Antibodies to Epstein-Barr virus in patients with nasopharyngeal carcinoma in Northern Ireland

Serological diagnosis of Epstein-Barr virus infection: Problems and solutions

Serological tests for antibodies specific for Epstein-Barr virus (EBV) antigens are frequently used to define infection status and for the differential diagnosis of other pathogens responsible for mononucleosis syndrome. Using only three parameters [viral capsid antigen (VCA) IgG, VCA IgM and EBV nuclear antigen (EBNA)-1 IgG],it is normally possible to distinguish acute from past infection: the presence of VCA IgM and VCA IgG without EBNA-1 IgG indicates acute infection, whereas the presence of VCA IgG and EBNA-1 IgG without VCA IgM is typical of past infection. However, serological findings may sometimes be difficult to interpret as VCA IgG can be present without VCA IgM or EBNA-1 IgG in cases of acute or past infection, or all the three parameters may be detected simultaneously in the case of recent infection or during the course of reactivation. A profile of isolated EBNA-1 IgG may also create some doubts. In order to interpret these patterns correctly, it is necessary to determine IgG avidity, identify anti-EBV IgG and IgM antibodies by immunoblotting, and look for heterophile antibodies, anti-EA (D) antibodies or viral genome using molecular biology methods. These tests make it possible to define the status of the infection and solve any problems that may arise in routine laboratory practice.

Search for Anti-EA(D) Antibodies in Subjects with an "Isolated VCA IgG" Pattern

The presence of an “isolated viral capsid antigen (VCA) IgG” pattern in serum is not easy to interpret without the aid of further tests, such as specific immunoblotting or a virus genome search, that often give rise to organisational and economic problems. However, one alternative is to use an enzyme-linked immunosorbent assay (ELISA) to detect anti-early antigen (EA) antibodies, which can be found in about 85% of subjects with acute Epstein-Barr virus (EBV) infections. The purpose of this work was to search for anti-EA(D) antibodies in 130 samples with an isolated VCA IgG pattern at ELISA screening and classified as being indicative of past (102 cases) or acute (28 cases) infection on the basis of the immunoblotting results. Thirty-seven samples (28.5%) were positive for anti-EA(D), of which 25 (89.3%) had been classified by immunoblotting as indicating acute and 12 (11.8%) past EBV infection. This difference was statistically significant (P < .01). The results of our search for anti-EA(D) antibodies correctly identified nearly 90% of acute (presence) or past EBV infections (absence). When other tests are not available, the search for anti-EA antibodies may therefore be helpful in diagnosing patients with an isolated VCA IgG pattern at screening tests.

Compact Epstein-Barr virus diagnosis based on a defined antigen mix and specific IgA

An ELISA was evaluated to measure EBV-specific IgM, IgG and IgA using a test plate coated with a controlled mix of EA, VCA and EBNA. Using the IgM version, the multi-reactive surface reduced false-negative findings in cases of infectious mononucleosis (sensitivity 98%), but was confronted with polyclonal IgM responses (specificity 85% to 95% depending on the population). For the IgG version, a national research standard was involved, and in combination with the IgA estimation, a new diagnostic strategy became possible for chronic EBV infections and reactivations. Patients screened by enhanced IgG (> 650 U/ml) were confirmed by an elevated IgA signal (> 0.6 A), with an efficacy of 95%. A raised virus-specific IgA response was not observed in cases of infectious mononucleosis, but was seen for healthy HIV-positive persons. Superior to the traditional antibody puzzle for EBV diagnosis, it will now become possible, using this compact diagnostic concept, to reduce laboratory expenses without loss of reliable results.

Prognostic value of Epstein-Barr virus serology in patients with nasopharyngeal carcinoma

We report the results of a study which examined the prognostic value of Epstein-Barr virus (EBV) serology in patients with nasopharyngeal carcinoma (NPC). Antibody titres to EBV were estimated by indirect immunofluorescence and correlated with the stage of disease. Neither persistent high titres nor falling titres after treatment were found to be reliable indicators of relapse or survival, respectively, in individual patients. By contrast, four-fold rises in titre, particularly of antibodies to the early antigens of the virus were highly significant predictors of relapse. These increases could be seen well in advance of clinical detection of recurrence of the tumour at the primary or metastatic sites.