Differentiation of innate but not learnt responses to host‐habitat odours contributes to rapid host finding in a parasitoid genotype

Abstract In parasitoids, host‐habitat odour can influence host searching within the habitat. This is the case in Leptopilina sp. (Hymenoptera, Figitidae), a Drosophila parasitoid searching for larvae by ovipositor probes. This a behaviour can be conditioned to fruit odours. In a previous study, the latency of probing to a fruit odour is reported to have a genetic variability within a laboratory strain. This suggests a link between rapidity of host discovery and fitness. In the present study, this hypothesis is tested by comparing responses to host‐habitat odours between two genotypes of Leptopilina heterotoma Thomson, from the Mediterranean coast (Antibes) and from Burgundy (Tailly). The two genotypes present contrasting rhythms and levels of locomotor activity linked to contrasting interspecific competition in their area of origin. The high activity observed in the Mediterranean genotype is interpreted as an adaptive response to a limited time‐window to win against a competitor species absent in Burgundy. The present study finds differentiation in innate but not learnt responses to host‐habitat odours. The more active genotype (Antibes) has a higher probability and a shorter latency of innate probing to the odours than the less active genotype (Tailly); Antibes females also find larvae and complete infestations more rapidly. Learning equalizes the probability and the latency of probing to the odours in both strains, and increases the probing duration. Innate responses to host‐habitat odours would allow time‐limited insects to increase their reproductive rate, when host predictability is high in the habitat. Selection of faster innate responses to host and habitat cues without evolution of learnt responses indicates that the initial host discovery is more crucial to fitness than subsequent ones.     

Duplication of primate and rodent B7-H3 immunoglobulin V- and C-like domains: divergent history of functional redundancy and exon loss

B7-H3 is a novel protein structurally related to the B7 family of ligands by the presence of a single set of immunoglobulin-V-like and immunoglobulin-C-like (VC) domains. By multiplex PCR, the dominantly expressed form of human B7-H3 was found to be a splice variant containing tandemly duplicated VC domains (VCVC). In contrast, mouse B7-H3 cDNA contained only one single VC form due to an exon structure corresponding to V-(pseudoexon C)-(pseudoexon V)-C. Comparisons of human, monkey, mouse, and hamster genomic B7-H3 reveal that primates, but not rodents, exhibited a higher degree of intramolecular sequence similarity between VC duplications than between molecules. Both VC and VCVC forms of human B7-H3 inhibited CD4(+) T cell proliferation and downregulated cytokine production upon TCR activation. These results suggest independent, but convergent, paths of B7-H3 active domain duplication followed by divergent histories of exon degeneration in rodents and exon maintenance by humans.     

Efficacy of common laboratory disinfectants on the infectivity of Cryptosporidium parvum oocysts in cell culture

Nine liquid disinfectants were tested for their ability to reduce infectivity of Cryptosporidium parvum oocysts in cell culture. A 4-min exposure to 6% hydrogen peroxide and a 13-min exposure to ammonium hydroxide-amended windshield washer fluid reduced infectivity 1,000-fold. Other disinfectants tested (70% ethanol, 37% methanol, 6% sodium hypochlorite, 70% isopropanol, and three commercial disinfectants) did not reduce the infectivity after a 33-min exposure. The results indicate that hydrogen peroxide and windshield washer fluid or ammonium hydroxide disinfectant may be suitable laboratory disinfectants against C. parvum oocysts.     

Proteomic and immunoproteomic characterization of a DIVA subunit vaccine against <Emphasis Type="Italic">Actinobacillus pleuropneumoniae</Emphasis>

Background  

Protection of pigs by vaccination against Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is hampered by the presence of 15 different serotypes. A DIVA subunit vaccine comprised of detergent-released proteins from A. pleuropneumoniae serotypes 1, 2 and 5 has been developed and shown to protect pigs from clinical symptoms upon homologous and heterologous challenge. This vaccine has not been characterized in-depth so far. Thus we performed i) mass spectrometry in order to identify the exact protein content of the vaccine and ii) cross-serotype 2-D immunoblotting in order to discover cross-reactive antigens. By these approaches we expected to gain results enabling us to argue about the reasons for the efficacy of the analyzed vaccine.     

Identification of an interleukin 17F/17A heterodimer in activated human CD4+ T cells

IL-17F and IL-17A are members of the IL-17 pro-inflammatory cytokine family. IL-17A has been implicated in the pathogenesis of autoimmune diseases. IL-17F is a disulfide-linked dimer that contains a cysteine-knot motif. We hypothesized that IL-17F and IL-17A could form a heterodimer due to their sequence homology and overlapping pattern of expression. We evaluated the structure of recombinant IL-17F and IL-17A proteins, as well as that of natural IL-17F and IL-17A derived from activated human CD4+ T cells, by enzyme-linked immunosorbent assay, immunoprecipitation followed by Western blotting, and mass spectrometry. We find that both IL-17F and IL-17A can form both homodimeric and heterodimeric proteins when expressed in a recombinant system, and that all forms of the recombinant proteins have in vitro functional activity. Furthermore, we find that in addition to the homodimers of IL-17F and IL-17A, activated human CD4+ T cells also produce the IL-17F/IL-17A heterodimer. These data suggest that the IL-17F/IL-17A heterodimer may contribute to the T cell-mediated immune responses.     

Discovery of an undescribed protostrongylid nematode from the endangered pampas deer (Ozotoceros bezoarticus celer) in Argentina

Dorsal-spined protostrongylid nematode larvae (Metastrongyloidea: Protostrongylidae) were recovered from the feces of the endangered pampas deer (Ozotocerus bezoarticus celer) in Campos del Tuyú Wildlife Reserve, Bahia Samborombón, Argentina. Partial DNA sequences from the large subunit ribosomal RNA (LSU rRNA) gene and from the second internal transcribed spacer region (ITS2) were amplified, cloned, sequenced, and compared to those of other nematodes. Nucleotide alignment and phylogenetic analysis of the sequences indicate that this protostrongylid nematode is most closely related to Parelaphostrongylus spp. as inferred from the LSU rRNA sequence analysis. Analysis of the ITS2 spacer indicated that the pampas deer protostrongylid is nested in a clade containing Parelaphostrongylus and Elaphostrongylus spp. These sequences differed considerably from those of other protostrongylid nematodes, and were most similar to those of Parelaphostrongylus spp. and Elaphostrongylus spp. in spite of clear variability from both genera. These results suggest that the protostrongylid from pampas deer is an undescribed nematode that likely belongs in the subfamily Elaphostrongylinae.     

Phenotypic and genotypic characterization of Cryptosporidium species and isolates

Recent outbreaks of cryptosporidiosis from contaminated water supplies have led to a need for the detection of Cryptosporidium oocysts from various hosts and contaminating sources. The presence of nonpathogenic species or strains of Cryptosporidium is important for diagnostic purposes as there is a potential for false-positive detection of pathogenic parasites. The present review focuses on phenotypic differences and recent advances in genotypic analyses of the genus Cryptosporidium with an emphasis on detecting various isolates and identifying differences in Cryptosporidium parvum and other species in this genus. The information currently available demonstrates important patterns in DNA sequences of Cryptosporidium, and our understanding of macro- and microevolutionary patterns has increased in recent years. However, current knowledge of Cryptosporidium genetic diversity is far from complete, and the large amount of both phenotypic and genotypic data has led to problems in our understanding of the systematics of this genus. Journal of Industrial Microbiology & Biotechnology (2001) 26, 95–106. Received 18 March 2000/ Accepted in revised form 13 August 2000     

Binding of LFA-1 (CD11a) to Intercellular Adhesion Molecule 3 (ICAM-3; CD50) and ICAM-2 (CD102) Triggers Transmigration of Human Immunodeficiency Virus Type 1-Infected Monocytes through Mucosal Epithelial Cells

Transmigration of human immunodeficiency virus (HIV)-infected mononuclear cells through the genital mucosa is one of the possible mechanisms of sexual transmission of HIV. Here, we investigated the transmigration of cell-associated R5-tropic HIV type 1 (HIV-1) through a tight monolayer of human epithelial cells in vitro. We show that this process is dependent on an initial interaction between alphaLbeta2 integrin CD11a/CD18 on infected monocytic cells and intercellular adhesion molecule 2 (ICAM-2; CD102) and ICAM-3 (CD50) on the apical membrane of epithelial cells. The CD50 and CD102 ligands were overexpressed on epithelial cells when the cells were activated by proinflammatory cytokines in the cellular microenvironment. An accumulation of proviral DNA was found in the transmigrated cells, clearly reflecting the preferential transepithelial migration of HIV-1-infected cells under proinflammatory conditions. Our observations provide new insights supporting the hypothesis that HIV-infected mononuclear cells contained in genital secretions from infected individuals may cross the epithelial genital mucosa of an exposed receptive sexual partner, particularly under inflammatory conditions of damaged genital tissue. Understanding the fundamental aspects of the initial HIV entry process during sexual transmission remains a critical step for preventing human infection and developing further vaccinal strategies and virucidal agents.