Initiation Of Viral Replication Research Articles

The multiplication of Sericesthis iridescent virus in cell cultures from Antheraea eucalypti Scott : III. Quantitative experiments

SIV was not dissociated from infected Antheraea eucalypti cells by washing at times later than 10 hours after inoculation. Viral DNA was synthesized in cytoplasmic foci which also contained antigen. Each infective unit (IU) of virus formed a separate focus, but supernumerary foci were formed in some cells. The initiation of viral replication was a random process consistent with Cairns' (1960) theory of asynchrony. Once replication was initiated in a multiply infected cell, all the foci began to operate at about the same time. Synthesis of viral DNA and antigen was detected in some cells 2 days after inoculation; most infected cells had begun viral replication by 6 days and continued to synthesize viral DNA for a further 2 days. Inhibition of host cell nuclear DNA synthesis was not a prerequisite for viral DNA synthesis. Infective virus was eclipsed for about 4 days after inoculation and was then continuously produced and released from the cells until the 8th day. The yield was about 500 IU per infected cell, of which about 360 IU/cell was released. SIV was ether resistant. It is proposed that iridescent viruses from a group separate from adenoviruses.

AMINO ACID IMBALANCE AND INCOMPLETE VIRAL REPLICATION.

Four amino acids, lysine, leucine, tryptophane, and phenylalanine, at concentrations of 0.5 to 5.0 mg./ml. inhibit the production of influenza viral hemagglutinins and complement-fixing S antigen in Krebs 2 ascites cells suspended in a medium containing only glucose and glutamate as substrates. In Krebs 2 cells no new infectious virus is formed but the hemagglutinins and CF antigen are produced in high yield. The latter antigen is less sensitive than the hemagglutinin to amino acid imbalance. At minimal inhibitory concentrations of these amino acids formation of viral hemagglutinins was reduced to a much greater extent than cellular protein synthesis. Selective reversal of inhibition was demonstrated, except for leucine, by a survey of the effects of adding each of 18 other amino acids at non-inhibitory concentrations. The effective ratios of reversing amino acid to inhibitor varied from 1∶5 to 1∶100. Certain d-amino acids were much less active than the corresponding l-isomers as inhibitors or reversers. The kinetics of inhibition and reversal suggest that the principal effect of amino acid imbalance may be on the formation of enzymes essential to the initiation of viral replication, but, depending on the amino acid and its concentration, other mechanisms af action are possible.