To learn if Chlamydia trachomatis causes in young infants a distinctive penumonia characterized by chronic, afebrile course, diffuse lung involvement and elevated serum immunoglobulins G and M, 47 black infants four to 24 weeks of age were examined for nasopharyngeal shedding of C. trachomatis and serum immunofluorescent antibody to lymphogranuloma venereum Type I. Nasopharyngeal C. trachomatis was found in 18 of 20 with the pneumonia syndrome, two of 15 with various other illnesses and 10 of 12 with inclusion conjunctivitis but without lower respiratory illness. Chlamydial antibody titers of infants with the pneumonia syndrome were significantly elevated (geometric mean-1, pneumonia vs. conjunctivitis = 24,833 vs. 1024 P less than 0.001). No other commonly recognized respiratory pathogens were consistently associated with the pneumonia syndrome. We believe these findings demonstrate an association between the distinctive pneumonia syndrome and C. trachomatis. This, in turn, is a particular facet of a more general event consisting of frequent colonization of the respiratory tract by C. trachomatis in natally acquired infection.

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A multiplicity-dependent interference was observed in respiratory syncytial virus preparations (Randall strain) grown in HEp-2 cells, and the factor mediating this interference was characterized. Cloned virus did not demonstrate this multiplicity-dependent interference, but its replication was shown to be inhibited by the interfering factor by assays of reduction of infectious yield assay, the interferon factor was found to be particulate, to be inactivated by UV irradiation, and not to interfere with the replication of a heterologous virus, vesicular stomatitis virus. These characteristics are compatible with the physical properties and biological behavior of defective interfering particles. Defective interfering particles were generated by four undiluted passages of cloned virus but were not apparent after eight passages at a multiplicity of infection of 0.1.

Hamre, D. and M. Beem (DepL Pediatrics, Univ. of Chicago, Chicago, 111. 60637). Virologic studies of acute respiratory disease in young adults. V. Coronavirus 229E infections during six years of surveillance. Am J Epidemiol 96: 94-106, 1972.-In a surveillance study of acute respiratory disease in medical students that spanned six consecutive seasons between 1961 and 1968 and encompassed 937 student years of observation, infection with coronavirus 229E was identified by virus isolation and serologic studies. Virus isolation identified 12 infections, 8 in one season, 4 in another. Complement fixing (CJF) antibody titer rises identified 133 infections that occurred in all six seasons of surveillance, involving from 15to 35% of students in three seasons of "high" prevalence, and 1 to 5% in intervening seasons of "low" prevalence. Infection occurred in a winter-spring seasonal pattern and was associated with acute respiratory illness that was not clinically distinctive. Neutralizing antibody to 229E was commonly present in the sera of the students. The level of this did not appear to influence the occurrence of, or likelihood of illness with, reinfection as judged by CF seroconversion; however, the frequency of significant rise in neutralizing antibody titer with reinfection was inversely related to pre-infection levels of this antibody. Infection with other common respiratory viruses did not stimulate significant CF or neutralizing antibody titer rises to 229E. coronaviruses; respiratory tract infections; serology; viruses

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