Abstract:
Jaagsiekte (ovine pulmonary adenomatosis) was transmitted to new-born lambs by inoculation
of the microsomal fraction of a cytoplasmic extract of cultured tumour cells or tumour tissue. Various
treatments of the biologically active fraction were carried out to differentiate between various classes
of possible aetiological agents. The results obtained suggested the involvement of a membraneassociated
RNA containing virus. Reverse transcriptase activity dependent on Mg++ was subsequently
demonstrated in these extracts and in lung exudate, and was shown to be associated with particles
banding at a density of 1 , 175 in sucrose gradients. These characteristics, as well as the appearance of
the particles in the electron microscope, are similar to those reported for Type B and Type D retroviruses.
Serial transmissions of jaagsiekte over a number of years, using cytoplasmic extracts and
purified virus, strongly suggest that this virus is the aetiologic agent of jaagsiekte.
