Detection of Human Papillomavirus Genotypes and Epstein-Barr Virus in Nasopharyngeal Carcinomas at the Korle-Bu Teaching Hospital, Ghana

Abstract

Nasopharyngeal carcinomas (NPC) are endemic in Far East Asia and commonly harbour Epstein-Barr virus (EBV) which is known to serve as a key oncogenic promoter. Human papillomavirus (HPV) is known to contribute to the pathogenesis of NPC. However, in Ghana these two viruses have not been linked to NPC prevalence. This study was designed to determine the HPV genotypes and EBV involved in NPC tissue biopsies. A retrospective study design involving 72 formalin-fixed paraffin-embedded tissue (FFPET) samples of NPC from 2006 to 2012 were retrieved from the Department of Pathology, University of Ghana School of Biomedical and Allied Health Sciences. Sections were taken for histological analysis and for DNA lysate preparation. The DNA lysates were subjected to polymerase chain reaction (PCR) analysis to determine the presence of HPV genotypes and EBV. HPV specific primers were used to type for fourteen HPV genotypes (HPV-16, 18, 6/11, 31, 33, 35, 44, 42, 43, 45, 56, 52, 58, and 59). Out of the 72 NPC biopsies analyzed by PCR, EBV DNA was present in 18 (25%) cases and HPV DNA in 14 (19.23%). High risk HPV (HR-HPV) genotypes 18 and 31 were associated with the NPC. There were 3 (4.2%) cases of coinfection by both viruses. The EBV DNA present in the undifferentiated variant of the NPC and the histopathology of the NPC in Ghana is similar to the type described in endemic areas.

Figure 1

An electropherogram of Epstein-Barr virus PCR amplicons. The 229 bp fragment corresponds to the amplified EBV DNA. Lane M: 100 bp molecular size marker; NC: negative control (no DNA); PC: positive control; S2, S3, S5, and S6: EBV DNA positive samples; S1 and S4: EBV DNA negative samples.

Figure 2

An electropherogram of 2nd nested PCR products of human papillomavirus. The 322 bp and 263 bp fragments corresponding to the amplified HPV-18 and 31 DNA, respectively. Lane M: 100 bp molecular size marker; NC: negative control (no DNA); PC: positive control (HPV-18 plasmid DNA); S1: HPV-31 DNA positive sample; S3, S4, S5, S6, and S7: HPV-18 DNA positive samples.

Figure 3

Photomicrograph of the NPC histological subtypes. (A) Type 1 NPC: differentiated malignant squamous cells showing keratin peals (keratin formation). (B) Type 2 NPC: the tumour cells are spindle shaped with elongated dark nuclei and tapering cytoplasm. (C) Showing a type 3 NPC. The tumour cells have vesicular nuclei and prominent nucleoli; the cytoplasm has indistinct cytoplasmic borders. The small basophilic cells depict lymphocytosis (H&E stain 100x). Bar = 20 μm.