Virus

About: Virus is a research topic. Over the lifetime, 136914 publications have been published within this topic receiving 5209107 citations. The topic is also known as: infectious agent & viruses.

A recombinant plasmid from which an infectious adeno-associated virus genome can be excised in vitro and its use to study viral replication.

Abstract: A recombinant plasmid carrying an infectious adeno-associated viral genome was constructed that differs in several key respects from previously described recombinants First, the vector is pEMBL8(+), which allows isolation of viral plus and minus strands Second, the inserted viral sequences contain two XbaI cleavage sites that flank the viral coding domain These inserts do not affect replication of the virus, and they allow nonviral sequences to be easily inserted between the cis-acting terminal repeats of adeno-associated virus Third, the viral genome is flanked by PvuII cleavage sites that allow the entire, infectious viral chromosome to be excised from plasmid sequences in vitro Viral DNA was replicated more efficiently within adenovirus-infected 293 cells if it was excised from the vector with PvuII before transfection Presumably, the increased efficiency reflects bypass of the excision step which must normally precede replication when a recombinant plasmid enters the nucleus The ability to bypass the excision step was exploited to search for a viral function required specifically for excision of the viral genome from the integrated state None of the mutants tested identified a gene product required for excision that was not also essential for replication The ability to produce pure populations of viral plus and minus strands was used to demonstrate that both strands are infectious Images

Reservoirs for HIV-1: Mechanisms for Viral Persistence in the Presence of Antiviral Immune Responses and Antiretroviral Therapy

Abstract: The success of combination antiretroviral therapy for HIV-1 infection has generated interest in mechanisms by which the virus can persist in the body despite the presence of drugs that effectively inhibit key steps in the virus life cycle. It is becoming clear that viral reservoirs established early in the infection not only prevent sterilizing immunity but also represent a major obstacle to curing the infection with the potent antiretroviral drugs currently in use. Mechanisms of viral persistence are best considered in the context of the dynamics of viral replication in vivo. Virus production in infected individuals is largely the result of a dynamic process involving continuous rounds of de novo infection of and replication in activated CD4(+) T cells with rapid turnover of both free virus and virus-producing cells. This process is largely, but not completely, interrupted by effective antiretroviral therapy. After a few months of therapy, plasma virus levels become undetectable in many patients. Analysis of viral decay rates initially suggested that eradication of the infection might be possible. However, there are several potential cellular and anatomical reservoirs for HIV-1 that may contribute to long-term persistence of HIV-1. These include infected cell in the central nervous system and the male urogenital tract. However, the most worrisome reservoir consists of latently infected resting memory CD4(+) T cells carrying integrated HIV-1 DNA. Definitive demonstration of the presence of this form of latency required development of methods for isolating extremely pure populations of resting CD4(+) T cells and for demonstrating that a small fraction of these cells contain integrated HIV-1 DNA that is competent for replication if the cells undergo antigen-driven activation. Most of the latent virus in resting CD4(+) T cells is found in cells of the memory phenotype. The half-life of this latent reservoir is extremely long (44 months). At this rate, eradication of this reservoir would require over 60 years of treatment. Thus, latently infected resting CD4(+) T cells provide a mechanism for life-long persistence of replication-competent forms of HIV-1, rendering unrealistic hopes of virus eradication with current antiretroviral regimens. The extraordinary stability of the reservoir may reflect gradual reseeding by a very low level of ongoing viral replication and/or mechanisms that contribute to the intrinsic stability of the memory T cell compartment. Given the substantial long-term toxicities of current combination therapy regimens, novel approaches to eradicating this latent reservoir are urgently needed.

Sulfated polysaccharides are potent and selective inhibitors of various enveloped viruses, including herpes simplex virus, cytomegalovirus, vesicular stomatitis virus, and human immunodeficiency virus.

Abstract: Several sulfated polysaccharides (dextran sulfate, pentosan polysulfate, fucoidan, and carrageenans) proved to be potent inhibitors for herpes simplex virus, human cytomegalovirus, vesicular stomatitis virus, Sindbis virus, and human immunodeficiency virus. They were moderately inhibitory to vaccinia virus but not inhibitory to adenovirus, coxsackievirus, poliovirus, parainfluenza virus, and reovirus. These results indicate that, with the exception of parainfluenza virus, enveloped viruses are specifically susceptible to the inhibitory activity of sulfated polysaccharides.

Production of recombinant adeno-associated virus vectors

Abstract: Simplified methods to produce recombinant adeno-associated virus (rAAV) vectors are described. The methods involve the use of chimeric plasmids which incorporate the Epstein Barr nuclear antigen (EBNA) gene, the latent origin of replication of Epstein Barr virus (oriP), and a rAAV genome. The chimeric plasmids themselves are also a part of the present invention. These plasmids are maintained as multicopy extra-chromosomal elements in cells, such as human 293 cells. Permanent cell lines carrying these EBV/AAV plasmids are induced to produce large amounts of rAAV upon addition of wild-type, adeno-associated virus helper functions. Vectors produced in this manner are capable of transducing exogenous genes into other human cell lines and exhibit the attributes of vital elements produced by conventional methods.