Genes of predisposition to herpes

University of Utah scientists have identified a region on the long arm of 21 human chromosomes, with a high probability (at least 1000:1) associated with a predisposition to the formation of herpetic ulcers. Further studies have led to the identification of 6 specific genes in this region, which are the most likely candidates for genes predisposition to manifestations of the herpes simplex virus.

There are 2 types of herpes simplex virus (HSV). Reactivation of the herpes simplex virus type 1 persisting in the nerve endings causes the development of itchy ulcers familiar to many on the red border of the lips, nose and around the mouth, and is also the cause of herpes keratitis – an infectious lesion of the eye, leading to the formation of scars on the cornea and blindness. The vast majority of people around the world are infected with herpes simplex virus type 1, but many do not experience any symptoms of the disease.

Herpes simplex virus type 2 is the main cause of genital herpes. According to statistics, about 17% of the US population (50 million people) are infected with herpes type 2. 5-10 million of them in the group show symptoms of genital herpes.

To search for genes of predisposition to the formation of herpetic ulcers, the authors used a method of analyzing the coupling between gene loci, which allows tracking genetic markers in families to identify regions of chromosomes containing genes of predisposition to the disease. During the transmission of hereditary material from generation to generation, genetic markers located in the immediate vicinity of the altered genes are inherited at the same time.

421 people from 39 large families living in Utah who took part in the Utah Genetic Reference Project genomic study were involved in the work. The participants were divided into 4 groups according to the frequency of occurrence of herpetic ulcers:
1) frequently ill – infected with HSV-1 and carrying 2 or more ulcers annually (89 participants);
2) moderately ill – infected with HSV-1 and carrying 2 or less ulcers annually (111);
3) not experiencing symptoms – infected with HSV-1 and never experienced symptoms (85);
4) uninfected or of unknown status – not subject to classification (146).

For further research, the authors selected only representatives of the 1st and 3rd groups, which provided the most pronounced difference in sensitivity to herpes. According to the results of mathematical analysis of genetic data, the identified region of the long arm of chromosome 21 increases the predisposition to frequent herpetic ulcers by 1000 times.

Probable hereditary predisposition is not the only reason for reactivation of the herpes virus: it is also promoted by well–known external factors – colds, general and local hypothermia, sunburn. The frequency of reactivations, apparently, depends on the virus itself – its strain and the magnitude of the viral load in the body.

Currently, the authors are studying 6 genes that are most likely to provide a predisposition to HSV-1 manifestations. Identification of such genes will allow to develop new methods of treatment of the disease, which is considered practically incurable today. The value of the study will increase many times if its results help in the fight against genital herpes and herpetic keratitis.

Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily.

30.01.2008