Viruses classes

They are coccoid-shaped organisms and the feature which at one time consigned them to the virus class was the fact that they would only reproduce in living tissue. 

The major histocompatibility complex (MHC) is, in fact, a set of genes which code for three classes of proteins -class I, class II and class III. The class I proteins are involved in identifying cells that are infected with a virus. Class II proteins are involved in the interactions between Th cells and antigens. Class III proteins are the complement proteins. Although the name major histocompatibility complex actually refers to the genes,... 

Virus (virus class) Protein name Similar to human chemokine(s) Target or function... 

Since most immortalized cell lines have been shown to express endogenous retro-virus-like particles that may or may not be replication-competent and infectious, and other virus classes may also be present in mammalian cells, the risk for a virus contamination of the end product is inherent. In addition, adventitious vimses may come into contact with the product during processing. In any case, cell culture processes must demonstrate the robust and rehable abihty to eliminate viruses in a risk-based approach [162] (see Part IV, Chapter 1). Vims validation studies employ model vimses that are relevant in representing known risks from the sources involved [163, 164]. 

Stern, L.J., Brown, J.H., Jardetzky, T.S., Gorga, J.C., Urban, R.G., Strominger, J.L., Wiley, D.C. Crystal structure of the human class 11 MHC protein HLA-DRl complexed with an influenza virus peptide. Nature 368 215-221,... 

Antiparallel tt-helix proteins are structures heavily dominated by a-helices. The simplest way to pack helices is in an antiparallel manner, and most of the proteins in this class consist of bundles of antiparallel helices. Many of these exhibit a slight (15°) left-handed twist of the helix bundle. Figure 6.29 shows a representative sample of antiparallel a-helix proteins. Many of these are regular, uniform structures, but in a few cases (uteroglobin, for example) one of the helices is tilted away from the bundle. Tobacco mosaic virus protein has small, highly... 

Neuraminidase inhibitors are the major class of drugs to treat or to prevent the infection with influenza viruses. Currently, two neuraminidase inhibitors are available, zanamivir and oseltamivir, which block the release of new influenza vims from infected host cells and thereby stop the spread of infection. The enzyme neuraminidase is a surface glycoprotein present on all influenza viruses. There are nine influenza neuraminidase sub-types known of which subtypes N1 and N2 appear to be the most important ones. Neuraminidase inhibitors are effective against all neuraminidase subtypes. The activity of the neuraminidase is required for the newly... 

Fig. 1 Classification of viruses by their genome replication strategy according to Baltimore (Baltimore 1971), Examples for important human pathogens falling into the respective class are listed above, Black DNA, gray RNA arrows to the right (+) strand polarity (i,e, corresponding to mRNA) arrows to the left (—(strands asterisk enveloped viruses...

However, acyclic nucleotide analogs (acyclic nucleoside phosphonates) have been developed, which carry one phosphonate moiety and require only the two subsequent phosphorylation steps (De Clercq et al. 1978). Independent of virus-encoded kinases, they display a broader spectrum of efficacy. This class comprises important drugs against HIV (tenofovir) and HBV (adefovir, tenofovir), as well as cidofovir, which is approved for use against CMV retinitis, but also displays an exceptionally broad efficacy profile against many herpesviruses, adenovirus, poxviruses, and papillomaviruses (De Clercq and Holy 2005). 

Structural analysis of the rhinovirus and the hepatitis A virus 3C proteases (Allaire et al. 1994 Matthews et al. 1994) confirmed earlier predictions that the picomavirus 3C proteases are similar to chymotrypsin-Uke serine proteases in their fold. An important difference is that the serine nucleophile of serine proteases is replaced with a cysteine however, the 3C protease is stracturally distinct from the eukaryotic cysteine protease class of enzymes. 

Zhang J, Yu K, Zhu W, Jiang H (2006) Neuraminidase pharmacophore model derived from diverse classes of inhibitors. Bioorg Med Chem Lett 16 3009-3014 Ziircher T, Yates PJ, Daly J, Sahasrabudhe A, Walters M, Dash L, Tisdale M, McKimm-Breschkin JL (2006) Mutations conferring zanamivir resistance in human influenza virus N2 neuraminidases compromise virus fitness and are not stably maintained in vitro. J Antimicrob Chemother 58 723-732... 

The first lead compounds for non-nucleoside reverse transcriptase (RT) inhibitors (NNRTl) were discovered about 15 years ago (Pauwels et al. 1990 Merluzzi et al. 1990 Goldman et al. 1991 De Clercq 1993 Riibsamen-Waigmann et al. 1997). Since then they have become an important ingredient of the dmg combination schemes that are currently used in the treatment of human immunodeficiency virus type 1 (HlV-1) infections. Starting from the HEPT and TIBO derivatives, numerous classes of compounds have been described as NNRTIs. Four compounds (nevirapine, delavirdine, efavirenz and etravirine) have so far been approved for clinical use and several others are the subject of clinical trials (Balzarini 2004 Stellbrink 2007). 

T-1249 demonstrated substantial activity against enfuvirtide-resistant viruses in clinical studies (Melby et al. 2007a) however, development was discontinued due to formulation issues. Additional peptides with more potent activity were subsequently designed, which also showed much improved pharmacokinetic properties (Dwyer et al. 2007) however, the availability of oral agents in other new classes makes the likelihood of the development of these agents uncertain. 

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