Distinctive RNA transcriptase, polyadenylic acid polymerase, and polyuridylic acid polymerase activities associated with Pichinde virus

Abstract

Three RNA polymerase activities were associated with purified Pichinde virus, a member of the Arenaviridae. A heat-labile polymerase activity which required all 4 ribonucleoside triphosphates for optimal activity cosedimented on sucrose gradient centrifugation with the viral ribonucleoprotein complex from detergent-disrupted virus preparations. This enzyme synthesized heteropolymers which represented about 23% of the genome RNA as determined by nucleic acid hybridization. Two relatively heat-stable polymerase activities which differed in their cation requirement and substrate specificity were recovered with the virus-associated ribosomes. These polymerase activities synthesized homopolymers of limited chain length: in the presence of 10 mM Mg2+, poly(U) was made; in the presence of 1 mM Mn2+, poly(A) was made. The addition of complementary RNA synthesized with the viral transcriptase in vitro to the reaction mixture containing the poly(A) polymerase activity resulted in the terminal addition of poly(A) to the complementary RNA. The possible function of the ribosome-associated polymerase activities in the replication of the virus is discussed.