Summary of clinical trials of inactivated influenza vaccine - 1978.

This report summarizes the clinical trials of the A/USSR/77 (H1N1) influenza vaccines performed in 1978. A total of 2,091 subjects participated in these trials. The results of these clinical trials indicated that two doses of H1N1 viral antigen were necessary to produce serum titers of hemagglutinin-inhibiting (HAI) antibody of greater than 1:40 in 80% or more of the test subjects younger than 25 years of age, who were unlikely to have experienced natural infection during the earlier period of prevalence of H1N1 virus (1947-1957).

Epidemic typhus in the United States associated with flying squirrels.

Between July 1977 and January 1980, seven cases of sporadic, nonepidemic "epidemic" typhus (Rickettsia prowazekii) were discovered in Virginia, West Virginia, and North Carolina. The reservoir seemed to be the southern flying squirrel (Glaucomys volans), an animal indigenous to the eastern United States; however, the vector or mode of acquisition was not evident. Diagnosis was established principally through complement fixation, indirect immunofluorescence, and toxin neutralization tests.

Experimental infection of ectoparasitic arthropods with Rickettsia prowazekii (GvF-16 strain) and transmission to flying squirrels.

Epizootiologic studies conducted during the past few years showed the existence of widespread natural infection of the southern flying squirrel, Glaucomys volans, with epidemic typhus rickettsiae, Rickettsia prowazekii. The ecological findings strongly implicated transmission of the etiologic agent by an arthropod vector. Studies were conducted under controlled laboratory conditions to determine whether ectoparasites naturally associated with flying squirrels (squirrel fleas, lice, mites and ticks) were capable of acquiring, maintaining and transmitting the infection.

Further studies of the neuraminidase content of inactivated influenza vaccines and the neuraminidase antibody responses after vaccination of immunologically primed and unprimed populations.

Purified concentrates of influenza A/USSR/90/77(H1N1)-like, A/Texas/1/77 (H3N2)-like, and B/Hong Kong/5/72-like viruses used for preparation of investigational and licensed vaccines in 1978 to 1979 were tested for their content of neuraminidase enzyme activity. Concentrates of H1N1 virus used to prepare vaccines for clinical investigations performed in the spring of 1978 had neuraminidase activity at that time which decreased during storage to almost undetectable levels (three lots) or by 50% (one lot) by the winter of 1978. Several other lots of concentrates prepared with H1N1 virus and used for vaccine formulation had no detectable neuraminidase enzyme activity when tested in the winter of 1978, at a time when they would be administered in vaccines.

The rickettsia-like organisms TATLOCK (1943) and HEBA (1959): bacteria phenotypically similar to but genetically distinct from Legionella pneumophila and the WIGA bacterium.

Two "rickettsia-like organisms," TATLOCK and HEBA, isolated from human blood via guinea pigs and embryonated eggs in 1943 and 1959, respectively, have been cultured on artificial media (charcoal yeast extract agar) for the first time and characterized. TATLOCK and HEBA have identical cultural, biochemical, and antigenic characteristics, as well as identical cellular fatty-acid composition and antimicrobial susceptibilities. These two bacteria have most of the cultural and biochemical characteristics of Legionella pneumophilia, and their gas-liquid chromatography cellular fatty-acid profile is similar to that of WIGA, another bacterium similar to L.