Interaction between Epstein-Barr virus and a T cell line (HSB-2) via a receptor phenotypically distinct from...

Epstein-Barr virus (EBV), the causative agent of mononucleosis and several human cancers, infects cells via complement receptor type 2 (CR2, CD21) which also serves as the receptor for the third complement component, C3. Expression of this receptor is restricted to B lymphocytes, immature thymocytes, and certain epithelial cells. In the present investigation; we describe the presence of a seemingly novel EBV receptor which is phenotypically distinct from CR2. Among various leukemic T cells studied, one, HSB-2, demonstrates no reactivity to several anti-CR2 antibodies, yet it reacts strongly with EBV as detected by incubation with biotin-conjugated virus and streptavidin-phycoerythrin. The virus binding is specific as demonstrated by blocking with anti-EBV antibodies and with non-conjugated virus. Aggregated C3 also binds HSB-2 and is capable of partially inhibiting EBV binding. The absence of CR2 on HSB-2 is further supported by the lack of expression of specific mRNA, assessed by Northern blotting analysis and polymerase chain reaction. Viral internalization and infection is demonstrated with electron microscopy, with detection of EBV-DNA by Southern blotting, and with detection of EBNA-1 transcripts by the polymerase chain reaction. Even though HSB-2 does not express CR2, it nevertheless displays transcripts which have some homology to a CR2 cDNA probe under low stringency hybridization conditions. This probe encompasses approximately the N-terminal half of CR2 which includes the EBV-binding epitope(s). The HSB-2 message is 5.2 kb, a size distinct from the 4.7-kb message of B cell CR2s. In contrast, the 5.2-kb message in not seen, under similar hybridization conditions, with a probe comprising the C-terminal half of CR2. Collectively, the data indicate that a receptor molecule having distinct phenotypic characteristics from the known CR2 protein on B cells is utilized by EBV to target human T lymphocytes.