Hepatit C Virüsü
Özet
Hepatit C virüsü (HCV), pozitif kutuplu ve tek iplikli bir RNA virüsü olup, siroz ve hepatoselüler karsinom gibi ilerleyici karaciğer hasarlarına yol açabilen küresel bir sağlık sorunudur. Viral genomdaki yüksek heterojenite ve RNA polimeraz enziminin tamir fonksiyonunun olmaması, mutant virüslerin oluşmasına ve tedavi başarısının düşmesine neden olmaktadır. Dünyada en sık genotip 1 görülürken, Türkiye'de prevelans %0,6-0,8 civarındadır ve en yaygın alt tip ağır seyirli genotip 1b'dir. Bulaşma yolları ağırlıklı olarak parenteral olup, tanı sürecinde ilk olarak anti-HCV taraması ve ardından kesinlik için niceleyici HCV-RNA ölçümü uygulanmaktadır. Akut enfeksiyonların %55-85'i kronikleşme eğilimi gösterirken, hastalık asemptomatik veya silik semptomlarla ilerleyerek ciddi karaciğer yetmezliğine ve çeşitli ekstrahepatik komplikasyonlara zemin hazırlayabilmektedir. Günümüz kronik hepatit C tedavisinin temel amacı, tedaviden 12 hafta sonra serumda virüsün saptanamaması anlamına gelen kalıcı viral yanıt (KVY) elde etmektir. Son yıllarda geliştirilen direkt etkili antiviraller (DEA); NS3/4A proteaz, NS5A ve NS5B inhibitörleri sayesinde yan etkileri azaltmış, tedavi sürelerini kısaltmış ve KVY başarı oranını %99 gibi oldukça yüksek bir seviyeye ulaştırmıştır.
Hepatitis C virus (HCV) is a positive-sense, single-stranded RNA virus from the Flaviviridae family that causes progressive liver damage, potentially leading to cirrhosis and hepatocellular carcinoma. Due to the lack of proofreading activity in its RNA-dependent RNA polymerase enzyme, the virus exhibits significant genomic heterogeneity, which results in mutant strains and contributes to lower treatment responses. Nationally and globally, genotype 1 is the most prevalent, with subtype 1b being the most dominant and aggressive form in Turkey, carrying a higher risk of chronicity and low response to older interferon therapies. Transmission occurs primarily through parenteral routes, and diagnosis relies on anti-HCV antibody screening followed by quantitative HCV-RNA testing for confirmation. While a small percentage clears the virus spontaneously, approximately 55-85% of cases progress to chronic infection, which often remains asymptomatic until severe stages like decompensated cirrhosis manifest. The primary goal of modern management is achieving a sustained virological response (SVR) 12 weeks post-treatment. The advent of direct-acting antivirals (DAAs), including NS3/4A protease, NS5A, and NS5B inhibitors, has revolutionized the therapeutic landscape, shortening treatment duration, minimizing adverse effects, and raising SVR success rates up to 99%.
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