To systematically compare EBV and KSHV antibody responses, we utilized proteomic arrays displaying 174 virus proteins plus controls. The printing quality and the quantity of the immobilized proteins on the chip were monitored using anti-GST antibody followed by Cy3-labeled secondary antibody ( Figure 1A ). Preliminary analyses with arrays containing the 82 EBV and 92 KSHV ORFs revealed that plasma diluted up to 1:10 000 gave a signal on the arrays that was readily detected with Cy3-tagged antihuman IgG. A positive signal was set as one that was 5 SD or more above background. A section of the array illustrating positive and control signals is shown in Figure 1B . ORF38 is a tegument protein that has not been widely examined as an antigen. ORF73 encodes the latency LANA protein that is a gold standard for KSHV serology studies. The central region of LANA contains repeated sequences that limit effective expression of the protein in yeast. The N-terminus and C-terminus of LANA were therefore expressed separately for presentation on the array. The LANA C-terminus was recognized more frequently than the N-terminus (14 vs 4 positive plasma). This is consistent with a peptide mapping study that found more sera reacting to peptides mapping to the LANA C-terminus than to the N-terminus [28] . The median number of KSHV antigens recognized by the LANA-positive HIV 1 /KS plasma at 1:10 000 serum dilution was 6. Analysis of the EBV proteins recognized in the same assay by the same plasma samples revealed a different picture. EBV is a ubiquitous virus, and EBV proteins on the array were recognized using plasma from healthy donors, HIV 2 lymphoma patients, and HIV 1 /KS patients ( Figure 2B ). The median number of EBV proteins recognized at 1:100 serum dilution was 17, 18, and 27 for plasma from healthy donors, lymphoma patients, and HIV 1 /KS patients, respectively. Ninety-one percent of plasma specimens tested (32/35) reacted with the carboxy terminus of EBNA1 and 97% (34/35) reacted with the combination of EBNA3B and EBNA3C at 1:100 or 1:10 000 dilution. The single EBNA3-negative plasma specimen was from a lymphoma patient whose plasma did not recognize any EBV antigens. The difference between the normal and HIV 2 lymphoma population and the HIV 1 /KS population lay not in the individual antigens recognized, but rather in the heightened antigenic response to a range of EBV proteins. This is illustrated by the increased median number of antigens detected at 1:10 000 plasma dilution seen with HIV 1 /KS samples (15) vs the median number with plasma from healthy donors and lymphoma patients (7 and 5, respectively). Antigens with a statistically significant difference in appearance between healthy donors and HIV 1 /KS patients at a 1:10 000 dilution are shown in Figure 3 , which also includes the data for HIV-negative lymphoma patients for comparative purposes. The BFRF3 (p18) capsid antigen has been previously advocated as a serological marker for nasopharyngeal carcinoma diagnosis [29] .