Relation between adsorption of diphtheria phage and its inactivation by an oleic acid-activated inhibitor

Insights into virus inactivation by polysorbate 80 in the absence of solvent

Triton X-100 has long been used either alone or in combination with solvent to inactivate enveloped viruses in biopharmaceutical manufacturing. However, European Chemicals Agency (ECHA) officially placed Triton X-100 on the Annex XIV authorization list in 2017 because 4-(1,1,3,3-tetramethylbutyl) phenol, a degradation product of Triton X-100, is of harmful endocrine disrupting activities. As a result, any use of Triton X-100 in the European Economic Area would require an ECHA issued authorization after the sunset date of January 4, 2021. In search of possible replacements for Triton X-100, we discovered that polysorbate 80 (PS80) in absence of any solvents was able to effectively inactive enveloped viruses such as xenotropic murine leukemia virus and pseudorabies virus with comparable efficacy as measured by log reduction factors. Interestingly, PS80 did not show any virucidal activities in phosphate buffered saline (PBS) while achieving robust virus inactivation in cell-free Chinese hamster ovary (CHO) bioreactor harvests. This intriguing observation led us to speculate that virus inactivation by PS80 involved components in the cell-free CHO bioreactor harvests that were absent in PBS. Specifically, we hypothesized that esterase and/or lipases in the cell-free bioreactor harvests hydrolyzed PS80 to yield oleic acid, a known potent virucidal agent, which in turn inactivated viruses. This theory was confirmed using purified recombinant lysosomal phospholipase A2 isomer (rLPLA2) in PBS. Subsequent characterization work has indicated that virus inactivation by PS80 is effective and robust within temperature and concentration ranges comparable to those of Triton X-100. Similar to Triton X-100, virus inactivation by PS80 is dually dependent on treatment time and temperature. Unlike Triton X-100, PS80 inactivation does not correlate with concentrations in a simple manner. Additionally, we have demonstrated that PS20 exhibits similar virus inactivation activities as PS80. Based on the findings described in the current work, we believe that PS80 is potentially a viable replacement for Triton X-100 and can be used in manufacturing processes for wide spectrum of biopharmaceuticals to achieve desirable virus clearance. Finally, the advantages and disadvantages of using PS80 for virus inactivation are discussed in the contexts of GMP manufacturing.

Variation among strains of Coynebacterium diphtheriae during an outbreak in a restricted environment

Strains of Corynebacterium diphtheriae isolated from a small outbreak in the restricted environment of a Mental Hospital were examined. All belonged to one serotype, but there was marked variation in diphthericin type, in sensitivity to bacteriophages and in the minor antigens possessed. One strain was non-virulent and laboratory-produced variants of this non-virulent strain showed changes in some of the characteristics used in the identification and typing of the organism, such as diphthericin type, sensitivity to bacteriophages and diphthericins, virulence, starch fermentation and, to a lesser extent, in antigenic structure. The epidemiological and experimental findings are consistent with the hypothesis that the strains isolated, both in the hospital and in the laboratory, were derivatives of a single parent and the mechanism of some of the variations could be related to changes in some structural component such as the cell membrane or the cell wall.

Distribution of neuraminidase and n-acetylneuraminate lyase activities among corynebacteria, mycobacteria, and nocardias

In Corynebacterium diphtheriae and closely related neuraminidase-producing corynebacteria, we have found an N-acetylneuraminate (NAN) lyase activity which cleaves NAN into N-acetyl-d-mannosamine and, presumably, pyruvate. In vitro, these lyases can be shown to synthesize NAN. A survey of representative corynebacteria, "plant pathogenic corynebacteria," mycobacteria, and nocardias revealed that only those corynebacteria closely related to C. diphtheriae exhibited both neuraminidase and NAN lyase activities.

Inactivation of nocardiophages phi C and phi EC by extracts of bacteriophage-attachable cells

Cultures of several species of Nocardia, including N. erythropolis Mat-Ce and Mat-cE mating strains, were extracted with solvents in an attempt to isolate an inactivating complex for nocardiophages phiC and phiEC. Ethanol was the only solvent found effective in solubilizing an inhibitory substance. Inactivating extracts were obtained from the cells of all species to which the phage were able to attach. After extraction of whole cells or cell wall preparations, the phage could not effectively attach to them. Both phages phiC and phiEC were inactivated by the same complex. However, phage phiEC inactivation was 10-fold greater than phiC inactivation. The velocity of inactivation was about 4.1 x 10(2) plaque-forming units per microgram per minute for phiC and 1.1 x 10(3) plaque-forming units per microgram per minute for phage phiEC. The cell extracts required divalent cations for phage inactivation. The inhibitory capacity of the cell extracts was reduced or lost by the activity of proteolytic enzymes, Tween 80, 2-mercaptoethanol, thymol, and sodium lauryl sulfate. Boiling the extract for 10 min did not alter its activity. The inactivating substance was postulated to be a lipoprotein of considerable complexity, unique in the ease with which it is solubilized from host cells by ethanol.

Park-Williams number 8 strain of Corynebacterium diphtheriae

Five clones of the Park-Williams number 8 strain of Corynebacterium diphtheriae, previously maintained in separate laboratories, were examined for their colonial and biochemical properties, for the restriction and modification system which operates to obscure their lysogeny, and for their capacity to produce large amounts of toxin under ordinary laboratory conditions. The phenotypes of their phage, P, produced in strain 603 and C7 (P.603 and P.C7) differ both as to stability to storage in the cold and to inactivation by antiphage serum. Evidence for a high degree of stability in the integration of P prophage in the PW8 genome is presented.

Corynebacterium diphtheriae and its relatives

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Comparative studies with tox plus and tox minus corynebacteriophages

The characteristics of nine inducible temperate corynebacteriophages designated alpha(tox+), beta(tox+), P(tox+), gamma(tox-), pi(tox+), K(tox-), rho(tox-), L(tox+), and delta(tox+) have been compared. Virion morphology and ability to recombine genetically with the well-studied phage beta(tox+) have been correlated with other properties of the phages, and the distribution of the genetic marker tox+ among related and relatively unrelated corynebacteriophages has been analyzed. The immunity specificity, host range, and plaque morphology of each phage were determined. The phages can be separated into five groups with different immunity specificities. Each type of host range previously recognized in mutants of phage beta(tox+) was present in one or more of the phages included in the present study, and the phages were found to produce plaques of several different morphological types. Representative phages with each of the five types of immunity specificity were further characterized with respect to virion morphology, ability to recombine with phage beta(tox+), latent period, average burst size, and neutralization by homologous and heterologous antiphage sera. All of these phages have polyhedral heads and long slender tails, but two distinct morphological types were distinguished by the sizes and proportions of the components of the virions. Only phages of the same morphological type as beta(tox+) were capable of genetic recombination with beta(tox+), but morphological similarity between phages was not sufficient to insure interfertility. The phages which recombined with beta(tox+) resembled one another in plaque morphology, latent period, and average burst size, whereas phages which failed to recombine with beta(tox+) differed in these characteristics. The phages capable of genetic recombination with beta(tox+) were found to differ from each other in immunity specificity, host range, neutralization by antiphage sera, and toxinogenicity. Thus, these latter characteristics are of limited value in establishing the extent of relatedness between corynebacteriophages. The genetic marker tox+ was not consistently correlated with any other property of the corynebacteriophages analyzed in this study. The most striking finding regarding the distribution of the tox+ marker is its presence both in beta(tox+) and delta(tox+), phages which fail to recombine genetically and which differ in virion morphology. The presence of the tox+ marker in genetically unrelated corynebacteriophages poses many questions concerning the origin(s) of tox+ and the evolution of the phage-host interactions which determine the ability of corynebacteria to synthesize diphtherial toxin.