Evolución del virus de la hepatitis C en muestras hospitalarias de la Comunidad Valenciana
Hepatitis C virus is present in 2% of the human population. It is characterised, phylogenetically, by the presence of a number of major genotypes, with a star-like phylogenetic distribution, and composed by several minor subtypes. The most abundant genotype in Europe is called 1, with two prevailing subtypes, 1a and 1b. In order to explain the higher prevalence of subtype 1b over 1a, we have carried out several large-scale sequence analysis, such as: analysis of polimorphisms, analisys of variance inference of demographic history, neutrality test and search of amonoacidical positions under positive selection. Two regions have been used for this task: one compressing the HVR1 (hypervariable region 1) and other including ISDR (Interferon sensitive determinig region) from 100 viral clones of each one of 25 patients subtype 1a and 25 1b, from the Comunidad Valenciana (Spain).
Neither analysis of polimorphisms nor analysis of variance showed differences between subtypes, only the demographic history of the populations reflected some relation with regard to the route of transmission. By other hand we have found several positions in HVR1 under positive selection that coincide in both subtypes, therefore this situation neither explain difference in prevalence. Nevertheless the presence of mutations due to positive selection, could be indicating a mechanism of virus to scape from de attack of immune system. In contrast we observe the absence of positive selection in region ISDR. This absence could be favoring the resistance to interferon and the viral replication. This last situation is similar in both subtypes too.
Therefore and in general, our results showed that route of transmission could be the cause of the highest prevalence of subtype 1b over 1a.
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Advisor:Moya Simarro, Andres
School:Universitat de València
Source Type:Master's Thesis
Date of Publication:07/23/2004