Interaction of Influenza Virus with Blood Platelets

The interaction of human blood platelets with influenza virus (PR-8) wasstudied in vitro and in vivo.

It was found that "live" influenza virus was rapidly adsorbed onto humanblood platelets at 4 C. and completely eluted at 37 C. "Dead" virus wasadsorbed at 4 C. but not eluted at 37 C. unless the platelets were treated withRDE (receptor destroying enzyme). Adorption of virus also occurred at temperatures above 4 C. (from 20 to 37 C.). However, while adsorption wasmaintained throughout incubation at 4 C., slow elution occurred after 30 to 90minutes incubation at 26 to 37 C. Storage of the platelets for lengthy intervalsat 4 C. or coating of the platelets with macromolecules did not interfere withvirus adsorption. After one cycle of adsorption-elution, blood platelets couldnot adsorb virus again. Treatment with RDE greatly reduced virus adsorption.During the process of virus adsorption, prominent platelet clumping occurred.During elution, clumping remained unchanged, and gross alterations in morphology of the platelets were observed. In the process of virus adsorption-elution, large numbers of platelets were lysed.

Comparative experiments were performed simultaneously with human redblood cells (RBC) and identical results were obtained as with blood platelets.However, the extent of adsorption of live virus was equal for platelets andRBC only when the relationship between platelet number and RBC number inthe preparations used was 6:1. This suggested a direct proportion between thesurface area of both platelet and RBC and the number of available virusreceptors.

Virus suspensions infused into rabbits produced a sharp and sustained dropof the platelet count. Survival of radioactively labeled platelets treated withvirus prior to infusion was markedly shortened with live virus and was onlyslightly reduced with dead virus.

It is suggested from these experiments that blood platelets, as other bloodcells, may serve as carriers of viruses in the circulation and that in this processthe platelets are damaged and partially destroyed.

Submitted on June 30, 1965 Accepted on January 31, 1966