Epstein-Barr virus activation in Raji cells by extracts of preserved food from high risk areas for nasopharyngeal carcinoma

Epstein-Barr virus (EBV) activation of latent infection and traditional life styles, especially food habits, have been strongly associated with an increased risk of nasopharyngeal carcinoma (NPC) in humans. On the basis of anthropological studies in Tunisia, southern China and Greenland, extracts of representative preserved food items consumed frequently by the high-risk populations for NPC were assayed for the presence of EBV activators in Raji cells. A strong EBV activation activity was observed in aqueous extracts of some Cantonese salted dried fish from China, harissa (a spice mixture) and to a lesser extent qaddid (dry mutton preserved in olive oil) from Tunisia. These new data may support epidemiological evidence for the importance of Cantonese salted and dried fish and other food items in the etiology of NPC.

Wikstroemia indica promotes development of nasopharyngeal carcinoma in rats initiated by dinitrosopiperazine

Nasopharyngeal carcinoma was induced in an initiation/promotion model in rats by s.c. injection of dinitrosopiperazine in the nasopharyngeal cavity. This was followed by repeated 10-cal administration of an extract of roots of the Chinese medicinal herb WI (botanical family: Thymelaeaceae). Three groups of rats were used: group-1 received DNP followed by repeated WI; group-2 received DNP once; group-3 received WI repeatedly. At 180-205 days after DNP + WI administration 26% of the rats in that group exhibited NPC (two were carcinomas in situ and four were early infiltrating carcinomas). In the other two groups no carcinomas were found. In the group which received DNP followed by WI, other pathological changes, such as hyperplasia of nasopharyngeal epithelium, squamous metaplasia, and papillary hyperplasia, were also more frequent than that in the other two groups.

[Immunofluorescent localization of associated antigen of anti-human nasopharyngeal carcinoma cell monoclonal antibody]

The immunofluorescent localization of associated antigen of anti-human nasopharyngeal carcinoma (NPC) cell monoclonal antibody (McAb) was performed in different tissues (NPC, non-NPC tumor, chronic inflammation of nasopharyngeal mucosa, adult normal tissue and embryo tissue) with 5 control experiments. McAb (CN-1, Cs-C1) was produced by Department of Microbiology of our college and all the specimens were confirmed by pathology. The results revealed that Cs-C1 antigen was mainly found on the surface of NPC cells with a positive rate of 80.3%. Majority of the positive cells showed yellow-greenish linear fluorescence surrounding the cell membrane while some cells manifested granular fluorescence. In addition, Cs-C1 antigen was also found in a few embryo tissues, epithelial cells of the normal gastric mucosa and cells of the gastric cancer. It is suggested that Cs-C1 antigen be a kind of molecular structure, being gradually produced or increased in quantity during carcinogenesis, and belong to the tumor associated antigen. Cs-C1 antigen could be important in the study of carcinogenic mechanism of NPC cells and valuable to clinical immunodiagnosis.

[Promoting effect of the Chinese medicinal herb, wikstroemia chamaedaphne and tung oil extracts on carcinoma of the uterine cervix induced by HSV-2 or methylcholanthrene (MCA) in mice]

The promoting effect of the Chinese medicinal herb, Wikstroemia chamaedaphne and Tung oil extracts (WC and HHPA) on carcinoma of uterine cervix induced by HSV-2 or MCA in mice was studied. The results showed that WC and HHPA extracts were not carcinogenic themselves. After carcinogen HSV-2 and MCA treatment, WC and HHPA were added separately. The inducing rates by HSV-2 increased from 7.4% to 21.1% and 26.3%, those by MCA increased from 56.5% to 82.8% and 84.4%. There was a significant difference between the combined groups and groups with HSV-2 or MCA only. The experimental results suggest that these two kinds of extracts play a promoting effect on carcinogenesis. The relation between the carcinogenesis of uterine cervix or nasopharynx and WC or HHPA extracts is discussed.

Evaluation of monoclonal antibodies for the detection of exfoliative nasopharyngeal carcinoma cells

Exfoliative cells were aspirated from 15 patients suspected of having nasopharyngeal carcinoma (NPC) and showing the presence of lesions or other abnormalities in the nasopharynx. They were tested for binding with a 125I monoclonal antibody (MAb) (MA6) which is selectively reactive against human B lymphocytes and a variety of carcinomas. A positive result was obtained from 6/9 patients with, and from 0/5 patients without, histologically confirmed disease. One patient with eskimoma also gave a negative binding result. Cytology was specific but less sensitive, tumour cells being detected in 3 of the patients with confirmed disease. Immunocytology using MA6 was limited, like cytology, by poor recovery of the tumour cells and the results were in complete concordance with cytology. The other MAbs used were raised against carcinoembryonic antigen (CEA) and a carcinoma cell line (Ca2), respectively. The latter was not reactive against the NPC tumour cells while the CEA antibody was not sufficiently selective to be useful.

Detection of IgA antibody to EBV membrane antigen using Staphylococcus aureus preabsorbed sera is closely associated with nasopharyngeal carcinoma

The presence of IgA antibody to membrane antigen (MA) of Epstein-Barr virus (EBV) was tested in sera from 48 nasopharyngeal carcinoma (NPC) patients, 40 patients with tumors other than NPC and 46 normal individuals. The sera were preabsorbed with Staphylococcus aureus (SPA) (strain no. 1800) prior to their use in the indirect immunofluorescence test. One hundred percent of the NPC patients had the IgA/MA antibody with a GMT of 1:141. In patients with tumors other than NPC or normal individuals, IgA/MA antibodies were not detectable. The IgA/MA antibodies have been demonstrated in 6 NPC patients lacking detectable antibody levels in the indirect immunofluorescence test using nonabsorbed sera. Our data indicate that preabsorbtion of sera with SPA renders the diagnostic test significantly more sensitive for the detection of the nasopharyngeal carcinoma and can be used for trials on the prognosis of patients.

Detection of antibody to LAV/HTLV-III in sera from hemophiliacs in China

Using ELISA, Western blots and immunofluorescence techniques, we identified seropositivity for lymphadenopathy-associated virus/human lymphotropic virus-III (LAV/HTLV-III) in 4 of 18 hemophiliacs and 1 AIDS patient. The four seropositive patients had received factor VIII prepared by Armour Company. The hemophiliacs are all asymptomatic. Given this documentation of introduction of LAV/HTLV-III into China, a national surveillance program is underway.

Epstein-Barr virus seroepidemiology in China

Since 1978 more than 300,000 sera from normal individuals were screened serologically in NPC high risk areas and prospective studies were carried out. Many patients were diagnosed in early stage. For example, in Wuzhou city, 20,726 persons over 40 years of age were screened; 1,138 persons were found to have IgA VCA antibody. Among them 18 NPC cases were detected; an additional 21 NPC patients were found within 5 year follow-up studies. Altogether there were 39 NPC patients. As compared to the patients in outpatient clinics, the frequency of NPC in stage I increased from 1.7% to 38.5% and in early stage (I + II) increased from 32% to 92.3%. IgA VCA antibody can be detected 5 years before the diagnosis of NPC in early stage was made. The detection rate of NPC from IgA VCA antibody-positive persons is 38-374 times the incidence rate of NPC in the general population of the same age group. Follow-up studies on the change of IgA VCA antibody titer in antibody-positive and antibody-negative groups were also carried out for years. 10.9% of antibody-positive individuals became antibody negative and 5.4% seronegative persons converted to positive within 4 years. Eighty-eight per cent of NPC patients were detected in the group of no change of antibody titer or in the group of increasing antibody titer. No NPC patients were found in the original antibody negative group.

Detection of IgG and IgA antibodies to Epstein-Barr virus membrane antigen in sera from patients with nasopharyngeal carcinoma and from normal individuals

IgG and IgA antibodies to Epstein-Barr virus (EBV) membrane antigen (MA) were detected in sera from 96 NPC patients and normal individuals by the indirect immunofluorescence test. For MA/IgG antibody, 100% of NPC patients were positive with a GMT of 1:439.7 and 97.9% of normal individuals were positive with a GMT of 1:94.7. In contrast, for MA/IgA antibody, 58.3% of NPC patients were positive with a GMT of 1:7.3 and none of the normal individuals were positive. There was no difference in the detection of antibodies to EBV MA when other P3HR-1 or B95-8 cell lines, differing in their major membrane antigen, were used.

Prospective studies on nasopharyngeal carcinoma in Epstein-Barr virus IgA/VCA antibody-positive persons in Wuzhou City, China

A serological mass survey was carried out in Wuzhou City in 1980, 1,136 IgA/VCA-positive persons being followed up for 4 years. Altogether 35 NPC cases were detected, of which 15 (43%) were in stage I and 17 (48.5%) in stage II, early cases (I + II) thus amounting to 91.5%. The detection rate of early cases was 2.9 times higher than in our outpatient clinic. IgA/VCA antibody could be detected 16-41 months prior to clinical diagnosis of NPC. We conclude that, if IgA/VCA-positive individuals are examined routinely once a year, NPC can be detected in the early stages of evolution. The annual detection rate of NPC in IgA/VCA antibody-positive individuals was 31.7 times higher than that of the annual incidence of NPC in the general population in the same age group, while during the 4-year follow-up period the incidence was 7.5 times higher than in the general population for the same age group. These results further indicate that EB virus plays an important role in the development of NPC, and that serological screening and follow-up studies are valuable for the early detection of NPC.

Epstein-Barr virus activation by human semen principle: synergistic effect of culture fluids of bacteria isolated from patients with carcinoma of uterine cervix

Epstein-Barr virus early antigens (EBV EA) were induced in a Raji cell system in order to assay the activity of the EA inducer in human semen. In semen from 53 Chinese, 45.3% induced EBV EA in Raji cells. Such positive semen and EBV-inducing positive culture fluids of bacteria isolated from the uterine cervix of patients with cervical carcinoma had a synergistic effect on the induction of EBV EA. This synergistic effect as related to the cause of cervical carcinoma is discussed.

Epstein-Barr virus activation in Raji cells with ether extracts of soil from different areas in China

Epstein-Barr virus (EBV) inducers were found in soil samples collected from the ground under tung oil trees and other plant species of Euphorbiaceae family growing in southern provinces of China where incidence of an EBV-associated malignancy, nasopharyngeal carcinoma (NPC) is prevalent. In such NPC high risk areas, the positive rate of EBV inducers in soil samples was up to 59.5%. Since many tung oil trees are planted along the roads and rivers of the high risk area, the possible significance of EBV inducers in soil under the trees in the development of malignancy among inhabitants of the area is discussed.

Presence of EBV-DNA sequences in nasopharyngeal cells of individuals without IgA-VCA antibodies

Exfoliated nasopharyngeal (NP) cells from 62 normal Cantonese Chinese having IgA/VCA antibodies for more than a year and from 39 similar persons without IgA/VCA antibodies, were tested for the presence of EBV/DNA sequences by spot followed by blot hybridization tests, using the cloned internal repeat of B95-8 viral DNA as probe. Thirteen out of 62 specimens from IgA/VCA-positive (21%) and six out of 39 specimens (15.4%) from IgA/VCA-negative individuals were found to contain EBV/DNA sequences. Forty-six cases (20 IgA/VCA-positive and 26 IgA/VCA-negative) were followed a year later for EBV/DNA sequences and EBV serology. Half of the individuals having EBV/DNA sequences in their exfoliated NP cells in 1981 did not have detectable EBV sequences a year later, and to out of 15 negative individuals became EBV/DNA-positive. There was no obvious correlation between EBV/DNA detectability and EBV serology. (We conclude that the best marker for NPC risk remains the increasing IgA/VCA and/or EA antibody titers.

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.