U. S. Department of Health, Education and Welfare, Public Health Service, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Middle America Research Unit, Balboa Heights, Canal Zone
Certain properties of Machupo virus are reported. These include presence of RNA, pH stability in the range of 6.0 to 9.0, rapid thermal inactivation at temperatures of 25°C and higher, and more effective stabilization of infectivity titers after prolonged storage (1 year) at -70°C in media containing protein supplements.
Parenteral inoculation of infant hamsters and mice with Machupo virus resulted in observable illness and death, or both, the LD50 and ID50 being roughly comparable. Inapparent infection in adult animals was detected by the presence of CF and N antibody. A variety of domestic and wild animals proved to be either resistant to the virus or susceptible only in a clinically inapparent manner. The Central American marmoset, Saguinus geoffroyi, was found to be a clinically susceptible animal. Illness and death occurred after administration of virus subcutaneously or by scarification.
Present address: The Rockefeller Foundation, Bogotá, Colombia.