Prevalence and viral load of oncogenic human papillomavirus (HPV) in pterygia in multi‐ethnic patients in the Malay Peninsula

Abstract

ABSTRACT.Purpose: The aim of the study was to determine the prevalence of human papillomavirus (HPV) in primary and recurrent pterygia samples collected from different ethnic groups in the equatorial Malay Peninsula. Methods: DNA was extracted from 45 specimens of freshly obtained primary and recurrent pterygia from patients and from 11 normal conjunctival swabs from volunteers with no ocular surface lesion as control. The presence of HPV DNA was detected by nested PCR. PCR-positive samples were subjected to DNA sequencing to determine the HPV genotypes. Real-time PCR with HPV16 and HPV18 typespecific TaqMan probes was employed to determine the viral DNA copy number. Results: Of 45 pterygia samples with acceptable DNA quality, 29 (64.4%) were positive for HPV DNA, whereas all the normal conjunctiva swabs were HPV negative. Type 18 was the most prevalent (41.4% of positive samples) genotype followed by type 16 (27.6%). There was one case each of the less common HPV58 and HPV59. Seven of the samples harboured mixed infections of both HPV16 and HPV18. All the four known recurrent pterygia samples were HPV-positive, whereas the sole early-stage pterygium sample in the study was HPV-negative. There was no significant association between HPV-positive status with gender or age. A high proportion of patients from the Indian ethnic group (five of six) were HPV-positive, whereas the Malay patients were found to have higher HPV positivity than the Chinese. The viral load of HPV18 samples ranged between 2 3 10 2 and 3 3 10 4 copies per lg, whereas the viral load of HPV16 specimen was 4 3 10 1 to 10 2 copies per lg. Conclusion: This report describes for the first time the quantitative measurement of HPV viral DNA for pterygium samples. The high prevalence of oncogenic HPVs in our samples suggests a possible role for HPV in the pathogenesis of pterygia. Moreover, the relatively low HPV viral load is concordant with the premalignant nature of this ocular condition.

Molecular Basis of Pterygium Development

“…According to these reviews, the lowest prevalence of HPV in pterygium samples has been identified in Turkish, Japanese, and Ecuadoran patients (0%, 4.8%, and 21%, respectively), [82][83][84] while the highest prevalence has been reported for Italian, Brazilian, and English patients (100%, 58.3%, and 50%, respectively). [84][85][86] Recent research also reports contrasting results: Chong et al 87 found a prevalence of 64.4% in patients from the Malay Peninsula, whereas Woods 88 reported 0% in patients from Australia. The disparity in these prevalence rates has been attributed to ethnic and geographical factors, as well as to the laboratory techniques and study designs used.…”

Ocular Human Papillomavirus Infections

“…17 Epidemiologic studies suggest that exposure to ultraviolet B light (UVB) is an important risk factor. 1,14,[18][19][20][21][22][23] In particular, pterygia are more common in individuals who live near the equator and in those who work outdoors. UVB has been postulated to interact with a variety of cofactors, including HPV and the p53 tumor suppressor gene, to genetically alter nasal limbal epithelial stem cells, leading to the development or recurrence of pterygia.…”

“…UVB has been postulated to interact with a variety of cofactors, including HPV and the p53 tumor suppressor gene, to genetically alter nasal limbal epithelial stem cells, leading to the development or recurrence of pterygia. 1,14,18,19,24 This ''two-hit'' hypothesis is supported by the detection of the high-risk HPV strains 16 and 18, encoding E6 and E7 proteins, which interfere with p53 function, in pterygium. 14,22,24,25 However, the rates of detection of HPV in pterygia vary considerably (range, 0%-100%) in published reports.…”

“…14,22,24,25 However, the rates of detection of HPV in pterygia vary considerably (range, 0%-100%) in published reports. 1,14,[17][18][19]22,[26][27][28][29][30][31][32][33] These discrepancies have been explained by potential ethnic or geographic differences in rates of HPV infection and by varying laboratory techniques used to detect HPV. Alternatively, these results may reflect the heterogeneous nature of pterygium pathogenesis and the possibility that HPV plays a role in the development of only a subset of pterygia.…”

Asociación del virus del papiloma humano con enfermedades oculares del segmento anterior y los párpados

“…El potencial oncogénico del VPH ha sido ampliamente estudiado. El ADN viral se encuentra en tumores benignos y malignos, papilomas especialmente de las mucosas: VPH 16 y VPH 18 (11)(12)(13)(14).…”