Quantitative investigation of the direct interaction between Hemagglutinin and fusion proteins of Peste des petits ruminant virus using surface Plasmon resonance.

BACKGROUND: The specific and dynamic interaction between the hemagglutinin (H) and fusion (F) proteins of morbilliviruses is a prerequisite for the conformational rearrangements and membrane fusion during infection process. The two heptad repeat regions (HRA and HRB) of F protein are both important for the triggering of F protein. METHODS: In this study, the direct interactions of Peste des petits ruminants virus (PPRV) H with F, HRA and HRB were quantitatively evaluated using biosensor surface plasmon resonance (SPR). RESULTS: The binding affinities of immobilized pCMV-HA-H (HA-H) interacted with proteins pCMV-HA-F (HA-F) and pCMV-HA-HRB (HA-HRB) (KD = 1.91 × 10- 8 M and 2.60 × 10- 7 M, respectively) reacted an order of magnitude more strongly than that of pCMV-HA-HRA (HA-HRA) and pCMV-HA-Tp IGFR-LD (HA) (KD = 1.08 × 10- 4 M and 1.43 × 10- 4 M, respectively). CONCLUSIONS: The differences of the binding affinities suggested that HRB is involved in functionally important intermolecular interaction in the fusion process.