PLAQUE FORMATION AND ISOLATION OF PURE LINES WITH POLIOMYELITIS VIRUSES

TLDR

Plaques were produced by infecting monkey kidney and testis monolayer cultures with three poliomyelitis virus types, and high‑titer stocks (up to 7×10^8 PFU/mL) were obtained. Plaque counts increased proportionally with viral concentration, each plaque arising from a single virus particle, and were inhibited by type‑specific antiserum; isolation of single‑plaque populations yielded pure virus lines that retained the parent strain’s morphology, serology, and pathogenicity.

Abstract

Plaques have been produced with the three types of poliomyelitis viruses on monolayer tissue cultures of monkey kidney and monkey testis. The number of plaques was proportional to the concentration of the virus. Each plaque originates, therefore, from a single virus particle, defined as the virus unit that is unseparable by dilution. The plaques are due to the specific action of the virus since they are suppressed by type-specific antiserum. Pure virus lines were established by isolating the virus population produced in single plaques. These derived virus lines had the same morphological, serological, and pathogenic properties as the parent strain. High titer virus stocks, with titers up to 7 x 10(8) plaque-forming particles per ml., were obtained.