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Porphyromonas gingivalis strain W50 was grown under haemin-limitation and haemin-excess conditions in a chemostat at pH 7.5. The maximum specific growth rate (mumax) was determined at both haemin concentrations (mumax = 0.236 +/- 0.052 and 0.271 +/- 0.039 h-1, respectively). This enabled dilution rates to be adjusted so that the virulence and enzyme activity of haemin-limited and haemin-replete cells could be compared at identical relative growth rates (murel) of 0.25, 0.50 and 0.75 of their respective mumax. The data showed that the fastest growing cells were significantly more virulent than those grown more slowly, irrespective of haemin concentration. However, at each growth rate tested, cells grown under haemin-excess conditions were always more virulent than haemin-limited cells. Trypsin-like enzyme activity of whole cultures was also greater at each growth rate under haemin-excess conditions while, conversely, collagenolytic activity was generally higher in haemin-limited cultures. Thus, although growth rate had an effect on the virulence and enzyme activity of P. gingivalis, the availability of haemin for growth was the most significant factor.

A monoclonal antibody CWE4 was produced against the 60-kilodalton (kDa) antigen of Candida albicans . Previously we demonstrated that antibody to this antigen was the second most commonly produced in patients with systemic candidiasis. Immunoelectron microscopy demonstrated reactivity of CWE4 with a nuclear component in yeast and mycelial cells. It was a high affinity IgG immunoglobulin. CWE4 was incorporated in a dot immunobinding assay to detect circulating 60 kDa antigen in sera from patients with systemic candidiasis. It was much more sensitive than reverse passive latex agglutination (RPLA), being positive in 69% of neutropenic patients and 80% of non-neutropenic patients, compared to 33% and 68% respectively with RPLA. False positives were rare among uninfected controls but common among superficially infected and colonized patients. In a mouse model of candidal peritonitis, CWE4 compared unfavourably with a rabbit hyperimmune candidal antiserum in its ability to reduce the severity of infection.

The susceptibility of common marmosets and cotton-top tamarins to infection by HIV-2 in vivo was tested. One year and 19 months, respectively, post-inoculation, sera taken from three of four animals from each species are reactive for HIV-2 antibodies and HIV-specific nucleotide sequences were demonstrated in short-term cultures of PBL from two cotton-top tamarins. The animals remain in good health.