Search

The effect of type 5 adenovirus infection on the synthesis of host-cell proteins by suspension cultures of KB cells was investigated. Although total protein synthesis continued at a constant rate for approximately 36 hr, net synthesis of five host enzymes (lactic dehydrogenase, acid phosphatase, deoxyribonuclease, fumarase, and phosphoglucose isomerase) was found to stop 16 to 20 hr after infection. The synthesis of alkaline phosphatase stopped 9 to 12 hr after infection. The inhibition of host protein synthesis occurred shortly after the synthesis of viral antigens had begun, accounting for the continued synthesis of total protein. An investigation of the relationship between synthesis of viral antigens and inhibition of host protein synthesis yielded results which suggest that the two processes are in some way coupled.

Previous results have shown that infection of KB cells with type 5 adenovirus elicits the inhibition of host protein synthesis. In an attempt to determine whether inhibition is caused by a block in the transcription of host deoxyribonucleic acid (DNA), the rate of synthesis of host DNA-like ribonucleic acid (D-RNA) was compared with the rate of host protein synthesis at various times after infection. The rate of host D-RNA synthesis was determined by measuring the rate of incorporation of (3)H-uridine into species of ribonucleic acid which could hybridize specifically with KB cell DNA. The rate of host protein synthesis was determined by measuring the rate of incorporation of (14)C-valine into species of protein which could not be precipitated by antiserum directed against viral antigens. The results obtained suggest that the primary event producing inhibition of host protein synthesis is not the inhibition of transcription of host DNA. Synthesis of viral D-RNA in type 5 adenovirus-infected KB cells was next examined. Synthesis was first detected 8 to 10 hr after infection, and it could not be detected if viral DNA synthesis was blocked. At those times when inhibition of host protein synthesis was evident, the rate of synthesis of viral D-RNA appeared to exceed that of KB cell D-RNA.