The effect of herpes simplex virus type 2 (HSV-2) infection on the synthesis of DNA in human embryonic fibroblast cells was determined at temperatures permissive (37 C) and nonpermissive (42 C) for virus multiplication. During incubation of HSV-2-infected cultures at 42 C for 2 to 4 days or after shift-down from 42 to 37 C, incorporation of [3HrTdR into total DNA was increased 2to 30-fold as compared with mock-infected cultures. Analysis of the [3H]DNA suggested that host cell DNA synthesis was induced by HSV-2 infection. Induction of host cell DNA synthesis by HSV-2 also occurred in cells arrested in DNA replication by low serum concentration. The three strains of HSV-2 tested were capable of stimulating cellular DNA synthesis. Virus inactivated by UV irradiation, heat, or neutral red dye and light did not induce cellular DNA synthesis, suggesting that an active viral genome is necessary for induction.

Plants combat their pathogens with an array of defense responses. One of the key mechanisms involves products of resistance (R) genes which are responsible for recognition of effector molecules from pathogens and subsequent triggering of defense responses. Resistance gene analogues (RGAs) containing the specific conserved domains of R-genes are isolated from various plants using degenerate oligonucleotide primer based PCR approach. In an earlier study, RGPM 301 an RGA from pearl millet shown to be involved in resistance mechanism against downy mildew disease was isolated and characterized. In the present study, RGPM 301 containing an open reading frame (ORF) of 992 amino acids was cloned into pRSET A expression vector and expressed in Escherichia coli as a Hig-tag fusion protein. The recombinant RGA RGPM 301 was purified to near homogeneity using the Nickel-CL agarose column. Its molecular mass was found to be 120 kDa when separated on the SDS-PAGE which was confirmed by western blotting analysis using the anti-His antibody. The purified protein was subjected to in-gel trypsin digestion followed by mass spectrometric analysis for the confirmation of its identity. These findings facilitate further studies on the exact role of this RGA in the pearl millet downy mildew host pathogen system.