Ubiquitous viruses

Abstract This review provides an overview of the development of viral protease inhibitors as antiviral drugs. We concentrate on HlV-1 protease inhibitors, as these have made the most significant advances in the recent past. Thus, we discuss the biochemistry of HlV-1 protease, inhibitor development, clinical use of inhibitors, and evolution of resistance. Since many different viruses encode essential proteases, it is possible to envision the development of a potent protease inhibitor for other viruses if the processing site sequence and the catalytic mechanism are known. At this time, interest in developing inhibitors is Umited to viruses that cause chronic disease, viruses that have the potential to cause large-scale epidemics, or viruses that are sufQciently ubiquitous that treating an acute infection would be... 

The c-myc gene, identified originally as the cellular homolog of the transforming determinant carried by avian myelocytomatosis virus, is altered in association with a broad spectrum of neoplasms. Consistent with the observation that altered c-myc is associated with tumors of diverse origin, it has been observed that normal c-myc is expressed in a variety of tissues. Thus, c-myc appears to encode a function associated with a ubiquitous metabolic pathway. 

Human cytomegalovirus (HCMV) is a ubiquitous member of the herpes virus family. Although most infections are asymptomatic, severe manifestations of HCMV can be seen in individuals whose immune system has been weakened by... 

In contrast to antibacterial antibiotic therapy, inhibition of viral replication is usually difficult to achieve. Therefore preventive strategies, such as vaccination, are frequendy more successful and clinically important. However, vaccines are not available for all viruses furthermore, some viruses, such as Epstein-Barr virus (EBV) and cytomegalovirus (CMV), are ubiquitously present and usually not very pathogenic unless in an immunocompromised host. One strategy to combat viral infecdons in the immunocompromised host is the application of neutralizing mAbs. One such mAh is directed to the F protein of the respiratory syncytial virus (RSV), which afflicts premature newborns with often severe pulmonary infections this mAh appears to be useful in such situations (91). Other mAbs to viral antigens are in development. 

Zhang et al, 1999). The layers of dsRNA have also been detected by SAXS (Harvey et al., 1981). As with BTV and orthoreovirus, a 120-subunit surface forms the first (and here only) layer, a capsid geometry that was previously unknown and that appears to be ubiquitous among reoviruses. The virus is occluded within a crystal of the viral protein polyhedrin (Payne and Mertens, 1983), which dissolves in the alkaline pH of the insect gut, releasing infectious viruses. Occlusion within a robust crystal lattice provides a communal solution to the need for protection provided in other reoviruses by outer viral layers. 

The retroviruses have been the subject of intense study because of the emergence of human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS), and this study has led to a structural understanding of complicated viruses that has been unfolding rapidly. In the immature virus, two copies of (+)ssRNA are surrounded by a spherical immature capsid that contains about 2000 copies of the Gag polyprotein (the precursor of the structural proteins), and up to a few hundred copies of larger polyproteins, the most ubiquitous being Gag-Pol, a polyprotein that in addition contains precursors of the proteinase (PR), reverse... 

TTV can be transmitted by blood products and through common parenteral routes (560, 563, 564) as well as by haemodialysis. (554, 556) TTV could also be detected in umbilical cord blood, so that a neonatal (in utero) transmission is to be considered. (558) The likelihood of enteric transmission has been shown by the finding of TTV DNA in breast milk, saliva, duodenal fluid, bile juice and faeces. There is a higher viral load in saliva than in the corresponding serum. (555,566) TTV displays ubiquitous diffusion in human tissue and is able to invade the central nervous system. (562) A high virus load has been demonstrated in patients with HCV-associated HHC. (568) Although TTV has been found in patients with a broad range of liver diseases, current... 

Pollicino, T., Raffa, G., Squadrito, G., Constantino, L., Cacciola, I., Brancatelli, S., Alafaci, C., Florio, M.G., Raimondo, G. TT virus has a ubiquitous diffusion in human body tissues analyses of paired serum and tissue samples. J. Viral Hepat. 2003 10 95-102... 

Genetic elements of viruses are ubiquitously used in genetic engineering to achieve supranatural expression in organisms. For viral vectors, the production system involves the use of a functional virus. The expression levels achieved by these systems are typically several percent of soluble protein—consistently higher than achieved by chromosomal integration (Table 2). 

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