Observations on Natural and Laboratory Infection of Rodents with the Etiologic Agent of Korean Hemorrhagic Fever

Abstract

Studies were conducted to define the natural host range of the Korean henorrhagic fever (KHF) agent in South Korea, and to identify colonized rodents susceptibl64o this infection. Eight species of field rodents were captured in areas of Korea endemic for yKHF and their tissues were examined by immunofluorescence for the presence of KHF antigen. One hundred and fourteen of 817 Apodemus agrarius coreae captured between 1974 and 1978 had one or more positive organs. No positive organ was found in 239 rodents of the other seven species examined. Two hundred and thirty-eight specimens of Apodemus agrarius Ck jejuensis captured on Jeju Island, an area thought to be free of disease, were also negative. Attempted laboratory infection of nine species of rodents captured in the field but maintained in the laboratory was successful only in the two subspecies of Apodemus. The 46 specimens of A. a. jejuensis tested in this manner were all uniformly susceptible to infection as determined by immunofluorescence. Serial sacrifice of experimentally infected A. a. jejuensis revealed viremia of short duration terminating on day 10 postinfection. In contrast, other tissues of this animal, including lung, kidney, liver and parotid gland were positive on day 10 and remained so through the 100-day observation period. When 12 species of colonized laboratory rodents were inoculated with KHF agent five were found to develop KHF antibody by indirect immunofluorescence and two, Calomys callosus and Apodemus agrarius ningpoensis, developed detectable KHF antigen in their tissues. The first successful isolation and propagation demic areas of disease on the Korean peninsula, LA.) of the etiologic agent of Korean hemorrhagic fever was demonstrated utilizing the indirect fluores-... i (KHF) was described in a previous communicacent antibody (IFA) technique and human KHF 1 tion. The presence of KHF agent-specific antigen convalescent sera. Numerous isolations of the in frozen sections of various tissues of Apodemus agent have been made from rodents of this agrarius coreae, a vesper mouse indigenous to en-species, and successive passage of the agent in a boow-on_ subspecies, Apodemus agrarius jejuensis captured in areas free of natural disease, has been report

Accumulation of Terminally Deleted RNAs May Play a Role in Seoul Virus Persistence

“…Culture supernatant was harvested for virus assay, and infected cells were harvested for RNA isolation at 6, 7, 9, 12, 16, 26, and 46 days p.i. for infection 1 and at 2,4,6,7,9,12,16,26,36,46,56,68,88,109, and 139 days p.i. for infection 2.…”

“…(4,12,16,17,19,40). During persistence, the levels of infectious virus or antigen-positive cells are generally lower, and in some tissues or secretions may vary or disappear and reappear several times during the course of the study in a wave-like pattern (4,12,16,17,18,38,40). Thus, while virus and/or antigen can be detected in many tissues and bodily fluids during the acute stage, they are often only detected sporadically from the same sites during persistence.…”

Do Unusual Site-Specific Population Dynamics of Rodent Reservoirs Provide Clues to the Natural History of Hantaviruses?

“…In the specific host, hantaviruses establish a chronic infection that involves persistent or sporadic shedding of infectious virus in bodily secretions and excretions for many months, probably for the life of the host (Lee et al, 1981;Yanagihara, 1990;Hutchinson et al, 1998). Numerous studies have demonstrated an age-related prevalence of antibody, often favoring males (Glass et al, 1988;Childs et al, 1994;Mills et al, 1997;Calisher et al, 1999), indicating that virus is maintained in reservoir populations via horizontal transmission, perhaps most frequently through aggressive encounters among adult males.…”

Role of Maternal Antibody in Natural Infection of Peromyscus maniculatus with Sin Nombre Virus

“…Unlike other members of the family Bunyaviridae, hantaviruses are not arthropod borne but are believed to be transmitted to humans from their rodent hosts by inhalation of aerosolized rodent excrement (15). The mode of SNV transmission between deer mice is unclear, but field studies have provided indirect evidence of horizontal transmission of SNV among rodents via biting and other aggressive behavioral interactions (2,4,18,19).…”

“…Although rodents infected with hantaviruses do mount a strong humoral immune response, and antibody is able to neutralize virus when assayed in vitro, data obtained from laboratory and field studies of both Old World and New World hantaviruses indicate that animals remain systemically and chronically infected (12,15,22,28).…”