Electronmicroscopic identification of type C particles in cultured murine neuroblastoma.

Monolayer of murine neuroblastoma were treated with dexamethasone and examined by electronmicroscopy. Most of the treated cells were morphologically differentiated and exhibited type C virus particles which were budding from the cell surface. This in vitro system may be of great value for exploring the oncogenic potential of the virus, and its possible role in cell differentiation.     

Biological and biochemical characterization of a new isolate of baboon Papio papio endogenous type C virus]

A new strain of Baboon Papio papio endogeneous type C virus was isolated from the testis of an animal of this species. The strain was characterized biochemically and biologically. It presents a host-range different from that of the prototype strain of the same virus.     

Functional mechanisms of the cellular prion protein (PrPC) associated anti-HIV-1 properties

The cellular prion protein PrP(C)/CD230 is a GPI-anchor protein highly expressed in cells from the nervous and immune systems and well conserved among vertebrates. In the last decade, several studies suggested that PrP(C) displays antiviral properties by restricting the replication of different viruses, and in particular retroviruses such as murine leukemia virus (MuLV) and the human immunodeficiency virus type 1 (HIV-1). In this context, we previously showed that PrP(C) displays important similarities with the HIV-1 nucleocapsid protein and found that PrP(C) expression in a human cell line strongly reduced HIV-1 expression and virus production. Using different PrP(C) mutants, we report here that the anti-HIV-1 properties are mostly associated with the amino-terminal 24-KRPKP-28 basic domain. In agreement with its reported RNA chaperone activity, we found that PrP(C) binds to the viral genomic RNA of HIV-1 and negatively affects its translation. Using a combination of biochemical and cell imaging strategies, we found that PrP(C) colocalizes with the virus assembly machinery at the plasma membrane and at the virological synapse in infected T cells. Depletion of PrP(C) in infected T cells and microglial cells favors HIV-1 replication, confirming its negative impact on the HIV-1 life cycle.     

Effect of human interferon on viral production in a cell line chronically infected by a type D retrovirus (Mason-Pfizer virus)]

Human interferon specifically inhibits the viral multiplication in a human cell line infected by a type D retrovirus, the Mason-Pfizer virus (MPV). This inhibition is less important than for type C viruses.     

A thermosensitive inhibitor of the replication of polyomavirus, an extract from BHK2I cells transformed by the Tsa mutant of this virus

BHK21 cells transformed by wild type or Ts3 mutant polyoma virus contain an inhibitor of polyoma virus replication when grown at permissive (36 degrees C) as well as non-permissive temperature (39 +/- 0.5 degrees C). Cells transformed by the Tsa mutant contain the inhibitor at the permissive but not at the non-permissive temperature. The inhibitor reappears in the latter cells however, upon shift from the non-permissive to the permissive temperature. If a reversible protein inhibitor (methionyl-adenylate, reversible inhibitor of the aminoacyl-t-RNA synthetase) is applied during the temperature shift experiments, the inhibitor does not reappear indicating that new protein synthesis is required for the recovery of its activity.     

Electronmicroscopic identification of type C particles in cultured murine neuroblastoma

Summary Monolayer of murine neuroblastoma were treated with dexamethasone and examined by electronmicroscopy. Most of the treated cells were morphologically differentiated and exhibited type C virus particles which were budding from the cell surface. This in vitro system may be of great value for exploring the oncogenic potential of the virus, and its possible role in cell differentiation.Acknowledgments. The authors wish to thank Dr K.N. Prasad, Department of Radiology, University of Colorado Medical Center, for providing the NBP₂ clone, and Mr P. Reimann for photographic assistance. This research was supported in part by NIH Grant NS 11650 to T.H.W.     

The replication of a xenotropic murine C type virus in some mammalian cells. Definition of a specific antigen]

The use of our mink cell line maintained in vitro infected with the murine xenotropic AT 124 virus, and that of a (W/Fu x bn) f1 rat anti-124 serum allow us to define a new cell surface antigen specific of murine xenotropic type C viruses.     

Expression of an antigen associated with Gross virus on the surfaces of murine cells producing an oncornavirus from the radioleukemia of C57BL/6 mice]

A leukemogenic viral complex was demonstrated in cultures of 13-3 C cell line derived from a C57BL/6, radiation leukemia virus (RadLV-Rs) induced tumor. Both 13-3C and leukemic cells induced in C57BL/6 mice by 13-3C virus carry a cell surface antigen associated with Gross leukemia virus (GCSAa). These findings point to a close similarity between these antigens and those of murine endogenous ecotropic viruses.     

Emerging topics and new perspectives on HLA-G

Following the Fifth International Conference on non-classical HLA-G antigens (HLA-G), held in Paris in July 2009, we selected some topics which focus on emerging aspects in the setting of HLA-G functions. In particular, HLA-G molecules could play a role in: (1) various inflammatory disorders, such as multiple sclerosis, intracerebral hemorrhage, gastrointestinal, skin and rheumatic diseases, and asthma, where they may act as immunoregulatory factors; (2) the mechanisms to escape immune surveillance utilized by several viruses, such as human cytomegalovirus, herpes simplex virus type 1, rabies virus, hepatitis C virus, influenza virus type A and human immunodeficiency virus 1 (HIV-1); and (3) cytokine/chemokine network and stem cell transplantation, since they seem to modulate cell migration by the downregulation of chemokine receptor expression and mesenchymal stem cell activity blocking of effector cell functions and the generation of regulatory T cells. However, the immunomodulatory circuits mediated by HLA-G proteins still remain to be clarified.     

The biology of schizophrenia

Conclusions Genes may be relevant not only to predisposition but also to the type of schizophrenic illness which occur, and determine whether symptoms of the type I or type II syndromes or a combination of the two are the major manifestations. Both syndromes, howerver, might be caused by a single agent, e.g.a. virus. Thus, amongst the population of patients at risk there is a group who experience a primary neurochemical disturbance (e.g. of dopaminergic transmission). This becomes manifest in positive symptoms (delusions, hallucinations and thought disorder) and might result from an affinity of the virus for a particular neurochemical structure (e.g. the D₂ dopamine receptor or a molecule concerned in its regulation). Within this population however, is a sub-group that is predisposed to a more malignant and widespread disease. In these patients the virus gains further footholds in the nervous system, with the consequence that the disease acquires the characteristics of a chronic encephalitis. It is in these cases that there is evidence of structural change (although the site of the presumed cell loss has yet to be determined) and when present this change is associated with intellectual impairment and negative symptoms (the type II syndrome).Thus the disturbance underlying the type I syndrome is a neurochemical one which accounts for the reversibility of some schizophrenic symptoms and illnesses, and their response to neuroleptic drugs. It is compatible with Bleuler's view of schizophrenia as a functional psychosis which can be clearly distinguished from dementia. The change underlying the type II syndrome is progressive and irreversible and accounts for poor long-term outcome. To this form of illness Kraepelin's term dementia praecox can be applied with the term dementia retaining its contemporary connotation of organic psychosis.The 1981 Curran Lecture delivered at St. George's Hospital Medical School.     

Inclusion of Gross virus cell surface associated antigen in liposomes]

The Gross virus associated cell surface antigen GCSAa was extracted from (C58NT)D cells by solubilization of membranes with detergent and partially purified. This antigen was entraped in liposomes. Absorption experiments of the cytotoxic activity towards EmaleG2 cells of a W/Fu anti (C58NT)D serum showed the presence of the antigen at the surface of sensibilized liposomes.     

Chromsome aberrations in cattle raised on bracken fern pasture

Summary Thirteen cows maintained on natural bracken fern (Pteridium aquilinum) were analyzed cytogenetically. The frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. We discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals.Acknowledgments. We are grateful to Dr F. J. Benesi, Dr J. L. Guerra and Dr I. L. Sinhorini for performing some of the clinical and pathological analyses; O. P. Ferraz, L. A. Tadeu Dias, L. F. Feitosa and A. M. N. Paiva for technical assistance; and to Dr N. H. C. Castro and Dr C. de Araujo Peres for critical and statistics review, respectively. Research was supported by CNPq FAPESP and CAPES.     

Reversion of virus N-1 resistant mutant of blue-green algaNostoc muscorum

Summary The reversion of N-1 virus resistant strain of the algaNostoc muscorum was studied by inoculating parent virus in the resistant culture at various incubations. A fraction of virus resistant cells reverted to wild sensitive type with the reversion rate of 3.99×10^–6/cell/generation.We gratefully acknowledge Dr H.K. Pande and Dr S. Patnaik, Crops and Soils Division.     

Changes in the glomerular endothelia connected with gross virus infection of mice

Riassunto Gli autori hanno studiato al microscopio elettronico cellule dell'endotelio glomerulare di topo infettato con virus della leucemia murina (Gross virus) e hanno dimostrata la esistenza di particelle virali all'interno di esse.

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This work was supported in part by a grant from C.N.R. Italy.     

Isolation of a pathogenic rhabdovirus of brown trout (Salmo trutta L., 1766)]

A Rhabdovirus pathogenic both for Rainbow and Brown Trout has been isolated from Brown Trout suffering heavy mortalities associated with muscular haemorrages and necrotic lesions of kidney and spleen. According to seroneutralization tests and host range, this virus appears to be different from the other known salmonids rhabdoviruses. Upon the basis of its in vitro gross characteristics, it is identical to Viral Haemorragic Septicemia Virus (VHS), F1 serotype, but differs from Infectious Hematopo?etic Necrosis and VHS type II viruses.     

A rapid method of following the spontaneous regression of experimental leukemias

Summary Transplantation of virus and chemically induced leukemias from C3H/He-mgxAKR/F₁ hybrid mice into C3H/He-mg males induced leukemias in the latter, which was followed by a spontaneous regression of the disease within a few days. The regression of leukemia could easily be followed by measuring the changes in the pyruvate kinase activity of para-aortic lymph node cells.     

Influence of hydrocortisone on cytopathic effect of Newcastle disease virus and stability to freezing of vescicular stomatitis virus.

The presence of hydrocortisone in virus-infected cell cultures leads to enhancement of the syncytia forming ability of Newcastle disease virus and to production of vescicular stomatitis virus particles which loose their infectivity upon storage below 0 degrees C.     

Immunological sensitization following inapparent infection with dengue virus type 3 in rhesus monkeys.

Rhesus monkeys previously given dengue virus type 3, without apparent viremia or antibody response, exhibited a secondary-type response upon reinoculation. These data suggest that monkeys can be immunologically sensitized to dengue virus without detectable antibody production.     

Antiviral activity of coralloid root ofCycas revoluta extract against some viruses of tomato plant

Summary Crude coralloid root extract ofCycas revoluta showed significant antiviral activity against viruses of the tomato plant (PVX, PVY, TMV, TAV and TRSV) when applied 24 h before virus inoculation, or when mixed with different virus inocula before virus inocultion, in hypersensitive and systemic hosts. No such inhibition was observed when extract was applied 24 h after virus inoculation. TAV did not show any inhibitory response in a systemic host.Authors are thankful to Dr S. N. Gupta and Dr (Smt.) K. Shukla for their valuable guidance and providing laboratory facilities and U.G.C. for financial assistance.     

Intracisternal A type particles of the extraocular muscle of hereditary muscular dystrophy mouse.

Intracisternal A type virus (IA) particles were observed in the extraocular muscle fiber of hereditary muscular dystroph mouse. The particles appeared approximately 65-75 mmu in diameter, with electron lucent cores.