Frequency distribution of phage release in the one-step growth experiment

Comparison of the mutation rates of human influenza A and B viruses

Human influenza A viruses evolve more rapidly than influenza B viruses. To clarify the cause of this difference, we have evaluated the mutation rate of the nonstructural gene as revealed by the genetic diversity observed during the growth of individual plaques in MDCK cells. Six plaques were studied, representing two strains each of type A and B viruses. A total of 813,663 nucleotides were sequenced, giving rates of 2.0 x 10(-6) and 0.6 x 10(-6) mutations per site per infectious cycle, which, when extended to 1 year, agree well with the published annual evolutionary rates.

Model for bacteriophage T4 development in Escherichia coli

Mathematical relations for the number of mature T4 bacteriophages, both inside and after lysis of an Escherichia coli cell, as a function of time after infection by a single phage were obtained, with the following five parameters: delay time until the first T4 is completed inside the bacterium (eclipse period, nu) and its standard deviation (sigma), the rate at which the number of ripe T4 increases inside the bacterium during the rise period (alpha), and the time when the bacterium bursts (mu) and its standard deviation (beta). Burst size [B = alpha(mu - nu)], the number of phages released from an infected bacterium, is thus a dependent parameter. A least-squares program was used to derive the values of the parameters for a variety of experimental results obtained with wild-type T4 in E. coli B/r under different growth conditions and manipulations (H. Hadas, M. Einav, I. Fishov, and A. Zaritsky, Microbiology 143:179-185, 1997). A "destruction parameter" (zeta) was added to take care of the adverse effect of chloroform on phage survival. The overall agreement between the model and the experiment is quite good. The dependence of the derived parameters on growth conditions can be used to predict phage development under other experimental manipulations.

EFFECTS OF ANTISERUM ON ADSORBED PHAGE

Reiter, Harvard (U.S. Biological Laboratories, Fort Detrick, Frederick, Md.). Effects of antiserum on adsorbed phage. J. Bacteriol. 86: 637–641. 1963.—The penetration of T 3 bacteriophages attached to the host cells could be delayed or entirely prevented by antiserum against T 3 phage. The antiserum-sensitive period of the attached phages increased at lower temperatures. The degree of inhibition increased with antiserum concentration and with early exposure to antiserum. Bacteriophages T 1 and T 4 were not affected by antiserum in this manner; T 7 reacted similarly to T 3 .