Related Experiment Video
Updated: May 31, 2026
Dried Blood Spots - Preparing and Processing for Use in Immunoassays and in Molecular Techniques
Published on: March 13, 2015
Molecular analysis of hepatitis C virus infection in Bulgarian injecting drug users
Massimo Ciccozzi1, Gianni Zehender, Valeria Cento
1Department of Infectious, Parasitic and Immunomediated Disease, Istituto Superiore di Sanita', Rome, Italy.
Insights
Hepatitis C virus (HCV) genotype 3a is most common among Bulgarian intravenous drug users. Molecular clock analysis reveals the HCV epidemic in Bulgaria began around 1960, with significant growth until the 2000s.
Area of Science:
- Epidemiology
- Virology
- Molecular Biology
Background:
- Intravenous drug users (IDUs) are at high risk for Hepatitis C virus (HCV) infection.
- Limited data exists on HCV molecular epidemiology in Bulgaria, despite rising incidence among IDUs.
- Two-thirds of infected Bulgarian IDUs develop chronic HCV infection.
Purpose of the Study:
- To determine the prevalence of HCV genotypes among Bulgarian IDUs.
- To investigate the evolutionary history and transmission dynamics of HCV in Bulgaria using molecular methods.
Main Methods:
- Sequencing of the NS5B gene of the HCV virus.
- Phylogenetic analysis using molecular clock and Bayesian inference methods.
Main Results:
- Hepatitis C virus (HCV) genotype 3a was the predominant strain among Bulgarian IDUs.
- Bayesian phylogenetic analysis dated the origin of the Bulgarian HCV 3a clade to 1960.
- The HCV epidemic in Bulgaria experienced exponential growth from the 1960s to the 1990s, plateauing in the 2000s.
Conclusions:
- HCV genotype 3a is the primary circulating strain among Bulgarian IDUs.
- The findings provide insights into the historical spread and evolution of HCV in Bulgaria.
- The observed epidemic plateau may suggest the impact of public health interventions in Bulgaria.
Abstract:
Intravenous drug users constitute a group at risk for hepatitis C virus (HCV) infection. Today, no data are available on the molecular epidemiology of HCV in Bulgaria despite the fact that in recent years the incidence of acute hepatitis C infection among Bulgarian intravenous drug users increased sixfold and about 2/3 of them developed a chronic infection. The aim of this study was to determine the circulation of hepatitis C genotypes among drug users and to study the evolution and transmission history of the virus by molecular clock and Bayesian methods, respectively. Sequencing of NS5B gene showed that the genotype 3a was the most prevalent type among intravenous drug users. In the Bayesian tree, the 3a subtypes grouped in one main clade with one small cluster well statistically supported. The root of the tree was dated back to the year 1836, and the main clade from Bulgaria was dated 1960. The effective number of infections remained constant until about years 1950s, growing exponentially from the 1960s to the 1990s, reaching a plateau in the years 2000. The not significant intermixing with isolates from other countries may suggest a segregated circulation of the epidemic between 1940s and 1980s. The plateau reached by the epidemic in the early 2000s may indicate the partial success of the new preventive policies adopted in Bulgaria.
Related Concept Videos
01:25Hepatitis
01:28Viral Hepatitis I: Introduction