Hepatitis B virus x gene mutations among HBV infected individuals in southwest Nigeria

Abstract

Despite the availability of efficient vaccines against hepatitis B, it still poses a great public health issue especially in places with less developed healthcare facilities and buoyant economy to cater for the infected and conduct relevant studies that give directions to more efficient prevention and control of the disease. Each ORF of the hepatitis B virus plays key roles in the perpetuation and pathogenesis of the virus but not many studies have been carried out on the X ORF especially in Nigeria. The resulting multifunctional protein which is strongly associated with the development of HCC has not been well studied in Nigeria. The study was, hence, designed to analyze the HBx ORF in sick and asymptomatic HBV carriers in southwest Nigeria. Venous blood samples collected from consenting apparently healthy and sick individuals presenting with fever and mild abdominal discomfort were prescreened for the HBsAg. Samples positive for this marker had their HBV DNA extracted, HBx gene amplified, sequenced, genotyped and their sequences analyzed using appropriate tools. In all,19 HBV isolates were amplified and confirmed to be genotype E. Observed in them all was S123L mutation. Also observed were S62A (4/19; 21.1%) and F73*, T74K, S75V, R77W, and R78C all having 10.5%; 2/19 each. Mutations, I88F and V131I, whose roles in the pathogenesis of hepatitis B have been reported were also observed. Multiple mutations on the N - and C- termini whose association with advanced liver diseases and predisposition to HCC need to be studied were observed in seven (7/19; 36.6%). Individual studies of the HBV ORFs may be necessary, especially in Africa where there seems to be more asymptomatic carriers of HBV for a better understanding of the evolution of the virus which will in-turn enhance the prevention and control of the disease.