Follow-up studies on Epstein-Barr virus IgA/VCA antibody-positive persons in Zangwu County, China

Serological mass surveys were carried out in Zangwu County, China, using an immunoenzymatic test. 3,533 persons were found to have Epstein-Barr virus (EBV) IgA/VCA antibody among 148,029 persons age 30 years and older who were tested during 1978-1980. Among the IgA/VCA antibody-positive persons, 55 nasopharyngeal carcinoma (NPC) cases were detected. Follow-up studies were carried out yearly on the IgA/VCA antibody-positive persons for 1-3 years, and 32 additional NPC patients were diagnosed. IgA/VCA antibody was detected 8-30 months (average, 13 months) prior to the clinical diagnosis of stage I NPC. There was no marked difference in geometric mean titers of IgA/VCA antibody between the period before onset of NPC and after diagnosis at stage I, but antibody titers were higher during stages II-IV. The NPC detection rates for all persons tested serologically and for IgA/VCA antibody-positive persons, respectively, was 2- and 82-fold the annual incidence of NPC in the general population of the same age group. These data further indicate that serological testing is valuable for the diagnosis of NPC, especially in its early stages, and that EBV may play an important role in the development of NPC.

Epstein-Barr virus early antigen induction in Raji cells by Chinese medicinal herbs

Ether extracts of 495 Chinese medicinal herbs from 106 families were studied for Epstein-Barr virus (EBV) early antigen (EA) induction in the Raji cell system. 15 herbs from 10 families were found to have inducing activity. Water extracts of the same herbs also had inducing activity, but it was not as strong. The significance of these herbs in the activation of EBV in vivo and their relation to the development of nasopharyngeal carcinoma are discussed. No EA-inducing activity was found in 73 samples of 14 different foods tested.

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.