Hepatitis B Virus Genotype D Isolates Circulating in Chapecó, Southern Brazil, Originate from Italy

Abstract

Hepatitis B virus genotype A1 (HBV/A1), of African origin, is the most prevalent genotype in Brazil, while HBV/F predominates in the other South American countries. However, HBV/D is the most common in the three states of southern Brazil, where ‘islands’ of elevated prevalence, as Chapecó and other cities, have been described. In this study, 202 HBV chronic carriers attending in 2013 the viral hepatitis ambulatory of Chapecó, were investigated. In comparison with previous studies performed in the same ambulatory, a rapid aging of the HBV infected population was observed (mean age of the newly diagnosed patients increasing from 29.9 ± 10.3 years in 1996 to 44.4 ± 13.3 years in 2013), probably due to a singular vaccination schedule at Chapecó that included not only children but also adolescents. Phylogenetic and BLAST analyses (S region) classified 91 HBV isolates into genotypes A (n = 3) and D (n = 88). The majority of HBV/D isolates were closely related to D3 sequences. To understand the reasons for the absence or near absence of genotypes A and F, and how HBV/D was introduced in the south of Brazil, HBV/D infected patients were inquired about their genealogical and geographical origins. Forty-three (52%) patients have their four grandparents of Italian origin, vs. seven (8%) who have their four grandparents of Brazilian origin. At all, 65 out of 83 (78%) patients had at least one grandparent originating from Italy. Taking into consideration the fact that Italy is one of the few countries where subgenotype D3 is predominant, the results strongly suggested that HBV/D was introduced in Brazil through Italian immigration which culminated between 1870 and 1920.

Risk factors for hepatitis B transmission in South Brazil

“…HBV infection is one of the important health problems in Brazil. In South Brazil, recent data indicate that a prevalence rate higher than the average occurs in some cities and regions ( Bertolini et al 2012 , Gusatti et al 2015 ). Caxias do Sul is one of these cities, with 1.6% population positive towards HBsAg ( Menegol & Spilki 2014 ).…”

“…In contrast, the southernmost regions have a low HBV prevalence, but the states of Santa Catarina and Paraná were reported to have moderate to high endemicity ( Souto 2016 ). Previous studies have also demonstrated that some specific populations (Italian descendants) contribute to high hepatitis B rates in some regions and cities of South Brazil ( Bertolini et al 2012 , Gusatti et al 2015 ).…”

Association between cytokine gene polymorphisms and outcome of hepatitis B virus infection in southern Brazil

“…Another relevant characteristic of the present study was its uniformity in terms of viral genotype. Indeed, it has been previously shown that >95% of the HBV isolates circulating in Chapecó belonged to the same genotype (D) [Gusatti et al, ]. This was a great advantage compared to other studies in which the HBV genotypes involved were not determined or where the patients were infected with different genotypes, which introduced a supplementary variable and might hamper the interpretation of the results.…”

“…Blood samples were collected from 345 adults living in Chapecó, state of Santa Catarina, southern Brazil, who were divided into two groups. Group 1 consisted of 196 HBV chronically infected patients attending a viral hepatitis ambulatory [Gusatti et al, ]. One hundred and thirty‐six (69.4%) of them were asymptomatic carriers, 59 (30.1%) were patients with chronic active hepatitis B without cirrhosis, and the remaining one (0.5%) was a cirrhotic patient.…”

“…All participants knew to be or have been infected with HBV, gave their written consent to participate to the study, and answered questions about demographic and epidemiological features [Gusatti et al, ]. Participants were classified as whites, blacks and mulattos by self‐identification.…”