Antibodies against Epstein–Barr virus gp78 antigen: a novel marker for serological diagnosis of nasopharyngeal carcinoma detected by xMAP technology

Abstract

Immunoglobulin (Ig) A and/or IgG reactivities to several Epstein-Barr virus (EBV) antigens have been used to facilitate diagnosis of nasopharyngeal carcinoma (NPC). However, antibodies against gp78, an EBV membrane glycoprotein, have not been examined to this day. In this study, we utilized Luminex multi-analyte profiling (xMAP) technology to analyse antibody responses to a synthetic peptide of gp78 in sera samples from 95 NPC patients and 91 healthy controls. Our results showed the sensitivity and specificity of IgA-gp78 for NPC diagnosis were 79 and 71 %, respectively, while those of IgG-gp78 were 74 and 73 %, respectively. The IgA and IgG responses to different EBV antigens were not identical within an individual and IgA-gp78 and IgG-gp78 could be complementary to antibodies against viral capsid antigen (VCA), the diffused early antigen (EA-D) and the nuclear antigen EBNA1 for NPC diagnosis. When the six EBV parameters for NPC prediction, i.e. IgA-gp78, IgG-gp78, IgA-VCA, IgA-EBNA1, IgA-EA-D and IgG-EA-D, are combined, the combined predictors were able to reach overall sensitivity and specificity of 91 and 95 %, respectively. Thus, simultaneous detection of these EBV serological markers could improve the predictive values of NPC using xMAP technology. INTRODUCTIONEpstein-Barr virus (EBV) is a ubiquitous gammaherpes virus composed of a protein core enclosed by DNA, an inner nucleocapsid with 162 capsomeres, a middle protein tegument, and an outer envelope carrying various membrane glycoproteins (Dolyniuk et al., 1976;Epstein et al., 1965;Khanna et al., 1995). EBV infects more than 90 % of the population worldwide and usually establishes a lifelong persistence in the host (Cohen, 2000). Most populations get primary infection in childhood and are asymptomatic, but Westerners whose primary infection is delayed until adolescence may develop infectious mononucleosis (Amon & Farrell, 2005). More strikingly, the virus is associated with a spectrum of cancers presenting endemic features, such as Burkitt's lymphoma in Africa and nasopharyngeal carcinoma (NPC) in Southern China and South-East Asia (Pattle & Farrell, 2006;Raab-Traub et al., 1987).EBV is closely correlated with NPC, which could be reflected by consistent expression of EBV gene products in NPC tumour cells and general elevation of serum antibody levels against EBV antigens in NPC patients (Busson et al., 2004;Gastpar et al., 1981;Henle & Henle, 1976;Old et al., 1966;Raab-Traub, 2002). In comparison with healthy EBV carriers, NPC patients typically show strong IgG and especially IgA reactivities to lytic antigens (Fachiroh et al., 2004;Henle & Henle, 1976), so an EBV serological assay could facilitate diagnosis and prognosis of NPC. IgA antibody titres against the EBV viral capsid antigen (VCA) and the diffused early antigens (EA-D) are regularly tested in many clinical centres (Deng et al., 1995; Hadar et al., 1986;Henle & Henle, 1976;Ho et al., 1998 et al., 2004). However, few of them have been shown as valuable markers for NPC diagnosis. gp350/220 is t...

Epstein–Barr virus facilitates the malignant potential of immortalized epithelial cells: from latent genome to viral production and maintenance

“…Serological studies on Burkitts's lymphoma and NPC have shown that elevated antibody titers against EBV lytic antigens may correlate with advanced cancer stages, poor prognoses, or poor tumor therapy. 6,9,41,42 Some clues have indirectly indicated that EBV reactivation into lytic cycle may occur during tumor development. 43,44 In our study, matured and budding virions were observed, directly confirming that EBV reactivation occurred spontaneously from latent genome to viral production in some cells at the site of tumor development.…”

Rapid detection of antibodies in sera using multiplexed self-assembling bead arrays

“…The recent development of spectrally-distinguishable fluorescent beads (Luminex) (Kellar and Iannone, 2002) has resulted in the widespread use of antigen-coupled beads for monitoring antibodies in sera by flow cytometry. These bead arrays have been adapted for serologic screening of antigens and has been described for up to ten antigens for HIV (Opalka et al, 2004), HPV (Opalka et al, 2003; Dias et al, 2005), Epstein-Barr virus (Klutts et al, 2004; Binnicker et al, 2008; Gu et al, 2008), B. anthracis (Biagini et al, 2004; Biagini et al, 2005), Influenza (Drummond et al, 2008) and M. tuberculosis (Khan et al, 2008). When using purified antigens covalently linked on the beads, multiplexed serologic screening is both highly sensitive and efficient, but requires bacterial protein production and protein purification.…”

Biomarkers for Cancers of the Head and Neck

“…Moreover, increasing availability of these assays with distinct antigenic specifi city makes it possible to use the assays in combination in an approach to effect diagnosis of NPC based on EBV antibody spectrum rather than the level of individual antibodies. Reports by Gu et al showed that IgA and IgG antibodies against gp78, a membrane protein, were statistically higher in NPC populations than in healthy controls (49). They suggested the use of Luminex multi-analyte profi ling (xMAP) technology to detect multiple parameters in NPC, such as antibodies against gp78, VCA, EA-D and EBNA1 simultaneously (see Table 1).…”