A Field Experiment to Assess the Role of Parainfluenza Type 3 Virus in Pneumonia in a Flock of Sheep in Victoria

Abstract

A flock of 33 lambs born to ewes with neutralizing antibody to parainfluenza type 3 (PI3) virus was run with a flock of approximately 150 other lambs and their mothers. When bled shortly after birth, lOO% of the 33 lambs had maternal anti-body to PI3 virus. Four months later, the proportion h!lod fallen to 22%, about which time a natural infection with PI3 virus occurred in the flock as judged by subsequent appearance in the sera of PI3 serum neutralizing antibody.