Herpes simplex virus in mice: electron microscopy of neural spread

Herpes simplex virus rapidly infected the trigeminal nerves of mice after intranasal inoculation. Centripetal neural spread was suggested by histologic evidence of encephalitis in the area of attachment of the trigeminal nerve. Furthermore, electron microscopy revealed virus replication primarily within Schwann cells of the trigeminal nerve, and neurons of the gasserian ganglion.     

Tumors induced in hamsters by simian virus 40: persistent subviral infection

The cells of two hamster ependymomas, originally induced by intracerebral inoculation with simian virus 40 in newborn animals, have been serially cultured in vitro. None of the virus was detected in cell-free culture fluids or cell lysates. All cells retained their neoplastic potential when newborn hamsters were inoculated. Data suggest that viral nucleic acid is permanently present in some tumor cells.     

Simulation modelling of potato virus Y spread in relation to initial inoculum and vector activity

Potato virus Y(PVY) is a non-persistent virus that is transmitted by many aphid species and causes significant damage to potato production. We constructed a spatially-explicit model simulating PVY spread in a potato field and used it to investigate possible effects of transmission efficiency, initial inoculum levels, vector behavior, vector abundance, and timing of peak vector activity on PVY incidence at the end of a simulated growing season. Lower PVY incidence in planted seed resulted in lower virus infection at the end of the season. However, when populations of efficient PVY vectors were high, significant PVY spread occurred even when initial virus inoculum was low. Non-colonizing aphids were more important for PVY spread compared to colonizing aphids, particularly at high densities. An early-season peak in the numbers of noncolonizing aphids resulted in the highest number of infected plants in the end of the season, while mid-and late-season peaks caused relatively little virus spread. Our results highlight the importance of integrating different techniques to prevent the number of PVY-infected plants from exceeding economically acceptable levels instead of trying to control aphids within potato fields. Such management plans should be implemented very early in a growing season.     

Neoplastic transformation of hamster astrocytes in vitro by simian virus 40 and polyoma virus

Astrocytes in cultures of brain cells from fetal or newborn hamsters undergo neoplastic transformation after infection with simian virus 40 or polyoma virus. Subcutaneous or intracerebral inoculation of the transformed brain cells into newborn or adult hamsters produces progressively enlarging astrocytomas at the sites of injection. Astrocytomas produced by polyomatransformed cell lines are histologically better differentiated, but grow more rapidly and metastasize more frequently, than astrocytomas produced by cell lines transformed by simian virus 40. These observations make available in vitro models of virus-induced oncogenesis in astrocytes and provide simple techniques for obtaining astrocytoma cell lines suitable for screening studies of chemical agents effective against astrocytomas.     

Mammary tumor virus antigen: sensitive immunoassay

A rapid, sensitive immuno-assay for mammary tumor virus antigen based on inhibition of passive hemagglutination has been developed. The method permits measurement of this antigen in mouse milk from which the fat has been removed.     

烤烟普通花叶病毒病田间自然传播能力研究

通过田间试验,研究了8类不同有效成分农药对烟草病毒病的防治效果.结果表明:8类参试药剂中除18%抑毒星和0.5%抗毒丰在烤烟生长前期对病毒病的预防有微弱效果外,其他参试药剂对烟草病毒病均未表现出预防效果,烤烟在有病原存在的情况下,施药预防与不施药预防几乎没有区别.     

Swine influenza-like viruses in turkeys: potential source of virus for humans?

Influenza A viruses (subtype H1N1), recently isolated from turkeys in different areas of the United States, were determined to be closely related to strains typically associated with pigs. This conclusion was based on comparisons of H1N1 isolates from pigs, humans, ducks, and turkeys with polyclonal and monoclonal antibodies, RNA-RNA competitive hybridization, and replication studies. One of the H1N1 isolates from turkeys caused influenza in a laboratory technician, who displayed fever, respiratory illness, virus shedding, and seroconversion. These results suggest that turkeys as well as pigs are involved in the maintenance of these viruses and their transmission to humans.     

Simian tumor virus isolate: demonstration of cytopathic effects in vitro

Several cell lines that were derived from primates and inoculated with virus originally obtained from a spontaneous mammary carcinoma showed cytopathic effects characterized by multinucleation. These cytopathic effects appeared as early as 24 holurs after inoculation. Multinucleated cells contained virus particles characteristic of the original virus isolate.     

Neoplastic transformation in vitro of hamster lens epithelium by simian virus 40

Hamster lens epithelium infected with simian virus 40 underwent transformation in vitro and produced tumors when injected into homologous hosts. Undisturbed lens epithelium in man and experimental animals has not been observed to undergo neoplastic change. The virus-induced tumors contained undifferentiated cells that were either polygonal or spindle-shaped. Their origin from lens epithelium seems certain since it is possible to isolate this unique structure free of connective tissue and blood vessels.     

Predisposition to hookworm infection in humans

Frequency distributions of parasitic helminths within human communities are invariably highly aggregated, the majority of worms occurring in relatively small fractions of the host populations. It has been suggested that the heavily infected individuals are predisposed to this state, not by chance, but by as yet undefined genetic, ecological, behavioral, or social factors. Analyses of individual post-treatment patterns of hookworm reinfection among 112 villagers in an endemic area of West Bengal provide quantitative evidence of predisposition to heavy infection. This observation has implications for the design of control programs based on chemotherapy because of the potential economic advantage of selective or targeted treatment as opposed to mass or blanket treatment.     

CD40 agonists alter tumor stroma and show efficacy against pancreatic carcinoma in mice and humans

Immunosuppressive tumor microenvironments can restrain antitumor immunity, particularly in pancreatic ductal adenocarcinoma (PDA). Because CD40 activation can reverse immune suppression and drive antitumor T cell responses, we tested the combination of an agonist CD40 antibody with gemcitabine chemotherapy in a small cohort of patients with surgically incurable PDA and observed tumor regressions in some patients. We reproduced this treatment effect in a genetically engineered mouse model of PDA and found unexpectedly that tumor regression required macrophages but not T cells or gemcitabine. CD40-activated macrophages rapidly infiltrated tumors, became tumoricidal, and facilitated the depletion of tumor stroma. Thus, cancer immune surveillance does not necessarily depend on therapy-induced T cells; rather, our findings demonstrate a CD40-dependent mechanism for targeting tumor stroma in the treatment of cancer.     

Leukemia, lymphoma, and osteosarcoma induced in the Syrian golden hamster by simian virus 40

Leukemia, lymphoma, and osteogenic and anaplastic sarcomas develop in Syrian golden hamsters inoculated intravenously at 3 weeks of age with simian virus 40, which is a popova virus. Previously, only RNA and herpes DNA viruses have been recognized as capable of inducing leukemia and lymphoma in mammals. The significance of these findings is emphasized in relation to the nature of viral agents that may be involved in analogous diseases of man.     

Complement-fixing antigens in hamster tumors induced by the Bryan strain of Rous sarcoma virus

Hamster tumors transplanted subcutaneously from primary intracranial tumors which developed after inoculation of the Bryan strain of Rous sarcoma virus, contained virusspecific tumor antigens indistinguishable from those induced by the Schmidt-Ruppin strain.     

Evaluation of plant virus infection of cereal crops and prediction of spread of disease in Primorskii krai

The spread of ten viruses has been revealed on cereal crops in Primorskii krai: brome mosaic, barley stripe mosaic, wheat streak mosaic, northern cereal mosaic, barley yellow dwarf, maize dwarf mosaic, oat Russian mosaic, rice streak, maize dwarf mosaic, and Poa semi-latent. The level of infection of row crops didn’t exceed 1% and 2.2% in collection and competitive variety testing nurseries. Barley stripe mosaic virus (barley), brome mosaic virus (wheat), and northern cereal mosaic virus (oat) spread the most.