No abstract

Eighteen Rhesus monkeys were immunized with a fresh or lyophilized antigen preparation obtained from erythrocytes infected with Plasmodium knowlesi. Sixteen of these monkeys showed a positive delayed hypersensitivity response when subsequently skin tested with the immunizing antigen. Ten of the 16 positive reactors survived a P, knowlesi challenge, the remaining 6 showed several indications of protection. None of the 18 control monkeys gave a positive skin reaction or survived the challenging inoculum. Macro- and microscopical evidence suggests that the dermal reaction is of a delayed type. Preliminary biochemical analysis of the antigen used in this experiment is included and its significance is discussed. Hematological data is also presented.

Studies carried out on four rhesus monkeys (Macaca mulatta) that had been vaccinated against Plasmodium knowlesi show that the immunized animals were protected against a challenge with a heterologous strain of P. knowlesi. This protection was shown to be present even 4 years after the immunization schedule has been completed. The effect could not be attributed toprevious infections with the parasite, since four control rhesus monkeys that had recovered from one to four challenges with P. knowlesi died when exposed to the heterologous strain. Data obtained from the lymphocyte transformation test and the radioimmunoassay are also presented.

As higher density formats become more and more common in HTS labs, the expectations for maintaining faster, lower cost screens puts great pressure on traditional 96-well screens. In some cases higher density formats are not compatible with the assay. This seems especially true in cell-based assays. In our case, the nature of the cells' response forced us to remain in 96-well plates. In this paper, we describe the development of a luminescence reporter assay and its performance in two detection modes, flash and glow. The advantages in cost and throughput for each technique are explored, along with automation considerations. An additional new technology, the use of pins for low-volume transfers, is also briefly described because of its dramatic effect on our screen's throughput. However, it will be more thoroughly presented in a future publication. Comparing the technologies available for HTS aids in designing automated systems that meet the unique needs of each assay.

SYNOPSIS. The ability to protect rats against Plasmodium berghei by the transfer of spleen cells by various routes of injection was examined. Intraperitoneal and intravenous injections of cells taken from spleens of recovered rats transferred immunity. Intramuscular injection of the same material was unsuccessful. All injections were derived from the same pool of immune spleen cells and contained equal numbers of trypan blue‐excluding cells.