Detection of caprine arthritis-encephalitis- and maedi-visna viruses using the polymerase chain reaction

Summary The polymerase chain reaction (PCR) was used to demonstrate proviral DNA of lentiviruses of small ruminants in cultured cells. Primers for the Taq polymerase were selected in the GAG gene of Icelandic maedi-visna virus and POL gene of caprine arthritis-encephalitis (CAE) virus. Using PCR, proviral DNA of CAE virus was detected at 1 day post infection, 4 days beforeviral protein could be demonstrated using a sensitive immunoblotting protocol and 6 days before the appearance of syncytia. Primers derived from the published sequence of CAE virus successfully primed for the synthesis of homologous virus and Icelandic maedi-visna viruss but not for maedi-visna virus isolated in The Netherlands. In contrast, primers derived from the GAG region of Icelandic maedi-visna virus allowed the amplification of DNA of homologous virus, maedi-visna virus isolated in The Netherlands as well as CAE virus.     

Mechanisms of heterotypic immunity against canine distemper.

Hep-2 cells infected with measles virus (MV) for as short as 6 h became refractory to superinfection with canine distemper virus (CDV) but not to vesicular stomatitis virus (VSV). The exact mechanism of such interference is unknown but probably occurs after virus attachment and penetration. These results verify the suggestion that virus interference may be a mechanism of heterotypic protection against canine distemper.     

Induction, by 5-bromo-2'-deoxyuridine, of a "foamy" virus previously undetected in hamster cells transformed by SV40]

TSV5 clone 2 cells in normal conditions of culture contain only an expressed RNA virus (R-type virus). However, exposure of the cells to 5-bromo-2'-deoxyuridine with dexamethasone, induced synthesis of a syncitium-forming ("Foamy") virus. In other hamster cell lines, the same treatment fails to induce a "foamy" virus. The origin of this "foamy" virus is discussed.     

Evidence for mimicry by viral antigens in animal models of autoimmune disease including myocarditis

Molecular mimicry of viral antigens with self determinants has been proposed as one of the pathogenic mechanisms in autoimmune disease. Evidence of viral mimicry in animal models of autoimmunity is accumulating. Murine adenovirus, Semliki forest virus, lactate dehydrogenase-elevating virus, herpes simplex virus type-1, hepatitis B virus, encephalomyocarditis virus, Theiler's murine encephalomyelitis virus, Coxsackievirus and cytomegalovirus have been found to mimic physiologically important host proteins. However, epitope homology of a viral and self determinant is not in itself strong evidence for mimicry as a pathogenic mechanism. The mimicking determinant must also be capable of inducing disease in the absence of replicative virus. Animal models provide evaluation of the viral trigger, and development and therapy for autoimmune diseases. Identification of host proteins that can induce disease together with the knowledge of immune system dysregulation, genetic association and environmental factors may lead to improved immunotherapeutic strategies for human autoimmune diseases.     

Viral adenosine triphosphatase.

The catalytic and immunological properties of an adenosine triphosphatase from different types of virus have been studied. The avian myeloblastosis virus has been found to be specialized in holding this enzyme in a highly active state as compared to other virus with respect to their host cell enzyme. Catalytically myeloblastosis virus and Rous virus ATPase behave alike, while that of the Reo virus is significantly different.     

The implications of viral reservoirs on the elite control of HIV-1 infection

The mechanisms by which a small percentage of HIV-1 infected individuals known as elite suppressors or controllers are able to control viral replication are not fully understood. Early cases of viremic control were attributed to infection with defective virus, but subsequent work has demonstrated that infection with a defective virus is not the exclusive cause of control. Replication-competent virus has been isolated from patients who control viral replication, and studies have demonstrated that evolution occurs in plasma virus but not in virus isolates from the latent reservoir. Additionally, transmission pair studies have demonstrated that patients infected with similar viruses can have dramatically different outcomes of infection. An increased understanding of the viral factors associated with control is important to understand the interplay between viral replication and host control, and has implications for the design of an effective therapeutic vaccine that can lead to a functional cure of HIV-1 infection.     

Modification of the skin feeding site by tick saliva mediates virus transmission.

A tick vector of Thogoto (THO) virus was shown to secrete a factor in saliva which potentiates the transmission of THO virus to uninfected ticks feeding on an apparently non-viraemic host. The effect of the saliva activated transmission (SAT) factor on the virus occurred at the site of inoculation in the skin and was apparent even when the virus was introduced 3 days after the SAT factor. The results suggest that tick saliva can play an important role in disease transmission by virtue of host modification at the site of feeding.     

基于度相关性的病毒传播模型及其分析

近年来网络病毒传播已对网络安全构成严重威胁.研究表明,互联网宏观拓扑结构与病毒传播有很大关系.度相关性是互联网宏观拓扑的一个重要特征,度相关性的改变意味着互联网拓扑结构的变化.通过度相关特征分析,发现互联网的异配性呈现减弱趋势;本文使用DPR算法构造连续匹配系数的网络拓扑,以便在具有不同匹配系数上的网络上进行病毒传播实验,以此研究病毒的传播速度、稳态感染率、传播临界值;然后根据传统病毒传播模型SIS,建立了适合因特网上的病毒传播模型SIS-DVDI,并进行病毒传播实验,分析了病毒传播的稳态特性和瞬态特性;最后根据先前仿真实验得出的结论探讨了网络病毒的防护措施.     

Modification of the skin feeding site by tick saliva mediates virus transmission

A tick vector of Thogoto (THO) virus was shown to secrete a factor in saliva which potentiates the transmission of THO virus to uninfected ticks feeding on an apparently non-viraemic host. The effect of the saliva activated transmission (SAT) factor on the virus occurred at the site of inoculation in the skin and was apparent even when the virus was introduced 3 days after the SAT factor. The results suggest that tick saliva can play an important role in disease transmission by virtue of host modification at the site of feeding.     

Viral adenosine triphosphatase

Summary The catalytic and immunological properties of an adenosine triphosphatase from different types of virus have been studied. The avian myeloblastosis virus has been found to be specialized in holding this enzyme in a highly active state as compared to other virus with respect to their host cell enzyme. Catalytically myeloblastosis virus and Rous virus ATPase behave alike, while that of the Reo virus is significantly different.Acknowledgment. The author would like to thank Dr. E. Racker for his continuous encouragement and helpful discussion during this piece of work.     

Diptera of Calliphora genus, potential carriers and spreaders of swine vesicular disease virus]

Swine Vesicular Disease virus ingested by the adult fly Calliphora persists several days in the digestive tract of the insect and is eliminated in feces. The virus ingested by the insect at larval stage has been recovered from the digestive tract and feces of adult flies. Thus, the dissemination of the virus, even in a limited fashion, seems to be possible and attention is chiefly centered on the second process.     

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.     

In vitro proliferation of human large granular lymphocytes with v-raf/v-myc recombinant retrovirus

The effect of infection with a retrovirus carrying v-raf/v-myc oncogenes (J2 virus) on the in vitro proliferation of human large granular lymphocytes (LGL) was investigated. LGL infected with J2 virus (J2LGL), unlike uninfected cells, grew with a proliferation peak eight days after infection. Such cells retained the morphology and functional properties typical of LGL. Furthermore, 5% of J2LGL produced virus the day after infection, whereas non-virus production was detectable five days later. These data indicate that J2 virus provides a transient mitogenic signal for LGL.     

Protective and immunostimulating activity of a low dose of cyclophosphamide in the experimental infection of mice with foot-and-mouth disease virus

Administration to mice of a low, non-immunosuppressive dose of cyclophosphamide 4 days before infection with foot-and-mouth disease virus decreases viral replication, enhances the immune response against the virus and prevents pancreatic damage.     

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.     

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.     

Protective and immunostimulating activity of a low dose of cyclophosphamide in the experimental infection of mice with foot-and-mouth disease virus

Summary Administration to mice of a low, non-immunosuppressive dose of cyclophosphamide 4 days before infection with foot-and-mouth disease virus decreases viral replication, enhances the immune response against the virus and prevents panceatic damage.     

Discovery and purification of a virus in gland hyperplasia of insects. Study of Merodon equistris F. (Diptera, Syrphidae)]

ADNA virus was purified from the salivary gland affected by a large proliferation in the Diptera Merodon equestris. Structure, nucleic acid as well as development and intracellular cycle of the virus have been characterized.