Ever since arbovirus infections became known and their relative importance assessed, experiments were designed to elucidate the mode of transmission and the most important natural hosts responsible for perpetuating the infection in nature. Human infections and the disease in wild rodents, birds, and domestic animals were studied in relation to viremia and distribution of the infectious agent in the organism. With increasing epidemiological studies it became apparent that the neural manifestations of the disease are very uncommon, confined only to a small percentage of individuals of the most...

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Springer Book Archives

The expression of many bacterial genes adapts itself in an almost in- stantaneous and reversible way to specific environmental changes. More specifically, the concentration of a number of metabolites, a function of the amounts of enzymes involved in their synthesis or degradation, in turn retroacts on the rate of synthesis of these enzymes. The genetic bases for this regulation were established by JACOB and MONOD (1961). These authors also showed how the known elements of these regulatory mechanisms could be connected into a wide variety of circuits endowed with any desired degree of...

Phenomena as diverse as tuberculin sensitivity, delayed sensitivity to soluble proteins other than tuberculin, contact allergy, homograft rejection, experimental autoallergies, and the response to many microorganisms, have been classified as members of the class of immune reactions known as delayed or cellular hypersensitivity. Similarities in time course, histology, and absence of detectable circulating immunoglobulins characterize these cell-mediated immune reactions in vivo. The state of delayed or cellular hypersensitivity can be transferred from one animal to another by means of...

Influenza continues to be one of the major epidemic diseases of man and is, in fact, his only remaining pandemic disease (BEVERIDGE, 1969). This is largely because influenza virus undergoes extreme antigenic variation, the mechanism of which is still poorly understood. Two kinds of antigenic variation occur in influenza viruses, antigenic drift and major antigenic shifts; both involve chan- ges in the hemagglutinin and neuraminidase antigens on the surface of the virus. Antigenic drift, which involves gradual changes in the surface antigens of influenza virus, is thought to result from the...

Springer Book Archives

Springer Book Archives

Springer Book Archives

Prominent progress in molecular biology was only made when it became possible to separate functionally distinct molecules by taking advantage of their biophysical properties. Likewise, the analysis of the functions of hetero- geneous populations of immunocompetent cells, as to the functional properties of their various subpopulations, can not be done until these can be isolated in reasonably pure form by selective fractionation. During the last few years significant advances have been made in this field, and cells have been separated according to size, density or charge (MILLER et aI., 1969;...