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Studies on viral infections by hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis delta virus (HDV) and GB virus C (GBV-C) in different regions of South America

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Author(s):
Monica Viviana Alvarado Mora
Total Authors: 1
Document type: Doctoral Thesis
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD)
Defense date:
Examining board members:
João Renato Rebello Pinho; Flair José Carrilho; Nelson Jurandi Rosa Fagundes; Elisabeth Lampe; André Castro Lyra
Advisor: João Renato Rebello Pinho
Abstract

Viral hepatitis are among the major pandemics in the world nowadays. There are many causes of hepatitis, including hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis delta virus (HDV). Similarly, GB virus C (GBV-C) is a relevant agent in co-infection with HIV. In this study, several regions of South America were studied. In Colombia, the states of Amazonas and Magdalena were identified as highly endemic areas for HBV. Genotype F3 (75%) was the most prevalent. It was determined that subgenotype F3 is the oldest among all F subgenotypes. In the state of Chocó, subgenotype A1 (52.1%) was the most prevalent. Surprisingly, nine indigenous cases of infection by genotype E (39.1%) were found in this state. For HCV, in Bogotá, subtype 1b (82.8%) was the most frequent. Likewise, it was estimated that this subtype was introduced around 1950 and spread exponentially from 1970 to 1990. HDV has been identified in cases of fulminant hepatitis in the state of Amazonas, all of them classified as genotype 3. It was determined that the HDV/3 spread exponentially from 1950 to 1970 in South America and after this time, this infection stopped to increase, probably due to introduction of vaccination against HBV. GBV-C was sought in Colombian blood donors infected with HCV and/or HBV in Bogotá and indigenous peoples with HBV infection in the Amazon. The phylogenetic analysis revealed the presence of genotype 3 as the most prevalent among blood donors and in three studied indigenous people. The presence of genotype 3 in the indigenous population has been previously reported in the region of Santa Marta, Colombia, and in the indigenous peoples of Venezuela and Bolivia. In Chile, a study was carried out with 21 patients chronically infected with HBV without any prior antiviral treatment. All sequences obtained belonged to subgenotype F1b and clustered into four different groups, suggesting that different strains that are circulating in Chile. In Brazil, the state of Rondônia, we found HCV subtype 1b (50.0%) as the most frequent. This was the first report on HCV genotypes in this state. For HBV, subgenotype A1 (37.0%) was the most frequent. The results of the state of Rondônia are consistent with other studies carried out in Brazil, showing the presence of several HBV genotypes, reflecting the mixed origin of the Brazilian population. Studying the state of Maranhão, we evaluated the frequency of HBV infection and its genotypes and we found 4 genotype A1 sequences that grouped with other sequences reported in Brazil. In another study, we characterized HBV subgenotypes in 68 patients with chronic hepatitis B in Pernambuco and we found subgenotype A1 in 78.7% cases. Finally, in a study of samples from São Paulo, we found a case of HBV genotype C in a native Brazilian patient and this is the first complete genome sequence of HBV/C2 reported in Brazil (AU)