An immune ribonucleic acid (RNA) preparation was obtained from the spleens of mice immunized with a live vaccine of Salmonella enteritidis. When peritoneal macrophages were infected with S. enteritidis 116-54 which had been treated by mixed cultivation with the peritoneal exudate cells of mice previously treated with an immune RNA preparation, they showed cellular resistance against the infecting bacteria, According to the results described previously and those described in this article, it can be concluded that the cellular resistance against an infection with S. enteritidis is traceable to a cellular antibody (or antibodies) detected in macrophages of mice immunized with a live vaccine of the same organism or of mice treated in viva (or in vitro) with an immune RNA preparation.

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The Wassermann antigen is a lipid micelle, and the essential component of the hapten is cardiolipin. It requires the addition of lecithin and cholesterol as auxiliary lipids. We conducted a study on the role of auxiliary lipids in the formation of the micelle structure using negative staining and observing with the electron microscope. The following results were obtained: (1) Cardiolipin, when dispersed in Mg-NaCl solution, presented an irregular network structure. Lecithin, on the other hand, revealed a regular lamellar structure. Cholesterol, since it is nonpolar, immediately agglutinated and precipitated when suspended in the aqueous system. (2) A combination of cardiolipin and lecithin presented a regular lamellar structure, but no network structure of eardiolipin was observed in the visible field. The combination of cardiolipin and cholesterol revealed eardiolipin surrounding structureless cholesterol with its network structure. The combination of lecithin and cholesterol exhibited a lamellar structure surrounding the cholesterol. (3) A combination of all three revealed a variegated picture of a lamellar structure formed by cardiolipin and lecithin surrounding the cholesterol as a core or of onionskin-like micelles attached to the above structure.

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The present authors reported strain differences among various mouse strains in antibody production against hamster erythrocytes (HRBC) in a previous paper (SL_??_CFl>DDD>C3H/He_??_AKR>C57-BL/6). This study was undertaken to determine whether or not a strain difference existed in the ability of mouse macrophages to take up HRBC. Macrophages of the high-responder DDD, intermediate-responder AKR and low-responder C57BL/6 mice were tested. 1) Normal macrophages from these three strains exhibited similar degrees of attachment and ingestion in the presence of normal AKR serum in the medium. 2) Normal sera from DDD and C57BL/6 mice conferred the same degree of opsonizing activity on normal AKR macrophages in in vitro experiments. 3) When HRBC were injected into the peritoneal cavities of normal DDD and C57BL/6 mice, almost the same degrees of attachment and ingestion were detected in their macrophages. 4) When the antibodies to HRBC were present in in vivo or in vitro experiments, macrophages of DDD and C57BL/6 mice actively took up HRBC to similar degrees. These results led us to conclude that macrophages of the high- and low-responder mice took up HRBC to the same degrees after primary immunization.

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Estimations were performed on the numbers of Clostridium perfringens in 1-ml samples of fecal specimens collected from 30 healthy aged adults. These measurements were repeated 15 times for each individual during a 16-week period. Most of the fecal samples proved to consistently contain more than 10⁵ C. perfringens cells and the majority of aged adults were observed to carry over 10⁶ cells of this organism on more than eight testing occasions. Few adults were revealed to carry over 10⁷ cells with fairly strong a-toxigenicities without any clinical symptoms. An attempt to decrease the numbers of organisms pre sent by continued drinking of a commercial product containing live lactobacilli resulted in failure, whilst a gradual increase in the numbers of lactobacilli and a decrease in the numbers of Bacteroides were observed. Most infants when examined for the numbers of C. perfringens in a 1-ml portion of their fecal specimens, showed less than 102 cells of this organism and when given the Lactobacillus preparation per os exhibited a rapid increase in the numbers of lactobacilli in their intestinal contents.

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Preincubation of Newcastle disease virus (NDV)-infected RK13 cells at 37 C considerably en-hanced subsequent interferon (IF) production at 25 C. The optimal length of this preincubation was about 7 to 9 hr. It was postulated that the intracellular events leading to IF production in NDV-in-duced cells might proceed in two distinct phases, early and late; the early phase to prepare the cells for IF synthesis proceeds only at 37 C whereas the late phase in which IF is readily synthesized occurs both at 37 C and at 25 C. Similar events seemed to occur in cultures of cells from in vivo induced rabbits. This concept was substantiated by experiments using actinomycin D and cycloheximide, which sug-gested that protein synthesis at 37 C during the first 7 hr was essential for subsequent IF production at 25 C. A prolonged preincubation at 37 C resulted in decreased IF production, suggesting that a puta-tive regulatory protein might be synthesized at 37 C which could not be readily synthesized at 25 C.

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Pretreatment of mouse L cells with interferon (IF) preparations enhanced IF production in response to stimulation with polyinosinic-polycytidylic acid (poly I·poly C). The enhancement of IF production by the pretreatment was maximal with 5 to 10 units/ml of IF. Pretreatment with approximately 1 unit/ml of IF caused no significant enhancement. The enhancement was observed with all IF preparations tested, crude or partially purified, prepared by induction with either poly I·poly C, Escherichia coli endotoxin or Newcastle disease virus. IFs harvested at different times after induction with high and low concentrations of poly I·poly C were equally effective. The enhancing ("priming") activity exhibited "species specificity." However, pretreatment with a high dose of human or rabbit IF, which showed an activity of about 10 units/ml even in the heterologous L cells, enhanced mouse IF production. Studies on physicochemical properties of the active factor indicated that the "priming" activity may be ascribable to IF molecules and not to any other factor in the IF preparations.

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Four kinds of H antigenic particles (H particles) of poliovirus were prepared, (1) by mild alkaline treatment of virions (Alkaline-H), (2) by separation from the virus infected culture (Natural-H), (3) by ultraviolet irradiation of virions (UV-H), (4) by heating of virions (Heat-H). They were examined for sensitivity to an alkaline degradation (pH 10.5 at 40 C). Heat-H was most stable and no degradation of capsid was observed after the treatment. UV-H was most unstable, since it was completely disrupted into small components after the treatment. Alkaline-H and Natural-H were relatively stable but a minor amount of small component(s) was liberated therefrom by the treatment. These results suggest that the H particles induced by the four procedures are different from each other in the stability of capsid structure. Furthermore, it is suggested that the antigenicity(s) of the small-size component(s) is different from either N or H antigenicity being ascribable to VP2 polymer.

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Herpes simplex virus strains isolated from genital and nongenital sites were classified into type 1 (HSV-1) and type 2 (HSV-2) by endpoint neutralization tests using IgM of rabbits hyperimmunized with either HF (HSV-1) or UW-268 (HSV-2) strain. It was found that about one-third of the genital isolates belonged to type 1, in contrast to the general concept that HSV-2 represents genital herpes strains. These HSV-1 strains, differing from HSV-2, were mostly isolates from acute herpetic lesions of female patients with constitutional symptoms. On the other hand, all nongenital isolates except one were determined to be HSV-1. There was no intermediate type equally neutralizable by both types of IgM. A majority of the HSV-2 strains produced large plaques in chick embryo (CE) cells before passage through avian cells. In contrast, all HSV-1 strains failed to produce such large CE plaques even after serial passages through avian hosts.

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Newborn hamsters were inoculated with human adenovirus type 12 (Ad12) within 24 hr of birth for tumor induction, and 15 days later, intercurrently immunized with Ad12-infected cells (KB; HeLa; FL; HEK; MoE; HaE). Tumor development was then observed for 75 days thereafter. Tumor formation was prevented at a statistically significant level by immunization with any of the above-mentioned infected cells. The immunization was effective even with abortively infected cells (HaE; MoE) or with cells infected in the presence of 5-fluorodeoxyuridine. The induced immunity was Ad 12-specific, since neither cells infected with Ad2, Ad7 or Ad18 nor CV-1 cells infected with SV40 were able to prevent tumor formation. The most plausible explanation to these findings could be that Ad 12-specific tumor-specific transplantation antigen is induced on the surface of freshly virus-infected cells and it is responsible for induction of specific cellular immunity. This gives an experimental support to our hypothesis on the mechanism of induction of cellular immunity against virus infections and to the hypothesis proposed by Habel and by Sjogren to explain the immunoresistance against tumor cells induced following viral immunization.

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Using a method for labeling RNA with heavy nucleoside 5'-triphosphates, it was observed that the large particulate fraction isolated from reovirus-infected cells mediated iv vitro the synthesis of the three size classes of reovirus double-stranded RNA segments by elongating and terminating minus strand RNA whose synthesis had been initiated in the infected cells. The results are consistent with the hypothesis that each segment of reovirus plus strand template has an individual initiation site for the synthesis of minus strand RNA.

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