Dorland J. Davis

Primary isolation of influenza A, B, and C viruses in monkey kidney tissue cultures.

Summary 1. Influenza virus isolations were attempted simultaneously in monkey kidney tissue cultures and 11-day embryonated eggs from 78 throat samples taken during the 1955 epidemic in the Washington, D.C. area. Higher percentage of influenza B isolations was made in monkey kidney tissue cultures (21.8%) than in embryonated eggs (1.3%). Influenza C and Type 3 APC viruses were also recovered in the monkey kidney tissue cultures from some of these samples. Influenza A virus and influenza C virus were also isolated in monkey kidney cultures from other samples, but whether this method offers a better medium than the usual embryonated eggs was not determined for these types. 2. Cytopathogenic changes in monkey kidney cultures produced by influenza A, B, and C viruses appeared to be similar. These changes were readily recognized, and were associated with the production of hemagglutinins. 3. The use of monkey kidney cultures offered distinct advantages over chick embryos: (a) current strains of influenza B virus could be more readily isolated, (b) the time required for isolation and identification of the virus was shortened and (c) other respiratory tract viruses such as the Type 3 APC virus could be isolated.

Recovery of psittacosis virus from chicks hatched from inoculated eggs.

Summary The data here presented indicates that chicks will hatch from eggs which have been infected with M. psittaci during the course of embryonic development and will survive in apparently good condition while harboring the virus in the organs for at least 22 days after hatching. While these experiments do not furnish evidence for the congenital transmission of the virus in the chicken, it is possible that in a more susceptible species the virus could be carried more effectively through the developmental and hatching period after either experimental or congenital infection.

Susceptibility of the English Sparrow (Passer domesticus) to Infection with Psittacosis Virus of Pigeon Origin

Summary A serologically diagrosed case of psittacosis following exposure to a sick English sparrow and its droppings suggested an investigation of this species of bird as a carrier of psittacosis virus. 103 sparrows were examined for presence of active virus and serum from 59 of them were tested for complement fixing antibodies, but no evidence of natural infection was obtained. Four birds inoculated intracranially, 2 inoculated intraperitoneally and 7 of 15 inoculated by the oral-gastric route with psittacosis virus of pigeon origin became infected and virus was recovered from their organs.

Reactivation of serum neutralized influenza virus and failure of its use in primary isolation.

Summary 1. Inactivated viruses of 4 strains of influenza A and 2 strains of influenza B reactivated serum neutralized homologous virus with an increase in titer of 100 fold or more. The reaction is serologically strain specific. 2. The degree of reactivation is dependent on time of addition of inactivated virus to active virus-antiserum mixture. The threshold time after which reactivation could not be noted was about 8 hours for A/Va/1/53 and about 3 hours for B/Lee. 3. Addition of concentrated, heat-inactivated virus to samples from throats of persons ill with influenza-like illness during an influenza epidemic failed to increase the number of influenza virus isolations over the usual method.