Viruses penetration

What is the function of the membrane in a virus particle We will discuss this in detail later but note that because of its location in the virion, the membrane is the structural component of the virus particle that interacts first with the cell. The specificity of virus infection, and some aspects of virus penetration, are controlled in part by characteristics of virus membranes. 

Infection begins when specific receptor sites on the virus recognize corresponding surface proteins on the host cell. The virus penetrates the host membrane by a mechanism resembling endocytosis and is encapsulated... 

Soyasaponin I and II were studied in vitro against herpes simplex virus type I (HSV-1). Soyasaponin II was more potent than soyasaponin I in the reduction of HSV-1 production. Soyasaponin II was also found to inhibit the replication of human cytomegalovirus, influenza virus, and human immunodeficiency virus type 1. This activity was not due to the inhibition of virus penetration and protein synthesis, but might involve a virucidal effect. When acyclovir and soyasaponin II were evaluated in combination for anti-HSV-1 activity, additive antiviral effects were observed for this virus [160]. Astragaloside II afforded almost 100% protection of T-lymphocytes in vitro against the cytophatic effects of HIV infection. However, the EC50 of ca. 2.5 x 105 molar was difficult to achieve in vivo [98],... 

When a virus penetrates a cell instead of causing a productive infection it may transform that cell. For this to happen its genome (or a part of its genome) must integrate into the cellular chromosomes. The site of integration does not appear to be unique and often several copies of the viral DNA are integrated. 

During endocytosis, the association between receptor and anti-receptor draws the cell membrane to engulf the virus particle forming a cytosolic vacuole, similar to the process by which cells ingest other materials. Probably all non-enveloped viruses penetrate the cell in this manner, but some enveloped viruses such as orthomyxoviruses (e.g. influenza) also use this process. 

Antiviral action against influenza A virus believed to prevent uncoating of virus, penetration of host cells, release of nucleic acid into host cells. 

After the virus penetrates the cell membrane, another viral protein, neuraminidase (sialidase), cleaves the glycosidic bonds to the sialic acid residues, freeing the virus to infect the cell. Inhibitors of this enTiyme such as oseltamivir (Tamiflu) and zanamivir (Relenza) are important anti-influenza agents. 

An increasing number of examples are known whereby receptors that recognize neurotransmitters also recognize much larger chemical species, notably viruses, and serve as entry points for virus penetration into the cell. Among the most widely studied such systems in recent years are the CD4 and chemokine receptors with which the HIV-1 and HIV-2 viruses interact with terminal consequences. A number of specific examples are given in Table 1. 

CD Lytle, WH Cyr, RE Carey, DG Shombert, BA Herman, et al. Standard quality control testing and virus penetration. In GA Mellsrom, JE Wahlberg, HI Maibach, eds. Protective Gloves for Occupational Use. Boca Raton, EL CRC Press, 1994, pp. 109-127. 

Relatively few clinically useful drugs have been developed for viral infections. The slow progress of this endeavor is due to the nature of viruses and the way they replicate. Viruses are smaller than bacteria and consist of nucleic acid—either DNA or RNA—surrounded by a coat of protein. Some viruses penetrate the host cell others merely inject their nucleic acid into the cell. In either case, the viral nucleic acid is transcribed by the host and is integrated into the host genome. 

ABILITY OF QUALITY ASSURANCE TESTS TO DETECT PUNCTURED LATEX CONDOMS WITH POTENTIAL FOR VIRUS PENETRATION... 

Defective condoms were created by puncturing with small acupuncture needles and were then tested by three quality assurance tests (the water leak test, a proposed electrical test, and the air burst) and by a virus penetration test. 13 refs. 

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