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Biomedical subjects

G K HIRST

Publications and source records attributed to G K HIRST.

At least 19 recordsLinked to original sources
PubMed1954

The experimental production of combination forms of virus. III. The formation of doubly antigenic particles from influenza A and B virus and a study of the ability of individual particles of X virus to yield two separate strains.

The simultaneous inoculation of influenza A and B strains into eggs was found to result in the formation of virus which had antigenic properties of both parent strains. The hemagglutinin of the new virus could be inhibited by both A and B antisera and the agent was also neutralized by both sera. This X particle displayed the characteristics of what we have previously called X(1). It did not reproduce itself on multiplying in the egg, but instead yielded parent types. Limiting infectious dilutions of influenza virus were studied in eggs by inoculating two different strains at once to act as markers for singly or doubly initiated infections. A base line was thus established for the frequency of single and mixed infections at virus dosages which were fractions of one ID(50). These frequencies were compared with those obtained with X viruses. X(1) virus from A-B infections did not initiate an unusual number of mixed infections at the end point. By contrast, X(1) and X(2) (M-W type) gave much higher numbers of mixed infections than did the control virus. In the discussion it is proposed (a) that doubly antigenic viruses are due to an effect known as phenotypic mixing and (b) that the ability of individual virus particles to give rise to two separate strains is due to heterozygosis or diploidy.

Antigens, Viral↗
PubMed1953

The experimental production of combination forms of virus. I. Occurrence of combination forms after simultaneous inoculation of the allantoic sac with two distinct strains of influenza virus.

The fact that the hemagglutination inhibition test will not detect more than one component in an artificial mixture of two antigenically distinct strains of virus was demonstrated experimentally. With this proved, the inference seemed justified that the inhibition of the hemagglutinin of a virus suspension by each of two antisera, specific for differing strains of virus, would be an indication that some of the specific antigenic components from each of these viruses were both present in single particles of the virus suspension. Two pair of influenza A strains were used to simultaneously inoculate the allantoic sac, and some embryos thus infected yielded virus which had its hemagglutinin inhibited by sera specific against each of the parent forms. Such doubly inhibitable hemagglutinin contributed as much as 84 per cent of the total hemagglutinin in certain fluids. Each of the specific antisera inhibited the hemagglutinin of the combination form very nearly as well as it inhibited its own hemagglutinin.

Antigens↗
PubMed1953

The experimental production of combination forms of virus. II. A study of serial passage in the allantoic sac of agents that combine the antigens of two distinct influenza A strains.

Double infection of the allantoic sac with Melbourne and WSN viruses induced the formation of a combination virus, which had some of the antigenic properties of both parents and which maintained itself through serial passage in the chorioallantoic sac. In the course of prolonged passage in the egg, three varieties of combination virus were found. The first (X(1)) occurred in ten passages and was characterized as follows: X(1) was produced in and could be successfully passed from those chick embryos that had received very large inocula of virus. The X(1) hemagglutinin was efficiently inhibited by both M and W antisera. Each passage fluid, containing X(1) as the predominant strain, also contained large amounts of the parent forms M and W. It is very likely that X(1) reverted to parent types of virus at a high rate. The second variety (X(2)) arose from the passage series of X(1) and was carried for approximately 20 passages without definite alteration in its character. It differed from X(1) in that it had the ability to appear as the predominant form occasionally in embryos that had received a limiting infective dilution of virus. Because of this, it seems probable that X(2) reverted to parent types at a slower rate than X(1). Like X(1), this virus was never obtained in pure form and suspensions in which it predominated contained large amounts of M and W, especially the former. Good evidence was obtained that X(2) reverted to M and W virus while multiplying in the chorioallantoic sac. X(3) was derived from passage of X(2) virus after 32 transfers and can be characterized in several ways: (a) X(3) yielded the only X(3) fluids on passage in eggs. This was in striking contrast to X(2) which could not be passed without giving rise to some fluids in which M and W predominated, (b) The X(3) hemagglutinin was weakly inhibited by all but the highest concentrations of M serum, but was strongly inhibited by W serum. X(2) was readily inhibited by relatively small amounts of both sera. (c) X(3) virus, after several passages at limiting dilutions, was neutralized to a highly significant degree by specific M and W sera. This is not necessarily an essential difference from the behavior of X(2) since technical difficulties (large amounts of M and W in X(2) fluids) may have prevented the demonstration of equally striking double neutralization of this virus, (d) After five limiting dilution passages, the X(3) virus retained the characteristics listed under (a) to (c). It is felt that the foregoing facts justify the conclusion that X(3) is a stable virus which combines some of the specific antigens of two parent types.

Animals↗
PubMed1952

Strain-specific elements in influenza antigens.

Rabbit antisera were prepared against ten antigenically different influenza A strains. These sera were absorbed with one or more heterologous strains and in each case all the heterologous or crossing antibody was removed; the anti-bodies remaining after this treatment were specific for the immunizing strain or group of strains. On the basis of reactions with absorbed sera, the strains fell into seven groups. Absorbed specific antisera of these groups were used to test the HI titer against a large number of influenza A viruses. Most of the strains were inhibited by a single serum, a few were inhibited by none of the sera, and only one strain was inhibited by two antisera. The grouping of strains by this method was less equivocal than classifications based on previous tests. When more fully developed, this technique promises to be of interest and assistance in the study of influenza, especially from the epidemiological and prophylactic standpoints.

Animals↗