ICOARACI, A NEW VIRUS RELATED TO NAPLES PHLEBOTOMUS FEVER VIRUS.
Explore the source record for details and available documents.
Biomedical subjects
Publications and source records attributed to R E SHOPE.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Hemophilus pleuropneumoniae, the causative agent of porcine contagious pleuropneumonia (PCP) is an encapsulated organism that has the metabolic features of the parainfluenza group of Hemophilus in that it requires DPN but not hemin for growth. Its formation of nitrate reductase cytochrome a(1) and non-physiologically reducible cytochrome c(1) in the stationary phase, together with its requirement of electron transport through oxidases for growth are typical of non-hemin-requiring Hemophilus species. It has the closest genetic homology, judged from the capacity of its DNA to induce transformation to streptomycin resistance, with H. parasuis but can be differentiated from this organism on the basis of its growth in defined medium and its marked and characteristic pathogenicity for swine.
An acute frequently rapidly fatal respiratory illness occurring as an epidemic disease in Argentine swine has been shown to have a bacterium of the genus Hemophilus as its causative agent. This organism, for which the name Hemophilus pleuropneumoniae is suggested, causes a singular, fulminating pleuropneumonia in experimental swine. The very marked effectiveness of H. pleuropneumoniae as a respiratory pathogen contrasts strikingly with the relatively mild pathogenicity of the well known swine Hemophilus, H. influenzae suis, which, in concert with a virus, causes a less highly fatal respiratory ailment, swine influenza. Porcine contagious pleuropneumonia (PCP) is contagious under experimental conditions. In the pathogenesis of the disease, histopathological studies of early cases suggest that the lymphatics of the lung and pleura may be primarily involved and that the pneumonia and pleuritis then proceed from these initial sites of reaction.
Hemophilus pleuropneumoniae is highly pathogenic for swine when given intranasally. As few as 100 organisms induce characteristic porcine contagious pleuropneumonia (PCP) and, when as many as one-half million are given, the infection usually proceeds to a fatal termination. While the organism is highly pathogenic when introduced by way of the respiratory tract, it is innocuous when given subcutaneously even in large numbers. Swine that have been inoculated subcutaneously are rendered solidly immune to infection with H. pleuropneumoniae intranasally. The marked pathogenicity of H. pleuropneumoniae for swine has been contrasted with the lack of pathogenicity of another swine Hemophilus, H. influenzae suis. It has been pointed out that, in its high degree of pathogenicity, in its pneumotropism, and in its immunogenicity by a non-respiratory route of inoculation, H. pleuropneumoniae appears to resemble certain viruses more than it does a bacterium.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Serial passage through the brains of newborn mice markedly attenuates the New Jersey strain of EHD virus. Deer inoculated with this attenuated virus show no clinical evidence of illness, but do develop virus-neutralizing antibodies in their sera. They also become solidly immune to infection with the regularly fatal unattenuated virus.
Explore the source record for details and available documents.
The New Jersey strain of EHD virus has been propagated in newborn Swiss mice by the intracerebral route and is regularly lethal beyond the first serial mouse passage. A complement-fixing antigen prepared from the brains of infected mice reacts positively with the sera of deer recovered from infection with either the New Jersey or South Dakota strain of virus, but not with the serum of normal deer. The mouse-passaged virus induced an inapparent infection in an experimental deer. The virus can also be grown serially in HeLa cell culture and induces a characteristic cytopathic effect. It is neutralizable in such cultures to high titer by the sera of deer recovered from EHD (New Jersey strain) and to lower titer by the serum of a deer recovered from EHD (South Dakota strain). Normal deer serum does not neutralize the virus in tissue culture. The HeLa cell-passaged virus induced typical lethal EHD in an experimental deer and virus could be recovered from most of the tissues of this animal in HeLa cell culture. An unexplained prozone of inhibition of cytopathogenicity at low dilutions was observed in cultures of some of the organs. The fact that EHD virus exhibited a limited sensitivity to sodium desoxycholate suggests that it may belong in the arbor virus group.
Three tumors initiated by well characterized viruses, but in which virus is not detectable by ordinary virological techniques, are discussed. The question of the possible state of the virus within these seemingly non-infectious tumors is considered, largely from the standpoint of findings with the rabbit papilloma virus. This agent in its natural host, the cottontail rabbit, is infective, can be seen as virus bodies with the electron microscope, and can be visualized with fluorescent antibody only in the upper keratinizing cells of individual papillomas. At the growing bases of such papillomas, where neoplasia is in active progress, no infective virus is demonstrable and viral bodies cannot be visualized by either the electron microscope or fluorescent antibody. A hypothesis is presented that rabbit papilloma virus exists in cottontail papillomas in two forms-one, the complete mature virus, composed of nucleic acid and protein, and the other, immature virus, composed of naked viral nucleic acid without its protein coating. The function of the mature papilloma virus is to initiate tumor formation,-that of the immature virus, to maintain neoplasia. In the non-infective domestic rabbit papilloma, the viral nucleic acid and protein fail to combine to form mature infective virus and, as in the cottontail papilloma, neoplasia is maintained by the activity of the viral nucleic acid alone.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.