Hepatitis C virus Infection: Innate and adaptive immunity, risk factors, genotypes and prevalence in Nigeria – A systematic Review

Background:  HCV burdens Nigeria with chronic infections, influenced by genotypes (1, 2, 3) and evasive immune responses. Tailored strategies are crucial. Aims and Objective: This review examined HCV in Nigeria, emphasizing immunity, risk factors, genotypes, and prevalence. Methodology: A comprehensive search was conducted across electronic databases, including PubMed, Scopus, Web of Science, Springer Nature/Nature and online African Journals. The following keywords were used: "Hepatitis C Virus," "HCV," "innate immunity," "adaptive immunity," "genotypes," "prevalence," "Nigeria," and related term. Inclusion criteria encompassed Nigerian studies on immunity, genotypes, and prevalence. Extracted data included study specifics, demographics, methods, and prevalence were assessed using quality tools. Findings were synthesized to uncover immune responses, genotypes, and prevalence patterns. Findings: Transmission risk factors in Nigeria encompass blood transfusion, injection drug use, healthcare exposure, tattooing, sexual contact, HIV, and HBV co-infections. HCV prevalence ranges from 2.2% to 24.2%. Genotype 1 dominates, particularly subtypes 1a and 1b, with genotypes 2, 3, 4, 5, and 6 also present. HCV's evasion tactics hinder innate and adaptive immunity responses. In Nigeria, HCV infection is a significant health burden. The prevalence of Hepatitis C Virus (HCV) genotypes in Nigeria varies, with genotype 1 being the most prevalent at 64.7%, followed by genotypes 3, 2, 4, and 6 at 7.4%, 5.9%, 4.4%, and 2.9% respectively. Genotype 5 was found to be absent in the studied cohorts. Nigeria has identified genotypes 1, 3, 2, 4, and 6, with genotype 1 being the most prevalent at 64.7%  Research gaps include limited immune profiling, genotype-host dynamics understanding, immune interventions scarcity, and data integration absence. Co-infection impacts and regional prevalence variations necessitate further exploration. Addressing these gaps is crucial for a holistic comprehension of HCV in Nigeria, guiding effective strategies. Globally, HCV prevalence varies from 1.7% to 13.8% with around 62 million affected by chronic HCV in 2019. Innate and adaptive immune responses are pivotal for controlling HCV. Conclusion: This review offers a comprehensive understanding, bridging knowledge gaps, and influencing evidence-based interventions to combat HCV in Nigeria.