Effect of bioamines on uptake of promastigotes of Leishmania donovani by hamster peritoneal macrophages.

Epinephrine and norepinephrine inhibit attachment of Leishmania donovani promastigotes to cultured hamster peritoneal macrophages. The inhibition was significant at catecholamine concentrations of 10(-4) and 10(-5) M and occurred when they were added to the cell mixtures, or after pre-treatment of either macrophages or parasites. Inhibition of attachment after pre-treatment was less marked than when the catecholamines were added to parasite-cell mixtures. Similar results were obtained with dibutyryl cyclic AMP, cholera toxin, theophylline, and cadaverine which raise intracellular cyclic AMP (cAMP). Pretreatment of parasites or macrophages with the bioamines elevated the intracellular cAMP concentration. It is suggested that the inhibitory effect on the host-parasite interaction is mediated through cAMP.

Effects of amino acids on colony phenotype of Neisseria gonorrhoeae.

The effects of amino acid supplementation of commercially available semidefined GC media (Oxoid GC medium and Difco GC base) on the stability of the virulent colony phenotype of Neisseria gonorrhoeae were studied. The -SH-containing amino acids, together with glycine, were found to cause segregation of avirulent colony types followed by growth inhibition after addition of 40 mg/100 ml. Proline and arginine were found to change the colony phenotype profile significantly without reducing the viable count. Arginine supplementation in both media caused a progressive loss of virulent colony types, whereas proline had the opposite effect.

Phage-induced change of toxigenesis in Vibrio cholerae.

A temperate phage coding for constitutive hypertoxigenicity has been constructed in Vibrio cholerae strain 569B and used to lysogenise the low-toxin-producing strain MAK 757; 18% of lysogens showed 10-100-fold increase in toxin production. This property was also transmitted at low frequency to second generation lysogens. Thus temperate phage can increase toxin production in a low-toxin-producing strain.

Mutagenic action of phaseolinone, a mycotoxin isolated from Macrophomina phaseolina.

Phaseolinone was mutagenic to excision-repair-deficient strains of Escherichia coli WP2 and also to Salmonella typhimurium TA 100. The repair test was indicative of covalent binding of the toxin to DNA. The side-chain epoxide and the hydroxy groups of the molecule were found to be essential for mutagenic activity.

Leishmania donovani: amastigote inhibition and mode of action of berberine.

Berberine, an alkaloid from Berberis aristata Linnaeus, may be a useful drug for the treatment of visceral leishmaniasis. In both the 8-day and long-term models of Leishmania donovani infection in hamsters, it markedly diminished the parasitic load and proved to be less toxic than pentamidine. It rapidly improved the hematological picture of infected animals. Like pentamidine, it inhibited in vitro multiplication of amastigotes in macrophage culture and their transformation to promastigotes in cell free culture. Manometric studies showed that both drugs had inhibitory action on both the endogenous and the glucose-stimulated respiration of amastigotes. They inhibited incorporation of [14C]adenine, [14C]uracil, and [3H]thymidine into nucleic acids, and of [14C]leucine into the protein of amastigotes, indicating an inhibitory action on macromolecular biosynthesis. They also decreased deoxyglucose uptake. Using spectrophotometric, spectrofluorimetric, and circular dichroism techniques, berberine was found to interact in vitro with nuclear DNA from L. donovani promastigotes.

The systematic serology of Neisseria gonorrhoeae: antigens associated with pathogenesis in Neisseria spp. from man.

Sonicates of eight Neisseria species from man were analysed in a micro-Ouchterlony double-diffusion absorption assay in comparison with a gonococcal reference antiserum-antigen system. Five major gonococcal precipitin zones were identified which comprised genus-, species- and type-specific components. One antigen was found in all strains of three species with pathogenic capability--N. gonorrhoeae, N. meningitidis and N. flavescens. It was not detected in N. lactamica, N. pharyngis, N. elongata, N. cinerea or N. catarrhalis.

Phage beta interaction with Vibrio cholerae.

The role of temperate phage beta in determining the serology and eltor-lytic phage sensitivity in Vibrio cholerae was investigated. The only serological change found in six host strains was a change to roughness. This was accompanied by failure to adsorb several of the lytic phages. Various phage-sensitivity changes were induced by phage beta in two hosts at the post-adsorption level. In strain HP47, three types of progeny were obtained of which one was universally resistant to lytic phages. These untypable lysogens were culturally stable but gave rise to segregants of the rare phage-type 6 on single colony selection.

Role of temperate phage in determining lytic phage sensitivity and serotype of Vibrio cholerae.

The effect of lysogenization with five temperate phages from various sources on serotype and lytic phage sensitivity was investigated in six cultures of Vibrio cholerae of both classical and El Tor biotypes. No changes in serotype or in classical phage sensitivity in the classical biotype were observed. Four of the temperate phages were homoimmune and induced resistance to one of the El Tor typing phages, E3, thereby causing a type change in El Tor strains. The sensitivity to the other phages was not changed. In 14 natural isolates too, E3 (group III) phage resistance correlated with the presence of temperate phage. Postadsorption exclusion was found to be the mechanism of resistance involved. The fifth phage, VcA-1, had a unique immunity profile. It could infect the El Tor biotype of V. cholerae but caused no change in the host properties investigated.

Evaluation of the phenol-induced flagellar agglutination test for the identification of the cholera group of vibrios.

Applied routinely to 1081 recently isolated cultures, the phenol-induced slide-agglutination test (standard procedure) with flagellar antiserum corrently identified 98.9% of Vibrio cholerae strains of O type-I and NAG serotypes; 1.0% of cultures were unstable in phenol-saline. The incidence of instability and other types of defect was higher (7.3%) in older stock cultures. The majority of such strains were successfully tested by one of the three modified procedures. No cross-reactions were observed in 47 cultures of other species including the halophilic vibrios. Only one out of the 1205 cultures of V. cholerae tested by all procedures reacted negatively; this strain was found to lack functional flagella. These results establish the significance of flagellar specificity as a classificatory determinant in V. cholerae, and the fidelity and utility of the phenol test in routine bacteriology.

The agglutination reactions of cholera vibrios.

The present study with 11 strains of vibrio using single-dose and hyperimmune antisera confirmed earlier observations on the cross-reactivity of the flagellar (H) agglutinating antigens of cholera and NAG vibrios. The effect of several variables on the agglutinating sensitivity of cell suspensions was determined by measuring the reaction rate in the presence of constant O- or H-antibody. The variables investigated were culture conditions, antigen dilution, reaction temperature, formalin fixation and heat-treatment; all were found to affect cholera and NAG serovars similarly. The optimal conditions for the O- and H-tests were markedly different. Dilute, young living broth cultures were highly sensitive to O- but not H-antibody. Conditions favoring the H-reaction were 48-hr culture on firm dry agar, high suspension opacity, a reaction temperature of 45 C and formalin fixation. The inverse relationship of O- and H-sensitivity under these conditions indicated that the flagellar antigen in the growing vibrio is masked by an O-sensitive layer. The temperature of denaturation of the unfixed H-antigen before or after reaction with antiserum was 64 +/- 0.5 C and could be used as a criterion of the H-reaction.

Vibrio cholerae flagellar antigens: a serodiagnostic test, functional implications of H-reactivity and taxonomic importance of cross-reactions within the Vibrio genus.

Serodiagnostic tests for all serotypes of Vibrio cholerae using H-antisera were investigated. Activity motile cell lines of 155 stock and international reference cultures of human, animal, fish, and halophilic Vibrios, Aeromonas, Comomonas, Pseudomonas, Salmonella, and Escherichia were investigated. Without exception, all cholera vibrios (including the NAG serotypes) reacted with H sera. Positive reactions were obtained specifically (a) within 2 hrs at 52 degrees C in the tube test using thick formalized suspensions and H antisera at optimal proportion titre and (b) within 30 sec by slide agglutination of fresh cultures. The other vibrios investigated reacted similarly with their homologous H antisera. 2. The rapid diagnostic techniques of fluorescent antibody labeling or immobilization were unsuccessful, V. cholerae flagella being refractive to H sera in these tests. V. cholerae was, however, sensitive in a type-specific manner to O antisera. These and related observations suggest that O antigen has a functional role in Vibrio motility. 3. Interspecies H cross-reactions between V. cholerae and fish and animal vibrios which correlated with bacteriologic similarity, were demonstrated. O antigens of these vibrios were strain specific. Cross-absorption analysis indicated that the H antigens of vibrios were characteristic and homogenous within the species, and therefore a potentially important taxonomic criterion of Vibrio species.