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Published on: March 2, 2014
Eph Receptor Tyrosine Kinases Are Functional Entry Receptors for Murine Gammaherpesvirus 68
Anna Katharina Großkopf1, Victor Tobiasson2, Laurie T Krug1
1HIV and AIDS Malignancy Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, United States of America.
Abstract:
Interactions between viral glycoproteins and cellular receptors determine virus tropism and represent promising targets for vaccines. Eph receptor tyrosine kinases are conserved receptors for the human oncogenic gammaherpesviruses, Kaposi sarcoma herpesvirus (KSHV) and Epstein-Barr virus (EBV), and mediate entry into target cells by interaction with the viral gH/gL glycoprotein complex. To evaluate the use of murine gammaherpesvirus 68 (MHV68), a natural pathogen of rodents, as an in vivo model system for early events in gammaherpesvirus infection, we characterized the interaction of the MHV68 gH/gL complex with Eph receptors. We demonstrate a direct interaction of MHV68 gH/gL with EphA4 and EphB3, that is conserved between human and murine receptors. Pre-incubation of MHV68 inocula with soluble decoy receptors decreased infection of permissive fibroblasts. Ectopic expression of EphA4 and EphB3 enabled MHV68 to infect otherwise non-permissive human B cells, demonstrating EphA4 and EphB3 receptor function. Targeted mutations informed by protein structure predictions demonstrate that the MHV68 gH/gL-Eph interaction is determined by domain I (D-I) and follows structural motifs previously described in the KSHV gH/gL-EphA2 complex. The importance of gH D-I is further highlighted by the analysis of gH-targeting neutralizing antibodies. Antibody adsorption via the full gH ectodomain or gH D-I led to comparable reductions in neutralization capacity of serum from WT infected mice, indicating the Eph-binding domain is a major target for gH/gL-directed neutralizing antibodies. Our study characterizes Eph receptors as novel interaction partners and entry receptors for MHV68. Conservation of entry mechanisms provides the basis for future in vivo analyses of the contribution of Eph receptors to cell-type dependent MHV68 infection, as well as targeted strategies to prevent transmission and diseases associated with chronic infection.
Insights
Murine gammaherpesvirus 68 (MHV68) uses Eph receptors, like EphA4 and EphB3, for cell entry. This interaction is conserved across species and targets neutralizing antibodies, supporting MHV68 as an in vivo infection model.
Area of Science:
- Virology
- Immunology
- Cell Biology
Background:
- Viral glycoproteins and cellular receptors dictate virus tropism and are vaccine targets.
- Eph receptor tyrosine kinases are known receptors for human gammaherpesviruses (KSHV, EBV), mediating entry via the viral gH/gL complex.
- Murine gammaherpesvirus 68 (MHV68) is a rodent pathogen used to model early gammaherpesvirus infection events.
Purpose of the Study:
- To characterize the interaction between the MHV68 gH/gL complex and Eph receptors.
- To evaluate MHV68 as an in vivo model for gammaherpesvirus entry mechanisms.
- To identify potential targets for therapeutic intervention against MHV68 infection.
Main Methods:
- Direct interaction assays between MHV68 gH/gL and Eph receptors (EphA4, EphB3).
- Infection studies using permissive and non-permissive cells, including those with ectopic Eph receptor expression.
- Analysis of neutralizing antibodies targeting the MHV68 gH ectodomain, particularly domain I (D-I).
- Protein structure predictions to guide targeted mutagenesis.
Main Results:
- MHV68 gH/gL directly interacts with EphA4 and EphB3 receptors, conserved between human and murine Eph receptors.
- Soluble decoy Eph receptors reduced MHV68 infection of fibroblasts.
- Ectopic expression of EphA4 and EphB3 enabled MHV68 entry into non-permissive human B cells.
- The MHV68 gH/gL-Eph interaction is mediated by domain I (D-I) of gH, consistent with KSHV.
- Neutralizing antibodies targeting gH D-I significantly reduced MHV68 neutralization capacity.
Conclusions:
- Eph receptors (EphA4, EphB3) are identified as novel interaction partners and entry receptors for MHV68.
- The conserved entry mechanism involving Eph receptors provides a basis for in vivo studies of MHV68 infection.
- The Eph-binding domain of gH is a key target for neutralizing antibodies, offering potential for vaccine development.
