SARKAR, J. K.; MITRA, A. C.
Indian Journal of Medical Research
75 strains of variola virus were isolated from patients suffering from smallpox in Calcutta-25 from haemorrhagic, 25 from confluent and 25 from discrete infection. The virulence of the strains was tested by 4 methods: (A) mortality of chick embryos and (B) virus content of chick-embryo livers after a standard dose of virus, (C) the severity of the histological reaction of chorioallantoic membranes infected with variola virus and (D) the mortality of baby mice given a standard dose of virus intraperitoneally. There was a correlation between the results and the clinical type of disease 12 of 25 strains 'from patients with haemorrhagic infection were positive in all 4 tests, 9 of 25 from patients with confluent infection and 0 of 25 from patients with discrete infection. Analysis showed that when the results of the 4 tests were considered together the difference between the number of virulent strains in each group was significant at the 1% level.
Although they were able to demonstrate a close relationship between virulence of virus strain and the clinical: severity of the disease, the authors believe that other factors also influence the clinical severity, especially the immune response of the patient.
The virus strains of least virulence were shown to be variola major and not alastrim. Colin Kaplan.
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Organism descriptor(s) :
man, mice, variola virus, viruses
chick embryos, embryos, histology, human diseases, immune response, infectious diseases, liver, mortality, smallpox, strains, virulence
alastrim, communicable diseases, death rate, immunity reactions, immunological reactions, milk pox
Broader term(s) :
Homo, Hominidae, primates, mammals, vertebrates, Chordata, animals, eukaryotes, Muridae, rodents, Orthopoxvirus, Chordopoxvirinae, Poxviridae, dsDNA Viruses, DNA Viruses, viruses