Persistent viruses

Bystander activation activation of autoreactive cells through nonspecific inflammation and induction of inflammatory cytokines and chemokines is also of pathological consequence in MS. It has been suggested that bystander activation, induced by persistent virus infection or primed by molecular mimicry may activate autoreactive T-cells specific for the CNS (McCoy et al., 2006). Einally, cryptic antigens may also play a role in immune activation. In other immune-mediated diseases such as Chronic Lymphocytic Thyroiditis and Chagas Heart Disease, exposure of cryptic epitopes leads to the activation of autoimmune cells and further contributes to... 

Long-term feeding bioassays (>72 h.) showed that 23 had a negative effect on the aphid s reproduction (table 9), without associated adult mortality [34], These results point out the potential that this bisabolene has for the control of plant virus transmission by non-persistent viruses (International Patent no. 9602748). 

Ludwig, H., Bode, L., and Gosztonyi, G. 1988. Boma disease A persistent virus infection of the central nervous system. Prog. Med. Virol. 35, 107-151. 

What are the mechanisms of brain dysfunction in persistent virus infection in the brain Probably the most common mechanism of brain injury is a consequence of the immunopathology mediated by the persistent virus. While some of this immun-opathology is antiviral, it may also be in part autoimmune in nature. The inflammation causes the release of leucotrines, prostaglandins, thromboxanes and lymphokines, which interfere with normal brain activity and cause brain degeneration. Gradually, patients succumb to progressive decline in mentation and other neurological dysfunctions. 

Understanding the direct responses of IFNs in virally infected cells may also explain the limited benefit of IFN therapies. For example, it is hypothesized that HBV terminal protein decreases the efficacy of IFN therapy and antagonizes infected hepatocyte antigen presentation to cytotoxic T lymphocytes (Foster et al. 1991). Moreover, IFN-a monotherapy for HCV infection clears persistent virus in only a small fraction of patients. 

Peleg, J., 1969, Inapparent persistent virus infection in continuously grown Aedes aegypti mosquito cells, J. Gen. Virol. 5 463. 

Human Immunodeficiency Virus. Human immunodeficiency vims (HIV) causes Acquired Immunodeficiency Syndrome (AIDS), which has no cure. HIV infects the cells of the human immune system, such as T-lymphocytes, monocytes, and macrophages. After a long period of latency and persistent infection, it results in the progressive decline of the immune system, and leads to full-blown AIDS, resulting in death. 

A major limitation in the development of anti-HCV compounds was the lack of a virus replication system. This was finally overcome with the development of a novel replicon system that directed persistent replication in a cell culture format (Lohmann et al. 1999). Using such a system, it was possible to demonstrate antiviral activity of an NS3/4A inhibitor in a cell culture assay, and demonstrate potency on par with treatment with interferon-a (Pause et al. 2003). 

Abstract In 2007, the world celebrated the 50th anniversary of the discovery of interferon (IFN) by Isaacs and Lindemnann. Subsequently, the IFN-a gene was cloned, fully sequenced and IFN-a was produced in recombinant form. Recombinant IFN-a is now used as the basis for treatment of chronic hepatitis C virus infection and can also be used to treat certain forms of chronic hepatitis B virus infections. IFNs have also been used in other viral infections, although with less success. The antiviral mechanisms of IFNs are reviewed in this chapter as well as the utility of IFNs in the treatment of persistent viral infections. 

The small adeno-associated virus (AAV) vectors can be easily prodnced, have not been found to canse major toxicity, and persist in the transduced hepatocyte typically as an episomal transcriptionally active DNA molecule. Because of the limited packaging capacity for foreign DNA of 4.6 kb, these vectors have been preferentially nsed to express small transgenes and shRNAs directed against HBV or HCV... 

Epstein-Barr virus (EBV) Enveloped, icosahedral particles 150nm in diameter Infections occur by salivary exchange. In young children they are commonly asymptomatic but the virus persists in a latent form in lymphocytes. Infection delayed until adolescence often results in glandularfever. In tropical Africa, a severe EBV infection early in life predisposes the child to malignant facial tumours (Burkitt s lymphoma)... 

Chemical treatment of drinking water and food wash waters can also be used to reduce the presence of infectious NoV. Washing can remove 1-3 logs of FCV or MNV from fruits and vegetables (Baert et ah, 2008b Butot et ah, 2008), although the viruses then persist in the wash water... 

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