An antiviral factor fromMelia azedarach L. prevents Tacaribe virus encephalitis in mice

Summary Treatment of neonatal mice with an antiviral factor, (AVF), obtained from the leaves ofMelia azederach L. protected them against lethal encephalitis caused by Tacaribe virus inoculation. The degree of protection obtained varied from 66% to 100% depending on the virus dose. Similarly, administration of AVF to nursing mothers protected their offspring from developing virus encephalitis. AVF does not directly inactivate Tacaribe virus; it inhibits an early step (s) in the replication process in cell cultures.Dedicated to Prof. Luis Leloir on his 80th birthday.Acknowledgment. This study was supported by Grant 9353/84 from the Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET), Argentina.     

Infection with viruses of the Tacaribe group in thymectomized mice

Resumen La timectomia en ratones recien nacidos los protege contra dosis mortales de virus Junin, Machupo, Tacaribe y Pichinde, pero no contra una dosis similar de virus Amapari. Todos estos virus pertenecen al grupo Tacaribe. Se discute el origin del fenomeno y la importancia del mismo.     

Non-viraemic transmission of tick-borne encephalitis virus: a mechanism for arbovirus survival in nature

The vectors of arthropod-borne viruses (arboviruses) become infected by feeding on the viraemic blood of an infected animal. This theory is based on transmission studies involving artificial infection of vertebrate hosts by syringe inoculation. To reproduce natural conditions of virus transmission, infected and uninfected vectors (ticks) of tick-borne encephalitis virus, the most important arbovirus in Europe, were allowed to feed together on uninfected wild vertebrate hosts. The greatest numbers of infected ticks were obtained from susceptible host species that had undetectable or very low levels of viraemia. The results suggest that nonviremic transmission is an important mechanism for the survival of certain arboviruses in nature.     

The influence of cold or isolation stress on resistance of mice to West Nile virus encephalitis

The effect of cold or isolation stress on mortality rate and brain virus level were investigated in mice infected with West Nile virus (WNV). Exposure of mice for 5 min/day to cold water (1 +/- 0.5 degrees C) for 8-10 days resulted in 92% mortality as compared to 47% in control mice (p less than 0.001). Mice housed in individual cages (isolation stress) were also more susceptible to WN viral infection, as shown by increased mortality rate reaching 85% as compared to 50% in mice housed 6 per cage (p less than 0.01). Cold or isolation stress increased blood brain and spleen virus levels as early as 2 days after inoculation. After 8 days of isolation or cold stress, mice inoculated with WNV had 8.9 and 9.0 log10 plaque forming units in the brain, respectively, as compared to 6.9 in the control (p less than 0.01-0.001). Furthermore, lymphoid organs such as spleen and thymus showed severe mass loss. These data suggest that physical or non-physical stress situations enhance WNV encephalitis by accelerating virus proliferation and increase mortality in mice.     

The influence of cold or isolation stress on resistance of mice to West Nile virus encephalitis

Summary The effect of cold or isolation stress on mortality rate and brain virus level were investigated in mice infected with West Nile virus (WNV). Exposure of mice for 5 min/day to cold water (1±0.5°C) for 8–10 days resulted in 92% mortality as compared to 47% in control mice (p<0.001). Mice housed in individual cages (isolation stress) were also more susceptible to WN viral infection, as shown by increased mortality rate reaching 85% as compared to 50% in mice housed 6 per cage (p<0.01). Cold or isolation stress increased blood brain and spleen virus levels as early as 2 days after inoculation. After 8 days of isolation or cold stress, mice inoculated with WNV had 8.9 and 9.0 log₁₀ plaque forming units in the brain, respectively, as compared to 6.9 in the control (p<0.01–0.001). Furthermore, lymphoid organs such as spleen and thymus showed severe mass loss. These data suggest that physical or non-physical stress situations enhance WNV encephalitis by accelerating virus proliferation and increase mortality in mice.     

Immunologic blood-brain barrier in the polyoma virus--Syrian hamster system]

The authors report premilinary results of an experiment on permeability of the blood-brain barrier (BBB) to anti-tumor virus-induced immunological factors in the polyoma virus/Syrian Hamster system. The animals were protected by subcutaneous or intracranial injections with virus before challenge with polyoma virus transformed cells by both routes. BBB seemed to be permeable to the efferent part of the subcutaneously induced immune reaction. On the contrary, antigenic information introduced in the central nervous system was trapped inside the BBB. Thus the BBB might offer a "one-way" permeability in this system.     

Effectiveness of intranasal immunization with Myxovirus influenzae neuraminidase in mice]

An intranasal immunization with a A/PR8/34-isolated NA, protected mice as well as the whole virus and A/Hong Kong/1/68 virus against a subsequent infection with mice-adaptated A/PR8/34 strain.     

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.     

Diminution de radiosensibilité du rat adulte en hypothermie profonde

Summary Using an appropriate technique, we put adults rats of both sexes under deep hypothermy (rectal temperature of 14–15°C). Under these conditions, the respiration and the cardiac rhythm are definitely slowed down.(1) Rats irradiated in a state of deep hypothermy with lethal doses of 800 and 900 r of X-rays, are partially protected. 50% of these animals survived more than 30 days, whereas all control animals died after 17 days.(2) The same degree of protection is obtained if the cooling is made in the presence of oxygen or under an air pressure of 1.25 atmosphere.     

Isolation of a Soldado-like virus (Hughes group) fromOrnithodorus maritimus ticks in Ireland

Summary Three isolations of a virus of the Hughes group were obtained from seabird ectoparasites,Ornithodoros (Alectorobius) maritimus, on Great Saltee Island, Ireland. The agent is closely related to Soldado virus, originally obtained from related ticks near Trinidad, West Indies, and represents the second recorded tickborne arbovirus in Ireland.These investigations were supported in part by the Royal Irish Academy (Praeger Fund).     

Protective effect of Shigyaku-to,a traditional Chinese herbal medicine,on the infection of herpes simplex virus type 1 (HSV-1) in mice

The antiviral activity of Shigyaku-to (TJS-109), a traditional Chinese herbal medicine, was investigated in mice infected with herpes simplex virus type 1 (HSV-1). TJS-109 is a combination of the medicinal plant extracts fromZingiberis siccatum rhizoma,Aconiti tuber andGlycyrrhizae radix in a specific proportion. Mice infected with a 10 LD₅₀ dose of HSV-1 were treated with TJS-109 orally at doses of 1.25 to 20 mg/kg 2 days before, and 1 and 4 days after the infection. The treated groups had 80% (1.25 mg/kg), 40% (5 mg/kg) and 23% (20 mg/kg) mortality rates 25 days after the infection as compared with a 100% mortality rate in control mice treated with saline. When HSV-1 infected mice (recipients) received CD8⁺T cell fractions derived from spleens of mice treated with TJS-109 (donors), 70% of recipients survived, as compared with 0% survivors in the groups of mice treated with saline, B cell fractions, CD4⁺ T cell fractions or macrophage-enriched fractions prepared from the same donors. TJS-109 did not show any virucidal activities against HSV-1 or any virostatic activities on the growth of HSV-1 in Vero cells. These results suggest that TJS-109 protected mice exposed to lethal amounts of HSV-1 through the activation of CD8⁺ T cells.     

The influence of MuLV and SV40 viruses on senescence in mouse fibroblasts in vitro

Summary Mouse cells productively infected with Moloney leukaemia virus (MuLV) underwent senescence in a manner similar to control cells, although they recovered more readily as an established line. Rapidly growing cell lines were also obtained following simian virus 40 (SV40) infection of senescent cells. However, superinfection of senescent MuLV-producing cells by SV40 led to slower growing cells with a reduced output of infectious MuLV.     

The influence of MuLV and SV40 viruses on senescence in mouse fibroblasts in vitro.

Mouse cells productively infected with Moloney leukaemia virus (MuLV) underwent senescence in a manner similar to control cells, although they recovered more readily as an established line. Rapidly growing cell lines were also obtained following simian virus 40 (SV40) infection of senescent cells. However, superinfection of senescent MuLV-producing cells by SV40 led to slower growing cells with a reduced output of infectious MuLV.     

C-type virus particles in lymphocytes cultured from cows with persistant lymphocytosis. Preliminary results on French cattle stock]

C type virus particles were shown in cultures of lymphocytes originating from cows with persistent lymphocytosis. These observations on French cattle are in complete accordance with data previously obtained in the USA. Viral replication is highly stimulated by the addition of phytohemagglutinin in the culture medium. Several morphological and biological properties, specific to the bovine virus differentiate this virus from C type viruses of other species.     

Isolation of a Soldado-like virus (Hughes group) from Ornithodorus maritimus ticks in Ireland.

Three isolations of a virus of the Hughes group were obtained from seabird ectoparasites, Ornithodoros (Alectorobius) maritimus, on Great Saltee Island, Ireland. The agent is closely related to Soldado virsu, originally obtained from related ticks near Trinidad, West Indies, and represents the second recorded tickborne arbovirus in Ireland.     

A cell line particularly susceptible to bovine enteric Coronavirus replication: HRT 18 cells

Bovine enteric Corona virus (BEC) multiplies spontaneously with very high efficiency in HRT 18 cells; this line established from human rectum adenocarcinoma presents some properties of the differentiated brush border cell of the intestinal villi. Titers obtained are very high (5 x 10(7) TCID 50/ml virus strain F15). The virus produced had the characteristic of BEC: shape, spikes, density 1.19, hemadsorption and hemagglutination of rat erythrocytes. Human and dog enteritic corona viruses replicate also in HRT 18 cells.     

Isolation of the yellow fever virus from an egg-cluster and the larvae of the tick Amblyomma variegatum]

The yellow fever virus is isolated in natura from eggs of a Tick Amblyomma variegatum. It is then isolated from larvae issued from the same egg-cluster and also from blood of a monkey bitten by larvae of the same origin. It is reported that the same virus has been previously obtained from adults of the same species of Tick. An acarine appears for the first time as a sylvatic vector and reservoir (at least temporary) of yellow fever.     

Detection of human cytomegalovirus (HCMV) DNA from cell-free plasma of immunosuppressed patients by nested PCR: influence of nucleic acid extraction method

Conclusions Blood cells and plasma preparations from HCMV-seropositive healthy blood donors were all nPCR negative. Detection of HCMV DNA from PBMC and granulocytes (DNAemia) of immunosuppressed patients by nPCR did not correlate with the isolation of infectious virus from these cell populations in cell culture (viremia). However HCMV could be isolated in 60% of cases from other materials of the same patient. HCMV DNA detected in blood cells persisted for up to one year in an asymptomatically infected individual after NTX. The sensitivity of HCMV DNA detection in cell-free plasma (up to 5 fg) depended on the method used for DNA isolation. The rate of HCMV DNA detection in plasma was lower than in leukocytes. In all cases of positive plasma PCR infectious virus could be isolated from any other material of the symptomatically infected patients. Therefore HCMV DNA PCR from plasma of immunosuppressed patients seems to be a suitable and easy alternative to HCMV RT/PCR for routine diagnosis of HCMV disease.     

Isolation in east Senegal of a yellow fever virus strain from a pool of Aedes belonging to the subgenus Diceromyia]

During an epidemiological survey of yellow fever in Eastern Senegal, one strain of yellow fever virus was isolated in December 1976 from wild Mosquitoes. This first isolate obtained in nature from Aedes subgenus Diceromyia shows the primordial part these vectors may have in the area studied. It corroborates the existence of a selvatic focus of yellow fever in this region. It also gives information on the transmission cycle in a dry area.