Background and objective: Nasopharyngeal carcinoma (NPC), with a remarkable geographic distribution, is consistently associated with Epstein-Barr virus (EBV) infection, and almost all NPC patients have sustained high levels of serum antibodies against EBV. This study was to compare the levels of six anti-EBV antibodies in healthy natives of Zhongshan (a high-incidence area of NPC) with those in provisional migrants from foreign provinces (low-incidence areas of NPC), and to illustrate the relationship between EBV infection and the geographic distribution of NPC.
Methods: The serum levels of EBNA1-IgA, EBNA1-IgG, VCA-p18-IgA, VCA-p18-IgG, Zta-IgA and Zta-IgG in 303 healthy Zhongshan natives and 92 provisional migrants were tested using ELISA, and presented by values of adjusted relative absorbance (ArA). The serum levels and positive rates of the six antibodies were compared between the two groups.
Results: The mean ArA values of both Zta-IgA and VCA-p18-IgA were significantly higher in Zhongshan natives than in provisional migrants (0.84+/-0.03 vs. 0.42+/-0.04, P <0.05; 0.96+/-0.05 vs. 0.40+/-0.05, P<0.05). In addition, the positive rates of Zta-IgA and VCA-p18-IgA in subjects aged of 30-49, or of 50 and above were significantly higher in Zhongshan natives than in provisional migrants (29.27% vs. 3.03% and 48.28% vs. 6.67% for Zta-IgA, P<0.05; 28.46% vs. 9.09% and 43.10% vs. 13.33% for VCA-p18-igA, P<0.05).
Conclusion: Zhongshan natives are likely to have an elevation of serum IgA antibodies against EBV lytic antigens (Zta and VCA-p18), which represents reactivation of EBV latency infection and implies that Zhongshan natives may have higher risk to develop NPC than provisional migrants.