R. Yanagihara

Experimental infection of human vascular endothelial cells by pathogenic and nonpathogenic hantaviruses

SummaryTo investigate whether the hantaviruses replicate in endothelial cells, we inoculated human umbilical vein endothelial cells with several pathogenic and nonpathogenic strains of hantavirus. Intracytoplasmic, virus-specific granular fluorescence was detected initially at three days postinoculation and nearly 100% of cells contained viral antigen at 10 days. Cytopathic effect or inclusion bodies were not observed. The in vitro demonstration of the susceptibility of endothelial cells to hantaviruses corroborates in vivo findings, and suggests that endothelial cells may serve as target cells in hemorrhagic fever with renal syndrome.

Differential susceptibility and resistance of immunocompetent and immunodeficient mice to fatal Hantaan virus infection

SummarySusceptibility and resistance to fatal Hantaan virus meningoencephalitis were studied in immunocompetent (nu/+) and congenitally T-cell deficient (nu/nu) CD-1 mice of different ages. Susceptibility of nu/+ mice to fatal infection was age-dependent, as evidenced by 100 percent mortality in mice inoculated intracerebrally with Hantaan virus (strain 76–118) during the first week of life, 60 percent mortality in mice inoculated at 9 days of age, and no disease or death in mice inoculated at 14 to 42 days of age. Deaths occurred significantly earlier in nu/+ mice inoculated at 5 and 7 days of age than in nu/+ mice less than 24 hours old. Nu/nu littermates of the same age did not exhibit a similar inverse relationship between age and survival times. Moreover, nu/nu mice 14 days or older remained susceptible, albeit with delayed onset of illness and time of death. Virus titers in brain tissues of nu/+ mice inoculated at 7 days and of nu/nu nice inoculated at 7, 9 and 14 days of age were nearly identical. In older nu/+ mice, peak virus titers were comparatively lower, but they did not seem to be influenced by the magnitude of the neutralizing antibody response. The more rapidly fatal course in nu/+ mice inoculated at a week of age than at birth, and the differential resistance between weanling nu/+ and nu/nu mice to Hantaan virus meningoencephalitis suggest that cell-mediated immunity may be responsible for both enhancement of disease and recovery from infection.

White matter ultrastructural pathology of experimental Creutzfeldt-Jakob disease in mice.

SummaryCreutzfeldt-Jakob disease (CJD), previously regarded as a neurodegenerative disorder strictly of the gray matter, occasionally occurs as a panencephalopathic form which is characterized by severe white matter damage. An ultrastructural study of the white matter pathology in mice experimentally infected with the Fujisaki strain of CJD virus revealed: (1) vacuoles within myelin sheaths, formed by splitting either at the major dense or intraperiod lines, or within axons; (2) macrophages filled with numerous myelin figures, lipid droplets and paracrystalline inclusions; (3) astrocytes actively digesting myelin debris; (4) unusual wrapping of several axons by a common myelin sheath; (5) vesicular degeneration of myelin sheaths; (6) close contact between numerous coated pits and outer myelin lamellae; and (7) proliferation of inner mesaxons. Our data indicate that the damage to myelinated axons in the panencephalopathic type of CJD is accomplished primarily by active degradation of myelin by macrophages and astrocytes and by formation of intra-axonal and intra-myelin vacuoles. The myelin vacuolation is most consistent with that produced by leukolysins released from activated macrophages and astrocytes.

Serological survey of Prospect Hill virus infection in indigenous wild rodents in the USA

We found serological evidence of infection with Prospect Hill virus, a Hantaan-like virus isolated from meadow voles (Microtus pennsylvanicus), in microtine and cricetid rodents trapped in Maryland, West Virginia, Minnesota and California, USA. Fluorescent antibodies were detected in sera from M. pennsylvanicus (74/277), M. californicus (39/185), Clethrionomys gapperi (5/51), Peromyscus maniculatus (4/22) and P. truei (1/11). Sera from seropositive P. maniculatus contained neutralizing antibodies against Prospect Hill virus, confirming that infection with Prospect Hill virus or antigenically related viruses is not restricted to microtine rodents in the USA. Despite the widespread distribution of Prospect Hill virus in indigenous rodents, the recent demonstration that American mammalogists are only rarely infected supports the view that the overall risk of Prospect Hill virus infection in man is low.

Genetic and phylogenetic analyses of hantaviral sequences amplified from archival tissues of deer mice (Peromyscus maniculatus nubiterrae) captured in the eastern United States

SummaryThe S and M segments of a hantavirus, enzymatically amplified from tissues of Cloudland deer mice (Peromyscus maniculatus nubiterrae) captured during 1985 in West Virginia, diverged from strains of Four Corners virus from the southwestern United States by more than 16% and 6% at the nucleotide and amino acid levels, respectively. Phylogenetic analysis suggested that this virus strain (designated Monogahela) forms a possible evolutionary link between the Four Corners and New York hantaviruses.

Localization of amyloidogenic proteins and sulfated glycosaminoglycans in nontransmissible and transmissible cerebral amyloidoses

SummaryWe report the localization of amyloid β-protein and sulfated glycosaminoglycans in senile plaques and vascular amyloid deposits in brain tissues from patients with Downs syndrome and Alzheimers discase, and in neurofibrillary tangles of these diseases and those of Guamanian parkinsonism-dementia and amyotrophic lateral sclerosis. We also report the immunolocalization of scrapie amyloid in amyloid plaques containing glycosaminoglycans in kuru, Creutzfeldt-Jakob disease, and Gerstmann-Sträusslers syndrome. Thus, amyloidogenic proteins and sulfated glycosaminoglycans may be copolymerized in amyloid deposits in the nontransmissible and transmissible cerebral amyloidoses.

Hemorrhagic fever with renal syndrome in Yugoslavia: epidemiologic and epizootiologic features of a nationwide outbreak in 1989.

A nationwide epidemic of hemorrhagic fever with renal syndrome (HFRS) occurred in Yugoslavia in 1989. Sera from 609 hospitalized patients, from all six Republics (Bosnia and Hercegovina, Croatia, Macedonia, Montenegro Serbia, Slovenia) and two Provinces (Kosovo and Vojvodina), who had signs and symptoms suggestive of HFRS, and sera and lung tissues from 544 small mammals belonging to 13 species were studied for evidence of hantavirus infection. Of the 226 patients with serologically confirmed HFRS, 182 resided in Bosnia and Hercegovina or in Serbia. The severity of disease differed from region to region, with an overall fatality of 6.6% (15/226). Patients from southern Yugoslavia tended to have more severe disease and exhibited two types of antibody patterns, while approximately equal numbers of clinically severe and mild cases of HFRS were registered in central Yugoslavia, where four types of antibody patterns were found. Two of these antibody patterns suggested the existence of hantaviruses which are antigenically distinct from those reported to date. Two seasonal peaks of disease, one during the summer and the other in late autumn, were found. Hantaviral antibodies and/or antigens were detected most often in the yellow-necked mouse (Apodemus flavicollis) (88/189), the wood mouse (Apodemus sylvaticus) (28/146), the striped field mouse (Apodemus agrarius) (10/64), the bank vole (Clethrionomys glareolus) (36/63), the house mouse (Mus musculus) (14/29), and the Norway rat (Rattus norvegicus) (14/21). Five other species of rodents and insectivores were infrequently infected.

Appearance of tubulovesicular structures in experimental Creutzfeldt-Jakob disease and scrapie preceeds the onset of clinical disease

SummaryWe have consistently observed tubulovesicular structures in brain tissues during the terminal stages of naturally occurring and experimentally induced spongiform encephalopathies, irrespective of the host species and virus strain. In NIH Swiss mice inoculated intracerebrally or intraocularly with the Fujisaki strain of Creutzfeldt-Jakob disease (CJD) virus, tubulovesicular structures, measuring 20–50 nm in diameter, were particularly prominent in dilated, pre-and postsynaptic neuronal processes, occasionally being mixed with synaptic vesicles. These structures appeared 13 weeks following intracerebral inoculation, 5 weeks before the onset of clinical signs, when spongiform changes were also detected. The number and density of tubulovesicular structures increased steadily during the course of clinical disease, and were particularly abundant in mice 47 to 51 weeks after intraocular inoculation. In hamsters infected with the 263 K strain of scrapie virus, these structures were initially detected 3 weeks following intracerebral inoculation and increased dramatically at 10 weeks postinoculation. The appearance of tubulovesicular structures before the onset of overt disease in mice inoculated with CJD virus by either the intracerebral or intraocular route, and before the appearance of other neuropathological changes in hamsters infected with scrapie virus, indicate that they represent either a part or aggregate of the infectious virus or a pathological product of the infection.

Experimental hantavirus infection in nonhuman primates

SummaryMild, transient proteinuria and azotemia were produced in three cynomolgus monkeys (Macaca fascicularis) and a chimpanzee (Pan troglodytes) following intravenous inoculation with Prospect Hill virus, a hantavirus isolated from meadow voles in the United States. This is the first demonstration of an acute nephropathy in nonhuman primates with the viruses causing hemorrhagic fever with renal syndrome.

Pathogenesis of experimental Hantaan virus infection in laboratory rats.

SummaryWeanling Fischer rats inoculated intramuscularly with Hantaan virus (strain 76–118) developed subclinical infections characterized by transient viremia and shedding of virus in saliva, persistence of virus in lung, pancreas, spleen and liver, and development of fluorescent and neutralizing antibodies in serum with immune complex deposition in lung. Viremia and virus shedding in saliva occurred 10 to 13 days after inoculation. Horizontal intracage transmission of infection occurred between 35 and 63 days post-inoculation, long after disappearance of virus in oropharyngeal secretions and blood. Multiple attempts to demonstrate infectious virus in feces and urine during this period were unsuccessful. The inability to detect virus in urine samples of experimentally infected rats may have resulted from intermittent or low-titered viruria. This contrasts sharply with the prolonged high-titered viruria reported in striped field mice(Apodemus agrarius) infected with Hantaan virus, suggesting differences in the mode(s) of virus transmission in nature.