Serological mass survey for early detection of nasopharyngeal carcinoma in Wuzhou City, China

A serological mass survey was carried out in Wuzhou City of the Guangxi Autonomous Region, China. Sera were collected from 12,932 persons between the ages of 40 and 59. The positive rate of VCA/IgA antibody-positive person was 5.3%, but no EA/IgA antibody was found in sera from VCA/Iga-negative persons. Thirteen and nine nasopharyngeal carcinoma (NPC) patients were detected from the VCA/Iga and EA/IgA antibody-positive persons, respectively. With the present combination method the detection rate of NPC for 12,932 persons was 100.5/100,000 and for 680 VCA/IgA antibody-positive persons it was 1,900/100,000. Thus, the rate was twice and 37 times higher, respectively, than the annual incidence rate of NPC in persons of the same age group from 1975-1978 in Wuzhou City. Of 13 NPC patients, 9 were in stage I (70%) and 4 in stage II (30%). Therefore, it is possible to reduce the mortality rate of NPC in Wuzhou City by radiotherapy of NPC patients in the early stage of the disease. The present results further suggest that EB virus is closely associated with NPC.

Detection of Epstein-Barr viral DNA internal repeats in the nasopharyngeal mucosa of Chinese with IgA/EBV-specific antibodies

Fifty-six South Chinese individuals exhibiting IgA antibodies to EBV for 18 months and presenting nasopharyngeal abnormalities were biopsied. Four nasopharyngeal carcinomas, two at a very early stage, were detected. In 14 further individuals, without clinical or histopathological evidence of tumor, EBV/DNA internal repeats and/or EBNA were detected in the biopsied mucosae. The presence of IgA/EBV antibodies and/or EBV markers in the nasopharyngeal mucosa may characterize pre-cancerous conditions.

Enhancement of spontaneous VCA and EA induction in B95-8 cells and EA induction in Raji cells treated with human leukocyte interferon

The purpose of this study was to determine the antiviral effect of human leukocyte interferon on Epstein-Barr virus (EBV) viral capsid antigen (VCA) and early antigen (EA) induction in B95-8 and Raji cells. Interferon made at the Institute of Virology, Beijing, and that provided by Dr. Cantell gave unexpected results. Both interferon preparations markedly enhanced spontaneous VCA and EA induction in B95-8 cells and EA induction in Raji cells simultaneously treated with croton oil and n-butyrate. Interferon treatment alone had no effect on EA induction in Raji cells. Thus, the effect of interferon on EA and VCA induction was related to the type of EBV infection, i.e., productive or latent. The enhancing activity of interferon could only be partially inhibited by retinoid 7901. It is suggested that the mechanism for enhancement of EA induction by interferon is different from that of EA induction in Raji cells by croton oil and n-butyrate.

Inhibitory effect of retinoids on Epstein-Barr virus induction in Raji cells

Induction of Epstein-Barr virus (EBV) early antigen after treatment with various combinations of croton oil and n-butyrate was markedly inhibited by retinoids 7901, 7902, Ro 10-9359 and Ro 11-1430. Possible administration of retinoids to virus capsid antigen IgA antibody-positive individuals in high-risk areas for nasopharyngeal carcinoma to prevent EBV activation and development of this cancer is discussed.