Louis P. Gebhardt

Morphological transformation of Candida albicans in tissues of mice.

Summary A morphological alteration of yeast-like cells of C. albicans and C. stella-toidea has been shown to occur within 1 hour after injection into the subcutaneous tissues of mice. Yeast-like cells of other members of the genus Candida failed to exhibit these alterations under the same conditions. The yeast-like cells of C. albicans had formed elongated pseudomycelia within 1 hour after injection. At later times considerable growth of these filaments with the appearance of septa was observed. Other species of the genus Candida retained their typical yeast-like morphology. It has been postulated that filamentation of C. albicans in vivo serves as a hindrance to ingestion by mouse phagocytes. The results suggest a significant role for these morphologically altered organisms in the pathogenesis of experimental moniliasis in the mouse.

The Primary Interaction of Poliomyelitis Virus with Host Cells of Tissue Culture Origin.

Abstract The inorganic salts CaCl2 and MgCl2 promoted the attachment of poliomyelitis virus to monkey kidney tissue culture cells in suspension. The rate of virus attachment was found to be dependent on the concentration of these salts. No attachment was demonstrable at 10−1 M or higher and 10−5 M or lower concentrations of the above salts. Optimal attachment rates occurred at 10−3 M calcium or magnesium chloride. Temperature exerted no significant effect on the virus attachment rate within the range of 37° to 1°. A nonadsorbing system of virus and cells was converted into a rapidly reacting one by the addition of CaCl2 to a final concentration of 10−3 M. These data suggested that the initial binding of poliomyelitis virus to host cells is mediated through electrostatic bonding.

Overwintering of Western Equine Encephalitis Virus.

Summary 1) Adult garter snakes (Thamnophis spp.) inoculated intraperitoneally, overwintered WEE virus for at least 139 days. There was a steady decline in virus, with only 1 of 14 showing a viremia after 92 days hibernation. With warm spring weather, (139 days after virus inoculation) 9 of 14 animals exhibited a viremia with blood titers varying from 10-1 to 10-3.5. 2) Two of 4 garter snakes inoculated with WEE virus and kept at 4°C, for 17 days harbored the virus in the blood, but not the brain. One snake harbored the virus in the brain but not in the blood. No virus was detected in either blood or brain after 17 days at 4°C in one of the snakes.

A Method for the Demonstration of Tissue Antibody.

Summary A direct slide agglutination technic is described for determining the presence of agglutinating antibody in air-dried films of tissues and cells. This method has proved to be of value in correlating the appearance of antibody with cytological changes occurring at the site of antibody production.

Transmission of WEE Virus to Snakes by Infected Culex tarsalis Mosquitoes.

Summary Of 12 snakes offered as blood meal sources for 18 infected mosquitoes, seven of these poikilothermic animals responded with a viremia. Six developed titers of 105 or more, while one developed a viremia of only 1.45 × 102 PFU per ml of blood. Two developed titers of 107 and one 108 PFU per ml of blood. Five developed a viremia within one to three days, while one was delayed to the 9th day and one was delayed to the 17th day after being bitten. The virus content of the mosquito biting the snake appeared not to be a determining factor whether the snake became infected or not. When snakes were exposed to a single infected mosquito each, 4 of 8 became viremic. When snakes were exposed to 2 or 3 infected mosquitoes each, 3 of 4 became viremic.

Effect of sodium monofluoroacetate on multiplication of Eastern equine encephalomyelitis virus.

Summary The reduplication of Eastern equine encephalomyelitis virus in mouse brain is delayed in mice previously treated with sodium monofluoroacetate. This chemical seems to prolong the survival time of the infected animals, although it does not otherwise alter the course of infection. In high concentration, the chemical has no direct effect in vitro on the infectivity of the virus, nor does it show an in vivo effect on the susceptibility of the host to the infection with this virus.

Effect of Eastern Equine Encephalomyelitis Virus Infection on Phosphate Transfer and Modification by Cortisone.

Summary Infection of mice with virus of Eastern equine encephalomyelitis induced an enhanced rate of phosphate transfer from blood to brain tissues, which could be markedly reduced by pretreatment of the infected animals with cortisone. Non-specific alteration of phosphate transfer to brain tissue could also be suppressed to a similar degree by cortisone treatment. Comparison of the E.E.E. virus growth in both cortisone-treated and untreated animals showed no effect of cortisone on rate of virus proliferation. The effect of this neurotropic virus infection on rate of phosphate transfer from blood to brain acid-soluble phosphates appeared to be due to inflammation, rather than to a specific metabolic requirement for virus synthesis.

Chemoprophylaxis and Chemotherapy of Experimental Poliomyelitis.

Summary 1. Two of 19 monkeys (10.5%) developed poliomyelitis when treated prophylactically with 4-amino-1-naphthol HCl (Naphtoholic derivative). 2. One sample of gallic acid, technical (E-1) (Phenolic derivative) prophylactically protected all of the 12 monkeys treated. A second sample of gallic acid, technical (E-2), freshly prepared, failed to exhibit prophylactic protection. Its mother liquor, however, stored for 50 days allowed only one animal of eleven to develop the disease, when used prophylactically. Of 14 monkeys treated prophylactically with p-aminophenol, 3 developed poliomyelitis. 3. When used therapeutically, both gallic acid, technical (E-1) and mother liquor (E-2) of technical gallic acid, stored at 4°C from one week to 3 months, and given to monkeys beginning 5 days after virus, 7 of 53 monkeys (13%) developed the disease, whereas 47.1% of the controls developed the disease.

Reproducible oral infection rates in monkeys with the Mahoney strain (Type 1) of poliomyelitis virus.

Summary A method of orally infecting cynomolgus monkeys is presented. Consistent and reproducible infections (56%) have been obtained using the Mahoney strain (Type 1) poliomyelitis virus mixed with cream (12% fat) and introducing the virus-cream mixture into the stomach by means of a Fr. No. 16 urethral catheter in a single dose.

Guinea pig antibody response following a secondary injection of Coxiella burnetti.

Summary Secondary Q fever antibody responses using Phase I and II complement fixing antigens were determined in guinea pigs after intraperitoneal, secondary injection 125 weeks later. As compared with non-secondarily injected controls, a slight negative antibody phase was observed, followed by significant antibody titers, these titers corresponding in magnitude to the number of organisms injected.