Cryptococcus neoformans is responsible for pulmonary and meningal infections in HIV patients. The lack of effective cellular cooperation caused by the low level of CD4+ cells, and the resistance of C. neoformans to phagocytosis allows growth and persistence of the yeast in the host. We describe here an in-vitro model of intracellular replication of C. neoformans inside J774-A.1 macrophages, and the determination of the intracellular antifungal activity of amphotericin B and fluconazole alone or in association with IFN-gamma. The maximum inhibitory effect was observed with one MIC of amphotericin B and 100 or 1000 IU/mL of IFN-gamma. amphotericin B alone (at 1 x MIC), or either 1 x or 50 x MIC of fluconazole in normal or IFN-gamma activated macrophages, did not eradicate the ingested yeast. A potential underlying mechanism of the synergy of amphotericin B in IFN-gamma primed macrophages was investigated by measurement of nitrite level and by use of the NO synthase competitive inhibitor, NG-monomethyl L-arginine (NMMA). One MIC of amphotericin B was able to activate the synthesis of nitrogen reactive intermediates in IFN gamma-primed macrophages. NMMA treated infected macrophages responded less well to IFN-gamma priming, resulting in a moderate inhibition in subsequent amphotericin B exposure.

In an attempt to produce Hog Cholera virus (HCV) preparations of high titre, optimal growth and trypsinization conditions of PK-15 microcarrier cell cultures were defined. Infecting a PK-15 Cytodex 3 microcarrier culture with HCV increased the yield of virus more than 10 times compared with conventional monolayer culture in Roux flasks.

A comparison was made on the properties of the inclusion body proteins of two insect viruses: the nucleopolyhedrosis viruses of the European pine sawfly, Neodiprion sertifer, Geoffroy, and the gypsy moth, Lymantria dispar, Linnaeus. The inclusion body proteins were characterized by the following parameters: amino acid composition, polyacrylamide gel electrophoresis in the absence and presence of sodium dodecyl sulfate--mercaptoethanol, isoelectric focusing, and alkaline protease activity. The properties of the inclusion body proteins of the two viruses were similar in many respects, but clear differences were observed. A principal difference was the absence of alkaline protease activity associated with the inclusion body proteins of N. sertifer nucleopolyhedrosis virus.

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