RESUMEN
A variant of variola virus is described which produces a late polypeptide of 25 kDa instead of one of 27 kDa and which has an additional endonuclease cleavage site for SalI in the viral DNA. These markers were shown to be genetically independent and to characterize 14 of the 48 variola strains which were examined. The variant strains were isolated from smallpox outbreaks originating in or from Pakistan between 1961 and 1974 and also from two cases at a Mission Hospital in Vellore, India in 1964. No variant strains were found among 9 other isolates from cases of variola major occurring in other parts of India or in Bangladesh, nor among 4 isolates from Indonesia, 15 from Africa or 6 isolates of variola minor.
Asunto(s)
Desoxirribonucleasas de Localización Especificada Tipo II/metabolismo , Variación Genética , Viruela/virología , Virus de la Viruela/clasificación , Virus de la Viruela/genética , Proteínas Virales/química , Animales , ADN Viral/genética , ADN Viral/metabolismo , Humanos , India/epidemiología , Pakistán/epidemiología , Viruela/epidemiología , Virus de la Viruela/aislamiento & purificaciónRESUMEN
The thymidine kinase produced in cell cultures by several orthopoxviruses has been tested for sensitivity to inhibition by thymidine triphosphate (TTP). Thymidine kinase preparations from eleven variola isolates and from five "whitepox" isolates were all found to be sensitive to inhibition by TTP. Preparations from other orthopoxviruses, including vaccinia, cowpox, and monkeypox, were all resistant to inhibition by TTP. There was no overlap between the two groups of results and no viruses were found which gave intermediate results. Tests with hybrid viruses showed that this character segregated independently of other biological marker characters and is thus a valuable additional marker for variola and variola-related viruses.
