OKÜLT HEPATİT B VİRUS ENFEKSİYONU: MOLEKÜLER MEKANİZMALAR VE KLİNİK ÖNEMİ

Öz

Okült Hepatitis B Virüs (HBV) infeksiyonu (OBİ) serum HBV DNA statüsü dikkate alınmaksızın mevcut serolojik testler ile HBV yüzey antijeni (HBsAg) negatif tespit edilen bireylerin karaciğerin de HBV genomunun uzun süreli persistan varlığı olarak tanımlanır. OBİ virüse ve infekte bireye ait faktörler ile çevresel faktörlerin zemininde gelişen genetik, epigenetik ve immünolojik mekanizmaların karşılıklı etkileşimi ile şekillenen, HBV infeksiyonunun doğal seyri içerisinde yer alan muhtemel safhalarından biri olarak kabul edilir. OBİ klinik açıdan; okült virüsün kan transfüzyonu, doğum, hemodiyaliz ve ortotopik karaciğer gibi organ nakli yolu ile bulaşını takiben alıcıda tipik yeni HBV infeksiyonuna neden olabilmesi, immünsüpresyon koşullarında OBİ reaktivasyonu ve takiben HBV ilişkili (akut ve fulminan hepatit) karaciğer hastalıkları, kronik karaciğer hastalıklarının (KKH) progresyonu üzerine etkisi ile özellikle hepatoselüler karsinoma (HSK) için artan bir risk faktörü olduğu yönünde hipotez uyarınca yoğun bir tartışma ve araştırma konusudur. Buna karşın gerek HBV infeksiyonunun bu özgün formuna neden olan gerekse ilişkili olduğu karaciğer hastalıklarının patogenezinde rol alan moleküler mekanizmalar henüz tam olarak aydınlatılamamıştır. Bu derlemede OBİ’nin klinik önemi, epidemiyolojik özellikleri ve laboratuar tanısına yönelik bilimsel literatürün gözden geçirilmesi amaçlanmıştır.

Anahtar Kelimeler: Hepatit B virüs; okült hepatit B virüs infeksiyonu; bulaş; reaktivasyon; kronik karaciğer hastalığı; hepatoselüler karsinoma.

Anahtar Kelimeler

• Hepatit B virüs,okült hepatit B virüs infeksiyonu,bulaş,reaktivasyon,kronik karaciğer hastalığı,hepatoselüler karsinoma

OCCULT HEPATITIS B VIRUS INFECTION: MOLECULAR MECHANISMS AND CLINICAL SIGNIFICANCE

Öz

Occult Hepatitis B Virus (HBV) infection (OBI) is defined as the long-lasting persistence of HBV genomes in the hepatocytes of individuals testing negative for HBV surface antigen (HBsAg) by currently available assays and usually for serum HBV DNA. OBI is considered as the possible phase in the natural history of chronic HBV infection that the host’s immune surveillance and epigenetic mechanisms are likely involved. Clinical impact of OB is that it can be transmitted (i.e., through blood transfusion, by liver organ transplantation, hemodialysis and parturition) causing classic forms of hepatitis B in newly infected individuals. The development of an immunosuppressive status may induce OBI reactivation and development of acute and often severe hepatitis. OBI can favor the progression of liver fibrosis. Also OBİ infection has been hypothesized to be a significant risk factor contributing to the progression of chronic liver diseases (CLD) with increased risk for hepatocellular carcinoma (HCC) which may lead to an increased progression of liver diseases. Although OBI is considered a phase in the natural history of HBV, the molecular mechanisms leading to its occurrence and its contribution to HCC development are yet poorly understood. In this review, it is aimed to examine clinical importance, epidemiological aspects and laboratory diagnosis of OBI in recent literature.

Keywords: Hepatitis B virüs; occult hepatitis B virus infection; transmission; reactivation; chronic liver disease; hepatocellular carcinoma.

Anahtar Kelimeler

• Hepatitis B virüs,occult hepatitis B virus infection,transmission,reactivation,chronic liver disease,hepatocellular carcinoma

Kaynakça

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