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Kinetics of Multiplication, Inactivation, and Particle-Breakdown of Cowpea Chlorotic Mottle Virus in Cowpea. W. O. Dawson, Department of Plant Pathology and Plant Genetics, University of Georgia, Athens 30602, Present address of senior author: Department of Plant Pathology, University of California, Riverside 92502; C. W. Kuhn, Department of Plant Pathology and Plant Genetics, University of Georgia, Athens 30602. Phytopathology 64:951-957. Accepted for publication 25 January 1974. DOI: 10.1094/Phyto-64-951.

In cowpea leaves grown at constant temp of 16, 21, 27, and 32 C, cowpea chlorotic mottle virus (CCMV) nucleoprotein and infectivity increased earlier and specific infectivity decreased earlier at each of the higher temp. After an initial lag period, the multiplication rates increased exponentially to a peak. As a specific maximum concn of virus was attained, the multiplication rate rapidly declined to a low level which continued for the duration of the infection. At 27 and 32 C, little CCMV synthesis occurred after the first 6-8 days of the infection. Substantial quantities of particle breakdown occurred at 21, 27, and 32 C and little or none at 16 C. More particle breakdown occurred than was demonstrated by the virus nucleoprotein concn curves because multiplication continued as the nucleoprotein concn decreased. Inactivation of CCMV was affected more by temp than were either multiplication or particle breakdown. The in vivo inactivation followed first-order kinetics with the rate constant being temp-dependent. The half-lives of in vivo infectivity of CCMV were approximately 2.5 days at 32 C and 4 days at 27 C. Little inactivation occurred at 16 C. Although inactivation was rapid at temp above 21 C, all infectivity was never lost, even at 38 C.

Additional keywords: radioisotope studies, specific infectivity.