Counts of Influenza Virus Particles

Abstract

SUMMARY: Particle counts of influenza virus preparations were made by two independent techniques; there was good agreement in the counts found by the two methods. Counts made on four strains of influenza virus and one strain of ‘incomplete’ virus showed that at the agglutination end-point there was about one virus particle per red cell. Parallel infectivity measurements of these strains made under optimal conditions showed that about ten virus particles corresponded to one ID 50.