Genital Herpes

Only available on StudyMode
  • Download(s) : 154
  • Published : May 13, 2005
Open Document
Text Preview
I have infected 45 million Americans and will infect 1 million more Americans each year. Who am I? Herpes, from the ancient Greek meaning to creep or crawl, is the name of a family of viruses of which herpes simplex virus 1 and herpes simplex virus 2 (HSV-1 and HSV-2) are the most serious human pathogens. HSV-1 is normally associated with orofacial infections and encephalitis, whereas HSV-2 usually causes genital infections and can be transmitted from infected mothers to neonates. Both viruses establish latent infections in sensory neurons and, upon reactivation, cause lesions at or near point of entry into the body. While HSV-1 and HSV-2 are different viruses, under a microscope, HSV-1 and 2 are virtually identical, sharing approximately 50% of their DNA and are treated similarly. HSV-1 and HSV-2 contain a large double-stranded DNA molecule. HSV is gram negative, consists of 162 capsomers and replication takes place within the nuclei of eukaryotic cells. The HSV virion has four parts: an electrondense core containing viral DNA; an icosapentahedral capsid; a tegument-an amorphous layer of proteins that surround the capsid; and an envelope. HSV-1 and HSV-2 encode at least 84 different polypeptides. Each protein does many things, hence HSV genes can encode several hundred different functions. To initiate infection, HSV attaches to at least three different classes of cell-surface receptor and fuses its envelope with the plasma membrane. The capsid, minus its envelope, is transported to the nuclear pore, through which it releases viral DNA into the nucleus. HSV replicates by three rounds of transcription that yield: alpha (immediate early) proteins that mainly regulate viral replication; beta (early) proteins that synthesise and package DNA; and gamma (late) proteins, most of which are virion proteins. Of the 84 known polypeptides, at least 47 are not needed for viral replication in cultured cells. These 47 genes are not completely dispensable. Some complement...
tracking img