The growth characteristics of a series of influenza A viruses in the turbinates and lungs of hamsters was measured: in addition, the susceptibility of hamsters to infection by these viruses was also determined. These two criteria were used to give estimates of the growth potential of influenza viruses in hamsters, and the results were related to the incidence of transmission of virus from inoculated hamsters to cage-contacts. The results showed that strains of influenza virus reported as virulent for man tended to grow to higher titres in hamster nasal washings and lungs; were more infective for hamsters when inoculated by the intranasal route; and showed a high incidence of spread to cage-contacts. The methods could provide valuable measurements of virus attenuation and transmissibility for man, and the further exploitation of these techniques could facilitate the production and licensing of live, attenuated influenza virus vaccines.

Female mice were isoimmunized with homologous spermatozoa of the same strain. Hybrid cells that secrete monoclonal antibodies to mouse sperm isoantigens were generated by modified hybridoma techniques using a semi-solid Iscove's modified Dulbecco's medium containing methylcellulose for the initial cloning. Out of more than 1,000 colonies that were initially recovered for subculture, 246 were shown to produce antibodies reacting with various cytological regions of mouse spermatozoa, when methanol-fixed sperm were employed in an indirect immunofluorescent assay. More than 75% of the generated monoclonal isoantibodies were shown to bind the acrosomal regions of mouse spermatozoa. Some were found to cross-react with spermatozoa from other mammalian species including those of human, rabbit, rat, and guinea pig. However, none were shown to cross-react with mouse lymphocytes. Two-thirds of the generated monoclonal antibodies can also bind live mouse spermatozoa. By an immunohistochemical technique using testicular sections, some of these monoclonal antibodies were shown to react with specific antigens expressed during different stages of spermatogenesis. It is concluded that these mouse sperm isoantigens are sperm-specific and appear uniquely during spermatogenesis. Monoclonal isoantibodies produced in the present study may have potential applications regarding the investigations of sperm iso- or autoimmunity, spermatogenesis, and fertility control.

SUMMARYTwenty recombinant influenza virus strains bearing HSwl N I, H I N I or H3N2 surface antigens, together with their respective wild-type or laboratory-propagated parent viruses, were inoculated into 2 day-old infant rats and their replication in the turbinates and lungs of these animals observed over a period of 5 days. In addition, the ability of each of the recombinant and parent viruses to enhance a subsequent infection of these infant rats by Haemophilus influenzae type b was determined. The results showed that both parent and recombinant viruses replicated less well in the lungs than in the turbinates of infant rats, but the titres in both tissues were generally lower for the recombinant strains. The capacity of the majority of the recombinant influenza viruses to promote bacterial infection of the infant rats, as determined by the incidence of H. influenzae bacteraemia and meningitis, was also markedly less than that of their parent viruses. A correlation between virulence for man and both the replication in infant rat turbinates and the ability to enhance H. influenzae infection, was established for the virus strains studied. The data are discussed in relationship to the value of the infant rat-H, influenzae system as a laboratory marker for the determination of the virulence of influenza virus strains.

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We examined the in vitro susceptibilities of three reference strains and 41 recent clinical isolates of herpes simplex virus types 1 and 2 to 5-ethyl-2'-deoxyuridine. This thymidine analog exerts a type 2-preferential