Molecular Characterization of HPV-16 L1 gene

Abstract

Human papillomavirus (HPV) is the most common cause of sexually transmitted infections in the world. HPV is responsible for the development of virtually all cervical cancer cases. In addition to that there is mounting evidence showing its possible involvement in cancers other than cervix. The currently available prophylactic vaccines are based on the self-assembling property of the major capsid protein encoded by L1 gene. The high cost associated with these vaccines prevents their use in most developing countries. Therefore, the current aims of the study involved HPV screening of various paraffin embedded cancer samples, followed by molecular characterization of L1 gene with an aim to predict epitopes for the future development of subunit vaccine in Pakistan. These objectives were achieved by using PCR and in-silico approaches. General primers (GP) and type specific primers (TS16, TS18) were used to amplify a conserved region in L1 and E6 gene. The sensitivity of type specific primers was found to be better than the GP. With the use of GP, HPV was detected in about 50% cases while TS primers revealed 75% of HPV positive cases. Single infection of HPV16 involved in 64.5% cases and about 27.7 % of cases positive for HPV-18 and in 21% of cases co-infections of both types of HPV. A strong association of HPV-16 with cancers other than that of cervix was also found. The amplification of L1 gene particularly from the formalin fixed paraffin sections (FFPE) have been challenging, however the limited number of samples exhibited