicated a relatively low incidence of infection.

Animals↗
PubMed1978

Newcastle disease virus surveillance in Hong Kong on local and imported poultry.

Surveillance of apparently healthy ducks, geese and fowl originating in Hong Kong and the People's Republic of China at a poultry dressing plant in Hong Kong yielded 67 isolates of Newcastle disease virus. More than twice as many viruses were isolated from the cloaca than from the trachea. Twelve representative isolates were examined in virulence tests--all six of the fowl isolates and two of five duck isolates behaved as velogenic strains, the other four were lentogenic.

Animals↗