Robert M. Chanock

A 27-nm particle was observed by immune electron microscopy in an infectious stool filtrate derived from an outbreak in Norwalk, Ohio, of acute infectious nonbacterial gastroenteritis. Both experimentally and naturally infected individuals developed serological evidence of infection; this along with other evidence suggested that the particle was the etiological agent of Norwalk gastroenteritis.

logic study of altered clinical reactivity to respiratory syncytial (RS) virus infection in children previously vaccinated with an inactivated RS virus vaccine. Amer. J. Epid., 1969,89: 405-421.—A formalin inactivated monkey kidney culture propagated 100-fold concentrated respiratory syncytial (RS) virus vaccine was administered intramuscularly to residents of Harrison and Arthur Cottages in Junior Village, a District of Columbia Welfare Institution for homeless but otherwise normal infants and children. No significant local or systemic vaccine reactions were observed. One to three doses of vaccine v/ere found to produce CF antibody titers of 1:8 to 1:256 in 27 (97%) of 28 seronegative (<1:4) residents; the vaccine also stimulated high levels of neutralizing antibody. A sharp outbreak of RS virus infection occurred approximately 9 months after the vaccine study was initiated; RS virus was recovered from 60 (41%) of 146 residents and serologic evidence of infection was detected in 37 (92%) of 40 seronegative individuals. Recovery of RS virus was found to be significantly associated not only with the onset of febrile illness but also with the onset of febrile pneumonia illness. The vaccine not only

Recent volunteer and controlled epidemiologic field studies have provided evidence which firmly associates the agent first recovered by Eaton in 1944 with lower respiratory tract illness of man.1-3 A serologic response to the Eaton agent occurs in approximately 90 per cent of pneumonia illnesses in which cold agglutinins develop during convalescence as well as in a significant but variable proportion of cold agglutinin-negative pneumonias.2 4 The development of pneumonia and other forms of respiratory disease following the administration of tissue culture-grown Eaton agent to volunteers and the demonstration that naturally acquired antibody offered protection against such illness supports the contention that the agent is a respiratory tract pathogen.5 For many years, the agent was tentatively classified as a virus. The large size of the agent (180-250 m,i) and its sensitivity to streptomycin and various tetracycline derivatives, however, posed some difficulty with such a classification.6-8 Recently, Marmion and Goodburn were able to visualize small cocco-bacillary bodies on the mucous layer covering the bronchial epithelium of the Eaton agent infected chick embryo.9 The distribution of these bodies corresponded with the localization of Eaton agent as visualized by the fluorescent antibody technique. These workers also demonstrated that the Eaton agent was inhibited by an organic gold salt. Clyde visualized extracellular colony-like structures in stained preparations of infected tissue culture; these structures corresponded with the areas of specific immunofluorescence.U? Both groups of workers suggested the possibility that the Eaton agent may be a pleuropneumonia-like (PPLO) rather than a virus. Cultivation of the organism in cell-free media, however, was not achieved. T