SUMMARY: Extracts of 288 plants, mostly British, were examined for suppressive action on the development of a bacteriophage of Pseudomonas pyocyanea. Many possessed this property and eight of them suppressed the growth of phage at concentrations less than one-tenth of those which affected the growth of the host, Ps. pyocyanea.Extracts from 142 of the plants were tested against Influenza A virus in embryonated eggs and twelve of them suppressed virus multiplication. All extracts active against Influenza A virus were also active against the bacteriophage. Four extracts tested against Influenza A in mice were inactive. Eight extracts were investigated further; these were inactivated by proteins and were only active when in direct contact with the virus in protein-free media, Activity was closely associated with the tannin content of the extracts and could not be separated from it. Commercial tannins were also highly active in protein-free media. At some stages of our work the identification of the samples was unable to keep up with the rate of supply, and although a portion of the plants was always kept for examination it was not always possible to decide upon the specific name. Difficulty also arose when an extract from a florist's variety was under test. In both these cases the generic name followed by (?sp.) appears in Table 7. In some cases several varieties of the same species were tested. METHODS Preparation of extractsPlants in as fresh a condition as possible were macerated in distilled water plus 15 yo (v/v) industrial spirit, using a bench macerator with high-speed

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The epizootiology of equine herpesvirus type 2 (EHV-2) infection was investigated in Thoroughbred foals on a stud farm which in previous years had suffered economic loss due to respiratory disease. Sixteen pairs of foals and their dams were selected for this study and all of the foals became infected with EHV-2 by two to four months of age. These animals responded serologically to the virus infection as detected by an enzyme-linked immunosorbent assay (ELISA). EHV-2 infection persisted in these foals for two to six months with constant or intermittent virus recovery. This persistent infection stimulated continuous production of antibodies against EHV-2. As soon as the antibody levels reached their peak at five to six months, the isolation rate of EHV-2 from the nasal cavity of these animals decreased, and eventually by nine months of age virus could no longer be recovered. Respiratory disease was observed in ten of the 16 foals; and two severely affected animals died at two months of age. EHV-2 was isolated from both foals at ante and/or post mortem examination. It is postulated that EHV-2, either as an initiating agent or by means of immnunosuppression, caused the respiratory disease observed in these foals.

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SUMMARY: Two new compounds inhibited the increase of phage when two phages of Pseudomonas pyocyanea were grown on an indicator strain. These compounds also inhibited the appearance of iridescence in a lysogenic strain of this organism.One iridescent lysogenic strain showed a rise in phage titre a t 1&2 hr., which corresponded to the latent period of the phage when it acted on an indicator strain.Both these increases were inhibited by the compounds. This lysogenic strain also showed a rise in phage titre a t 4 hr. but this was unaffected by the compounds. The final phage titre of the lysogenic culture was not affected significantly, unlike the complete and permanent suppression of phage increase when free phage acted on an indicator strain. Cultures and filtrates of three lysogenic strains of Ps. pyocyanea showed a great increase in phage titre when assay plates (against an indicator strain) were incubated for a further period after the initial reading a t 18 hr.Many workers have described iridescent strains of Pseudomonas pyocyaneu. Warner (1950) gave a. detailed description and concluded that the iridescent clearing was not caused by bacteriophage action but was a distinct lytic phenomenon, probably the result of bacterial variation. Don & van den Ende (1950) studied thirty strains of Ps. pyocyama with particular reference to the metallic lytic effect and bacteriophage action but the relationship, if any, between these two effects remained obscure. Following an investigation of drug action on the phages of Ps. pyocyanea (Dickinson, 1948), an explanation was sought for the lack of action of drugs on phages associated with iridescent cultures of this organism. It was decided to investigate the reproduction of phage in one of these cultures. The present paper reports this work and includes observations which correlate iridescence with bacteriophage action in this particular strain.The following abbreviations and definitions are used in this paper.