A PHAGE INFECTING SAPROSPIRA GRANDIS

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ELECTRON MICROSCOPY OF IN VITRO ENDOCYTOSIS OF T2 PHAGE BY CELLS FROM RABBIT PERITONEAL EXUDATE

Macrophages from rabbit peritoneal exudate cells incubated in vitro with T₂ bacteriophage from 10 up to 120 minutes show phage particles adsorbed to cell membranes, in the process of being engulfed by means of rhopheocytosis, micropinocytosis, and phagocytosis, and localized within dense vacuoles, semi-dense vacuoles, and clear vacuoles of the cytoplasm. The electronmicrographs suggest that newly formed endocytic vacuoles containing phage particles fuse with one another and also fuse with dense bodies of the cytoplasm as they migrate towards the cell interior, thus yielding larger vacuoles of varying densities containing higher concentrations of phage. The polymorphonuclear cells present in a small proportion in the peritoneal exudate cells also endocytosed phage particles. The T₂ particles are found in large cytoplasmic vacuoles surrounded by an electron-opaque material presumably derived from cytoplasmic granules. No disintegration of T₂ phage within the macrophage following incubations up to 120 minutes could be demonstrated; however, disrupted phage particles were noted within cytoplasmic vacuoles of polymorphonuclear leucocytes after 15 minutes' incubation.

CHROMATOGRAPHIC SEPARATION OF ANNEALED AND ENZYMATICALLY SYNTHESIZED RNA-DNA HYBRIDS

A procedure is described for the chromatographic detection and isolation of DNA-RNA hybrids on columns of methylated albumin coated on kieselguhr (MAK). Its use is illustrated with both annealed and enzymatically synthesized hybrids. The method has the advantage of a wide range in capacity and resolution and permits actual isolation of the hybrid structure. It is uniquely effective in experiments involving hybridization with small DNA fragments.

IMMUNOLOGIC INCOMPETENCE OF IMMUNOLOGICALLY RUNTED ANIMALS

1. Adult (A x C(57)Bl/1)F(1) hybrids regularly show runt disease when injected with adult spleen cells from A strain donors. This also occurs when A strain spleen cells are administered to adult C(3)H mice made tolerant of A strain tissue in the neonatal period. 2. Mice undergoing the graft versus host reaction fail to form antibodies to an intraperitoneal challenge of T(2) bacteriophage. This phenomenon was observed well before any of the other overt signs of runting had occurred. Further, inhibition of antibody production to T(2) phage by graft versus host reaction initiated at an interval following antigenic stimulation is demonstrated. 3. The basis for the immunologic incompetence of the host with respect to T(2) phage is presumed to be the attack of immunologically competent donor cells on the lymphoid cells of the recipient. 4. The failure of the injected parent strain cells to respond to the antigen used may imply immunologic commitment of these cells.

EFFECTS OF ENVIRONMENTAL FACTORS ON THE SURVIVAL OF AIRBORNE T-3 COLIPHAGE

Experiments were conducted to determine the effects of storage temperatures, relative humidity, and additives on the survival of aerosolized Escherichia coli phage T-3. The aerosol stability of the coliphage, calculated as per cent recovery, was not affected by storage at 10 or -70 C for up to 4 months. However, an increase in aerosol decay rate of coliphage stored at 10 C was observed. The effect of humidities ranging from 20 to 90% relative humidity was studied, and it was observed that humidities lower than 70% relative humidity significantly reduce the survival of airborne coliphage. The effect of various compounds on the aerosol decay rate of T-3 coliphage was studied at 50 and 85% relative humidity. Addition of dextrose in 0.1 M concentrations to the disseminating fluid significantly reduced aerosol decay rate at 50% relative humidity without affecting the decay at 85%. Addition of spermine, spermidine-phosphate, thiourea, galacturonic acid, and glucosaminic acid, individually or in combination, had no effect on aerosol decay rates. The use of deuterium oxide as the suspending fluid for dissemination had no effect on aerosol stability of the coliphage.