Isolation and characterization of a human T cell leukemia virus type II from a hemophilia-A patient with pancytopenia.

Human T cell leukemia virus (HTLV) type I has been isolated from the cultured T cells of several patients with adult T cell leukemia (ATL) and has been etiologically linked to ATL. However, HTLV-type II has been isolated only once, from the T cells of a patient with a T cell variant of hairy-cell leukemia. We report here the isolation of HTLV-II-related virus from the cultured T cells of a hemophilia-A patient with pancytopenia. The T cell line (CM) grows in the absence of T cell growth factor. Cord blood T cells were rapidly transformed when co-cultivated with irradiated CM cells. Heterologous competition radioimmunoassays using purified HTLV-I p24 showed the expression of HTLV-IIMO-related protein in these cells. Electron microscopy of the CM cells showed the presence of intracellular and extracellular type C viral particles. Comparison of the proviral genome in the CM cell line and the prototype HTLV-IIMO-containing cell line (MO) by molecular hybridization with probes specific for HTLV-IIMO indicated that restriction cleavage sites were identical. The fresh peripheral blood leukocytes of the patient contained two complete copies of the proviral genome, despite the lack of HTLV-II p24 expression. The virus from the cell line CM is designated as HTLV-IICM to distinguish it from the original HTLV-IIMO isolate.

Human T-cell leukemia virus in lymphocytes of two hemophiliacs with the acquired immunodeficiency syndrome.

Fresh and cultured peripheral blood cells from two patients with hemophilia A and the acquired immunodeficiency syndrome were examined for markers of infection with human T-cell leukemia virus (HTLV) type 1. Neither patient had antibody to membrane antigens of HTLV-infected cells at the time of culture. Electron microscopy of peripheral blood cells from Patient 1 and cultured cells from Patient 2 showed type C retrovirus-like particles. Examination of peripheral blood lymphocytes showed other smaller virus-like particles in circulating mononuclear cells from both patients. Indirect immunofluorescence of peripheral mononuclear cells from both patients and of cultured cells from Patient 2 showed staining with antibodies to purified HTLV and to HTLV core proteins p24 and p19.

Lymphadenopathy associated virus infection of a blood donor--recipient pair with acquired immunodeficiency syndrome.

A retrovirus isolated from three patients with the acquired immunodeficiency syndrome (AIDS) in the United States was morphologically and antigenically identical to lymphadenopathy associated virus isolated in France. Two of these isolates were from a blood donor-recipient pair, each of whom developed AIDS. Lymphadenopathy associated virus was isolated from the blood donor's lymphocytes 12 months after his onset of AIDS symptoms and from the blood recipient's lymphocytes 1 month after her onset of AIDS symptoms. Two isolates from the blood donor-recipient pair and an isolate from an epidemiologically unrelated homosexual man were examined by competitive radioimmunoassay to determine their antigenic relatedness to each other and to other human retroviruses. The major core proteins (p25) of the isolates were antigenically identical and all three isolates were identical to prototype lymphadenopathy associated virus isolated in France.

Mode of entry of a neurotropic arbovirus into the central nervous system. Reinvestigation of an old controversy.

The mechanism by which neurotropic arboviruses gain access to the central nervous system remains uncertain, although it is generally assumed that viremic infection results in growth across or passive diffusion through brain capillaries. In contrast to the natural reservoir hosts of these arboviruses, clinical hosts (e.g., horses, humans) have viremias of very brief duration and low magnitude. We investigated the question of neuroinvasion in 5- to 6-week-old Syrian hamsters infected with St. Louis encephalitis virus (strain TBH-28). This model shares with the human disease low or undetectable viremia and many clinical and pathoanatomical features. The mortality rate after intraperitoneal inoculation of a moderate viral dose was 88%. No viremia was detectable by a sensitive assay in 31% of the animals. In the remaining hamsters, the mean peak viremia was 1.0 log10 plaque-forming units/0.05 ml and the mean duration 1 to 2 days. There was no correlation between viremia and outcome of infection, length of incubation period, or brain virus titer. Tissue infectivity studies showed a rise in titer in the olfactory neuroepithelium on day 4 postinoculation, then in the olfactory bulbs (day 5 postinoculation), and finally in the remainder of the brain (day 6 postinoculation). Specific immunofluorescence was demonstrated in the bipolar neurons of the olfactory epithelium, their dendrites, and in axon bundles of the olfactory nerves in the submucosa. By electron microscopy, virus particles and associated tubular structures were demonstrated within dendrites, perikarya, and axons of olfactory neurons, and to a lesser extent in macrophages and Bowman's gland cells in the lamina propria. In cells of Bowman's glands large numbers of virions were sequestered within secretory granules. Virus was recovered from nasal washings on day 4 postinoculation. Similar findings were obtained in weanling mice inoculated intraperitoneally with another (mouse-virulent) St. Louis encephalitis viral strain (77V-12908). These data taken together indicate that the olfactory pathway is the principal route of viral entry into the central nervous system. After peripheral inoculation a low-level viremia results in infection of highly susceptible cells in the olfactory neuroepithelium, allowing centripetal axonal transport of virus to the olfactory bulb, whence spread is unimpeded throughout the neuropil of the central nervous system. Infection of Bowman's gland cells in the olfactory mucosa and shedding of virus in nasal mucus may be an adaptation for nonarthropod-borne transmission, a feature of many flaviviruses.

Pathogenesis of rabies in dogs inoculated with an Ethiopian rabies virus strain. Immunofluorescence, histologic and ultrastructural studies of the central nervous system.

Dogs were inoculated with either an Ethiopian of Mexican rabies virus strain. The distribution of viral antigen and lesions were studied by immunofluorescence, histologic and electron microscopic techniques. In all dogs inoculated with the Ethiopian rabies virus strain, tremendous whorls of filamentous fluorescing aggregates were observed throughout the brain; these were not observed in dogs inoculated with the Mexican virus. Lesions consisted on neuronal degeneration and neuronophagia, associated with large inclusion bodies and widespread inflammation in dogs inoculated with the Ethiopian isolate. All observed portions of the brain and spinal cord were affected. In general, lesions were much less severe with Mexican isolate. Occasional astrocytes were observed to have inclusions in dogs inoculated both with Ethiopian and Mexican strains. Most neurons examined electronmicroscopically showed signs of infection, varying from a small granular or finely fibrillar viral matrix to numerous matrices accompanied by prolific numbers of virus particles occupying much of the perikaryon. These were found in all dogs inoculated with the Ethiopian strain but were rare with the Mexican isolate. Viral budding occurred from membranes of the rough endoplasmic reticulum, outer lamella of the nuclear envelope, and rarely from the plasma membrane.

Experimental chronic rabies in the cat.

Two cats, inoculated with a street rabies virus strain, survived with only some progressive debility and atrophy of musculature in the injected limb for 136 weeks. They had continuously increasing titers of neutralizing antibody in serum and in cerebrospinal fluid, and terminally they had high antibody titers in the brain. Virus was isolated from two brain specimens of one cat obtained at necropsy; isolation was successful only by explant culture and inoculation of explanted tissue into mice. Virus antigen was detected in eight sites in the brain and spinal cord of the same cat by frozen-section immunofluorescence. Lesions in the central nervous system consisted of neuronal degeneration and neuronophagia, associated with the prescence of inclusion bodies and widespread inflammatory cell inflitration into brain and spinal cord parenchyma, perineuronal sites, and perivascular spaces. The inflitrates contained lymphocytes, monocytes-macrophages, and a high proportion of plasma cells. These experimental cases of chronic progressive rabies resembled more closely subacute sclerosing panecephalitis of man than the usual subacute fatal rabies encephalitis of man and other mammalian species.

Studies on the poxvirus Cotia.

The poxvirus Cotia was studied by electron microscopy and by serological and biochemical analyses. Thin-sectioned preparations of infected Vero cells indicated that Cotia virus morphogenesis was similar to other mammalian poxviruses; unique filamentous structures and inclusion matrices were apparent in the cytoplasm. Complement fixation tests that included purified Cotia virions showed a reciprocal cross-reaction with rabbit myxoma virus and no cross-reaction with vaccinia virus. Serological results coupled with gradient polyacrylamide gel electropherograms of the structural proteins of purified Cotia, vaccinia, myxoma and fibroma viruses suggested that Cotia virus was similar to the latter two viruses. Agarose gel electropherograms of cleavage fragments of each of these virus DNAs digested with three separate restriction endonucleases showed that each of these viruses had a unique DNA gel profile.

Lyssavirus infection of muscle spindles and motor end plates in striated muscle of hamsters.

Immunofluorescent, light, and electron microscopy were used to document lyssavirus infection of muscle spindles and motor end plates. Virus particles were seen in the narrow intercellular space between sensory nerve endings and intrafusal muscle fibers; they were also observed budding from intracellular and plasma membranes of the latter. Involvement of motor nerves and motor end plates could only be demonstrated by electron microscopy. In nature, rabies virus invasion of the peripheral nervous system must involve centripetal spread across these junctions.

Antigenic relationship between human coronavirus strain OC 43 and hemagglutinating encephalomyelitis virus strain 67N of swine: antibody responses in human and animal sera.

Hemagglutinating encephalomyelitis virus of swine (HEV) was adapted to growth in suckling mouse brain. Electron micrographs of HEV-infected suckling mouse brain, prepared by negative staining and thin-section techniques, exhibited typical morphological characteristics shared with other members of the Coronaviridae. The adaptation of HEV to suckling mouse brain facilitated serologic testing by the use of common host reagents and compatible animal systems. With hemagglutination inhibition, complement-fixation, and neutralization tests, an antigenic relationship was demonstrated between human coronavirus OC 43 and HEV in specific immune and hyperimmune animal sera. Children and adults with seroconversion to OC 43 antigen had diagnostic rises in titer of antibody to HEV antigens. Individuals with seroconversion to human coronaviruse 229E and B814 demonstrated antibody to HEV but not diagnostic rises in titer. Swine with titers of antibody to HEV had lower or no detectable titers of antibody to coronavirus OC 43. Although the prevalence and geometric mean titer of antibody to OC 43 were higher than the titer of antibody to HEV in every group of normal humans tested, significant differences in antibody response to coronavirus OC 43 and HEV were seen between populations that did or did not have possible contact with swine. The evidence suggested that antibody to HEV in humans probably represented a heterologous response to infection with coronavirus OC 43. However, a heterotypic response to unknown or uncharacterized strains of coronavirus cannot be excluded.

Murine oncornavirus activation in the pancreas during infection with Venezuelan equine encephalitis virus.

Electron microscopic studies of the pancreases of 3-week-old ICR Swiss mice infected with Venezuelan equine encephalitis virus and killed 6 days post inoculation (at which time they were moribund) indicated significantly more type-C particles than were found in uninfected controls. This phenomenon was apparently possible because of the microanatomy of the pancreas, in which interstital spaces allowed accumulation of virus particles.