Phylogenetic and Phylodynamic Analyses of HCV Strains Circulating among Patients Using Injectable Drugs in Central...

Area of Science:

• Virology
• Epidemiology
• Molecular Biology

Background:

• Hepatitis C virus (HCV) infects approximately 71 million globally.
• Injectable drug use is a primary HCV transmission route in developed nations.
• Understanding HCV molecular epidemiology in vulnerable populations is crucial.

Purpose of the Study:

• To investigate the molecular characteristics of HCV infection among people who use drugs (PWUD) in Italy.
• To identify common HCV genotypes and transmission patterns within this cohort.
• To analyze the population dynamics and evolutionary rates of prevalent HCV genotypes.

Main Methods:

• Analysis of HCV RNA positivity in 208 PWUD.
• Genotyping of HCV strains, with a focus on Gt1a and Gt3a.
• Bayesian phylogenetic and coalescent skyline analyses of HCV NS5B sequences from 66 participants.
• Estimation of evolutionary rates and reproduction numbers.

Main Results:

• HCV RNA was detected in 48.6% of the studied PWUD.
• HCV genotype 1a (47%) was the most prevalent, followed by Gt3a (34.9%).
• Phylogenetic analysis linked closely related strains to age and neighborhood proximity.
• HCV Gt1a showed increased prevalence from the mid-1980s to mid-1990s; Gt3a remained relatively constant initially, with both genotypes showing increased reproduction numbers post-2014.

Conclusions:

• HCV Gt1a and Gt3a are the dominant genotypes among PWUD in Italy.
• Social and demographic factors influence HCV transmission clusters.
• Recent increases in reproduction numbers suggest evolving epidemic dynamics for key HCV genotypes in this population.