关键词： Science   Humanities and Social Sciences   multidisciplinary  

摘要： INFECTION of animal cells with one type of poliovirus interferes with the growth of another, superinfecting, type added 30–60 min later1,2. On the other hand, simultaneous infection with type 1 and type 2 polioviruses can result in both types of viral RNA growing in the same cell, and in a considerable degree of phenotypic mixing in the progeny3,4. This communication describes a case of interference between two strains of poliovirus after simultaneous infection at equal multiplicities.

关键词： Science   Humanities and Social Sciences   multidisciplinary  

摘要： IN previous work we have described the effect of two amino-aeid analogues on the replication of Western equine encephalitis virus (WEE)1 and poliovirus2. Para-fluorophenylalanine (FPA) was shown to reduce cellular protein synthesis if used at sufficiently high concentrations1. Under these conditions FPA also inhibited the appearance of infectious viral RNA and viral antigens2. In contrast, FPA at low concentrations did not inhibit the synthesis of protein in the infected cell nor did it inhibit the formation of infectious RNA of WEE and poliovirus2'3. However, no infectious virus was formed, and it was found that this was most likely due to the incorporation of the amino-acid analogue into viral proteins (ref. 3, ef. ref. 5). Another amino-acid analogue- ethionine-which is always incorporated and even at high concentrations does not inhibit protein synthesis significantly produced effects on WEE virus formation similar to those of FPA at low *** it was suggested that the synthesis of aberrant proteins due to the incorporation of amino-acid analogues is still compatible with the proper formation or preservation of infectious viral RNA (ref. 5). On the other hand, any substance which actually inhibits the mechanism of protein synthesis, such as FPA at high concentrations, might be expected to interfere with the appearance of infectious RNA in the *** puromycin is a powerful inhibitor of protein synthesis (cf. refs. 3 and 5) and has a mechanism of action supposedly quite different from that of amino-acid analogues6"7, its effect on the appearance of infectious RNA of WEE and polio was examined. Fig. 1 shows the dose response curves to puromycin of virus maturation and appearance of infectious RNA in the case of WEE. Virus maturation is more sensitive to the inhibitor than the synthesis of infectious RNA, although the differences are somewhat less pronounced than with FPA (ref. 2). Puromycin at 7-5 [ig/ml. can also inhibit completely the appear

关键词： Science   Humanities and Social Sciences   multidisciplinary  

摘要： THE neutralizing or inhibitory action of some bovine sera to one or more of the three serological types of polio virus has been described by a number of workers1-5. Bartell and Klein3 found that this property was also possessed by the sera of certain horses, pigs and chickens, and that the activity was associated with the globulin fraction of the sera. McFerran5 demonstrated that the bovine polio virus inhibitors had much the same stability as polio virus antibodies in human sera, and concluded, as did Bartell and Klein, that they were probably antibodies, the origin of which was obscure. In marked contrast were the conclusions of Takemoto and Habel6 with regard to equine serum poliovirus inhibitors; they regarded the action of the serum as being not neutralization but a reduction in the rate of adsorption and release of virus from the cells of the tissue culture system. Fractionation on the cellulose column, however, indicated that the activity was associated with the ***. 1. Neutralization of polio viruses by equine inhibitory seraIn this article, studies of poliovirus inhibitors of equine sera are presented and the frequencies of their occurrence analysed. A survey of inhibitors of sheep and monkey sera is also included, and suggestions as to the origin of poliovirus inhibitors are made. Monolayer monkey kidney tissue cultures were used for this work and wrere maintained on Earle's salt solution containing 0-5 per cent liver digest, 0-22 per cent sodium bicarbonate and penicillin and streptomycin. Poliovirus strains Brunenders, MEF-l and Saukett were used unless otherwise *** horse, sheep and monkey sera were tested for inhibitors by mixing doubling serum dilutions with polio-virus (100 T(7D50/0-5 ml. of mixture), incubating 1^ h at 37 C, inoculating 0-5 ml. of each reaction mixture into four monkey kidney tube cultures and examining for cytopathic effect six days later. The percentages of sera showing inhibition are given in Table 1. In ea

关键词： GUANIDINES   POLIOMYELITIS  

关键词： EXPERIMENTAL LAB STUDY   FORMALDEHYDE   KINETICS   PHARMACOLOGY   POLIOVIRUS  

摘要： It is shown that the non-first-order course of the formalin inactivation of poliovirus is consistent with the kinetic requirements of a mechanism of the type, Nn [image] nN [forward arrow] nD. In this formulation, Nn represents a non-infectious n-meric form of the virus, N is the infectious native form of the virus, and D is an antigenie but non-infectious species. The method used for testing the applicability of this mechanism is discussed in some detail. Several respects in which the postulated mechanism is related to previous proposals are also examined, especially the possible role of a superimposed thermal denaturation.

关键词： Medical Microbiology   Immunology   Virology  

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关键词： Poliovirus   RNA   Inoculum   Amino acids   Inoculation   Serial passage   Adsorption   Washing   Temperature dependence  

摘要： A high concentration (2 to 6m[image]) of L-tryptophan inhibited wild type virus of the Mabie strain of antigenic type 3 pollovirus. Passages on cells under a medium containing 2 m[image] L-tryptophan resulted in the emergence of a mutant which required a high concentration of L-tryptophan. The effect of L-tryptophan on the mutant was manifested at about 35[degree]C by an increase in plaque size and at about 37[degree]C by a 100-fold increase in the number of plaques produced. With increasing temperature the mutant required increasing amounts of L-tryptophan. The requirement was most clearly defined when plaques developed under a medium of somewhat low pH (7.0 to 7.5). High L-tryptophan also increased the number of progeny produced by the mutant. Genetic revertants from the mutant to viruses like, or nearly like, the wild type occurred and were rapidly selected at 37[degree]C with low L-tryptophan. Plaque development by the mutant was not promoted by D-try ptophan or any one of 8 other compounds but was promoted by DL-5-methyltryptophan or indole- 3- acetic acid. Anthranillc acid and phenylalanine had slight activity. L-tryptophan was apparently required for some postadsorptive phase in the infectious process. The responses of the mutant to 2 other amino acids (L-cystine and L-histi-dlne) were like wild type. Progeny in plaques produced by rlbonuclease-labile infective units obtained from wild type and mutant virus had responses to L-tryptophan like wild type and mutant, respectively. Thus, the genetic basis for the mutant''s L-tryptophan requirement probably lies in the specific structure of its ribonucleic acld.

关键词： Science   Humanities and Social Sciences   multidisciplinary  

摘要： Newton and Bevis1 concentrated some animal viruses by adding zinc hydroxide to the virus suspension and afterwards dissolving the gel in saturated ethylenediamine tetraacetic acid solution in order to recover the virus. Attempts made in our laboratory to concentrate poliovirus by this method yielded unsatisfactory results.