Polyspecific malaria antibodies present at the time of infection inhibit the development of immunity to malaria but antibodies specific for the malaria merozoite surface protein, MSP1, facilitate immunity

Serum taken from mice immune to malaria as a result of infection and drug cure, or from mice immunized with a recombinant form of the merozoite surface protein, MSP1, can provide passive protection of recipient mice against the lethal parasite, Plasmodium yoelii YM. However, recipients of MSP1-immune serum go on to develop long-term immunity, whereas recipients of serum from mice naturally immune to malaria rapidly lose their resistance to infection. We demonstrate that 'infection/cure' serum suppresses the development of both antibody and cell-mediated parasite-specific responses in recipients, whereas these develop in recipients of MSP1-specific antibodies. These data have profound implications for our understanding of the development of malaria immunity in babies who passively acquire antibodies from their mothers.

Carpogenic germination of Sclerotinia minor and potential distribution in Australia

This study confirms that Australian isolates of Sclerotinia minor can produce fertile apothecia and further demonstrates that ascospores collected from these apothecia are pathogenic to sunflower (Helianthus annuus). Sunflower is a known host of the related fungus Sclerotinia sclerotiorum and is grown in some regions where S. minor is known to occur. Head rot symptoms were produced following inoculation with S. minor ascospores. Predictive modeling using CLIMEX software suggested that conditions suitable for carpogenic germination of S. minor probably occur in Australia particularly in southern regions. Carpogenic germination is probably a rare event in northern regions and, if it does occur, probably does not coincide with anthesis in sunflower crops, therefore allowing disease escape.

Identification and minisequencing-based discrimination of SHV beta-lactamases in nosocomial infection-associated Klebsiella pneumoniae in Brisbane, Australia

Extended-spectrum beta-lactamases (ESBLs) are active against oxyimino cephalosporins and monobactams. Twenty-one Klebsiella pneumoniae isolates obtained between 1991 and 1995 at the Princess Alexandra Hospital in Brisbane, Australia, were subject to amplification and sequencing of the SHV beta-lactamase-encoding genes. Thirteen strains were phenotypically ESBL positive. Of these, six strains carried the bla(SHV-2a) gene and seven strains carried the bla(SHV-12) gene. Eight strains were phenotypically ESBL negative. Of these, seven strains carried the non-ESBL bla(SHV-11) gene and one strain carried the non-ESBL bla(SHV-1) gene. There was complete correspondence between the ESBL phenotype and the presence or absence of an ESBL-encoding gene(s). In addition, it was determined that of the 13 ESBL-positive strains, at least 4 carried copies of a non-ESBL-encoding gene in addition to the bla(SHV-2a) or bla(SHV12) gene. A minisequencing-based assay was developed to discriminate the different SHV classes. This technique, termed first-nucleotide change, involves the identification of the base added to a primer in a single-nucleotide extension reaction. The assay targeted polymorphisms at the first bases of codons 238 and 240 and reliably discriminated ESBL-positive strains from ESBL-negative strains and also distinguished strains carrying bla(SHV-2a) from strains carrying bla(SHV-12). In addition, this method was used to demonstrated an association between the relative copy numbers of bla(SHV) genes in individual strains and the levels of antibiotic resistance.

Dietary supplementation with vitamin E modulates avian intestinal immunity

The effect of dietary vitamin E on immunoglobulin A (IgA) antibody production, which acts as the first line of defence at the intestinal mucosa, has not been evaluated in chickens. In the present study the impact of the inclusion of supplementary levels of vitamin E to the diet, on total and antigen-specific IgA antibody titres, T-cell subsets and Ia+ cells, was assessed. From hatching, chickens received a maize-based diet which was supplemented with either 25, 250, 2500 or 5000 mg dl-alpha-tocopherol acetate/kg. Primary immunisation with tetanus toxoid (T. toxoid) emulsified in a vegetable oil-in-water adjuvant was administered by the intraperitoneal route at 21 d of age. At 35 d of age all birds received an oral booster vaccination of T. toxoid. Significantly higher total IgA antibody titres were present in the day 42 intestinal scrapings of birds receiving the 5000 mg/kg vitamin E-supplemented diet (VESD) (P=0.05) and a notable increase was observed in birds receiving the 250 mg/kg VESD (P=0.06). At days 21 and 42 total serum IgA antibody titres of birds receiving the 250 mg/kg VESD was significantly higher (P

Post-discharge surveillance: can patients reliably diagnose surgical wound infections?

Post-discharge surgical wound infection surveillance is an important part of many infection control programs. It is frequently undertaken by patient self-assessment, prompted either by a telephone or postal questionnaire. To assess the reliability of this method, 290 patients were followed for six weeks post-operatively. Their wounds were photographed and also covertly assessed for signs of infection by two experienced infection control nurses (ICNs). Patients also responded to a postal questionnaire seeking evidence of infection at both week four and week six post-surgery. Correlation between the patient's assessment of their wound and the ICNs diagnosis was poor (r = 0. 37) with a low positive predictive value (28.7%), although negative predictive value was high (98.2%). Assessment of photos for signs of infection by two experienced clinicians also correlated poorly with the ICNs diagnosis of infection (r = 0.54). The patient's recall of prescription of an antibiotic by their general practitioner (GP) for wound infection during the postoperative period correlated best with the ICNs diagnosis (r = 0.76). This latter measure, particularly when confirmed by the GP in those patients reporting an infection, appears to provide the most valid and resource efficient marker of post-discharge surgical wound infection.

Parenteral and mucosal delivery of a novel multi-epitope M protein-based group A streptococcal vaccine construct: investigation of immunogenicity in mice

Primary vaccine strategies against group A streptococci (GAS) have focused on the M protein-the target of opsonic antibodies important for protective immunity. We have previously reported protection of mice against GAS infection following parenteral delivery of a multi-epitope vaccine construct, referred to as a heteropolymer. This current report has assessed mucosal (intranasal (i.n.) and oral) delivery of the heteropolymer in mice with regard to the induction and specificity of mucosal and systemic antibody responses, and compared this to parenteral delivery. GAS-specific IgA responses were detected in saliva and gut upon i.n. and oral delivery of the heteropolymer co-administered with cholera toxin B subunit, respectively. High titre serum IgG responses were elicited to the heteropolymer following all routes of delivery when administered with adjuvant. Moreover, as with parenteral delivery, serum IgG antibodies were detected to the individual heteropolymer peptides following i.n. but not oral delivery. These data support the potential of the i.n. route in the mucosal delivery of a GAS vaccine. (C) 2002 Elsevier Science Ltd. All rights reserved.

Inhibitors of COP-mediated Transport and Cholera Toxin Action Inhibit Simian Virus 40 Infection

Simian virus 40 (SV40) is a nonenveloped virus that has been shown to pass from surface caveolae to the endoplasmic reticulum in an apparently novel infectious entry pathway. We now show that the initial entry step is blocked by brefeldin A and by incubation at 20degreesC. Subsequent to the entry step, the virus reaches a domain of the rough endoplasmic reticulum by an unknown pathway. This intracellular trafficking pathway is also brefeldin A sensitive. Infection is strongly inhibited by expression of GTP-restricted ADP-ribosylation factor 1 (Arf1) and Sar1 mutants and by microinjection of antibodies to betaCOP. In addition, we demonstrate a potent inhibition of SV40 infection by the dipeptide N-benzoyl-oxycarbonyl-Gly-Phe-amide, which also inhibits late events in cholera toxin action. Our results identify novel inhibitors of SV40 infection and show that SV40 requires COPI- and COPII-dependent transport steps for successful infection.

Osteonectin/SPARC induction by ectopic beta(3) integrin in human radial growth phase primary melanoma cells

Expression of the beta(3) integrin subunit in melanoma in situ has been found to correlate with tumor thickness, the ability to invade and metastasize, and poor prognosis. Transition from the radial growth phase (RGP) to the vertical growth phase (VGP) is a critical step in melanoma progression and survival and is distinguished by the expression of beta(3), integrin. The molecular pathways that operate in melanoma cells associated with invasion and metastasis were examined by ectopic induction of the beta(3), integrin subunit in RGP SBcl2 and WM1552C melanoma cells, which converts these cells to a VGP phenotype. We used cDNA representational difference analysis subtractive hybridization between beta(3)-Positive and -negative melanoma cells to assess gene expression profile changes accompanying RGP to VGP transition. Fourteen fragments from known genes including osteonectin (also known as SPARC and BM-40) were identified after three rounds of representational difference analysis. Induction of osteonectin was confirmed by Northern and Western blot analysis and immunohistochemistry and correlated in organotypic cultures with the beta(3)-induced progression from RGP to VGP melanoma. Expression of osteonectin was also associated with reduced adhesion to vitronectin, but not to fibronectin. Osteonectin expression was not blocked when melanoma cells were cultured with anti-alpha(v)beta(3) LM609 mAb, mitogen-activated protein kinase, or protein kinase C inhibitors, indicating that other signaling pathway(s) operate through a(v)beta(3) integrin during conversion from RGP to VGP.

Identification of T cell epitopes on the 33-kDa fragment of Plasmodium yoelii merozoite surface protein 1 and their antibody-independent protective role in immunity to blood stage malarial

Merozoite surface protein 1 (MSP1) of malaria parasites undergoes proteolytic processing at least twice before invasion into a new RBC. The 42-kDa fragment, a product of primary processing, is cleaved by proteolytic enzymes giving rise to MSP1(33), which is shed from the merozoite surface, and MSP1(19), which is the only fragment carried into a new RBC. In this study, we have identified T cell epitopes on MSP1(33) of Plasmodium yoelii and have examined their function in immunity to blood stage malaria. Peptides 20 aa in length, spanning the length of MSP1(33) and overlapping each other by 10 aa, were analyzed for their ability to induce T cell proliferation in immunized BALB/c and C57BL/6 mice. Multiple epitopes were recognized by these two strains of mice. Effector functions of the dominant epitopes were then investigated. Peptides Cm15 and Cm21 were of particular interest as they were able to induce effector T cells capable of delaying growth of lethal P. yoelii YM following adoptive transfer into immuno-deficient mice without inducing detectable Ab responses. Homologs of these epitopes could be candidates for inclusion in a subunit vaccine.

Enhancement or modulation of the vector competence of ochlerotatus vigilax (Diptera : Culicidae) for Ross River virus by temperature

Two different doses of Ross River virus (1111) were fed to Ochlerotatus vigilax (Skuse), the primary coastal vector in Australia; and blood engorged females were held at different temperatures up to 35 d. After ingesting 10(4.3) CCID50/Mosquito, mosquitoes reared at 18 and 25degreesC (and held at the same temperature) had higher body remnant and head and salivary gland titers than those held at 32degreesC, although infection rates were comparable. At 18, 25, and 32degreesC, respectively, virus was first detected in the salivary glands on days 3, 2, and 3. Based on a previously demonstrated 98.7% concordance between salivary gland infection and transmission, the extrinsic incubation periods were estimated as 5, 4, and 3 d, respectively, for these three temperatures. When Oc. vigilax reared at 18, 25, or 32degreesC were fed a lower dosage of 10(3.3) CCID50 RR/mosquito, and assayed after 7 d extrinsic incubation at these (or combinations of these) temperatures, infection rates and titers were similar. However, by 14 d, infection rates and titers of those reared and held at 18 and 32degreesC were significantly higher and lower, respectively. However, this process was reversible when the moderate 25degreesC was involved, and intermediate infection rates and titers resulted. These data indicate that for the strains of RR and Oc. vigilax used, rearing temperature is unimportant to vector competence in the field, and that ambient temperature variations will modulate or enhance detectable infection rates only after 7 d: extrinsic incubation. Because of the short duration of extrinsic incubation, however, this will do little to influence RR epidemiology, because by this time some Oc. vigilax could be seeking their third blood meal, the latter two being infectious.

Epidemiological significance of subterranean Aedes aegypti (Diptera : Culicidae) breeding sites to dengue virus infection in charters towers, 1993

The objective of this study was to determine the epidemiological significance of subterranean mosquito breeding sites to the 1993 outbreak of dengue fever (type 2) in the northern Queensland town of Charters Towers, Australia. In recent studies on subterranean mosquito breeding, containers such as wells and service manholes have been shown to be important breeding sites to Australia's only dengue vector, Aedes aegypti (L.). This study demonstrates a direct epidemiological association between subterranean breeding sites and dengue virus infection. The mean distance between residents seropositive for dengue 2 and the nearest subterranean container (113 m) was significantly less than for a randomly selected control (191 m), (F = 81.9; df = 1, 478; P < 0.001). Residents positive for dengue 2 antibodies was 2.47 (95% confidence interval 1.88-3.24) times higher for those living within 160 m of a well or service manhole, compared with those residing further away. These findings emphasize the importance of including subterranean water containers in Ae. aegypti surveillance and control programs.

Immune correlate study on human Schistosoma japonicum in a well-defined population in Leyte, Philippines: I. Assessment of 'resistance' versus 'susceptibility' to S-japonicum infection

This study describes the categorical classification of 155 individuals living in an endemic village in Macanip, Leyte, Philippines as 'resistant' or 'susceptible' to Schistosoma japonicum infection using available exposure, infection and reinfection data collected from a 3-year water contact (WC) study. Epidemiological parameters including age, sex, and infection intensities in relation to observed reinfection patterns are also described. This classification was used in subsequent immunological studies described in two accompanying papers to identify protective immune mechanisms among resistant individuals induced by defined candidate vaccine molecules for S. japonicum. The study suggests that individuals who were most vulnerable to rapid reinfection were children belonging to the 5-14 age group. A drop in incidence at age group 15-19 and decreased intensity of infection starting at this age group and older (15+) suggests development of immunity. Controlling for the effect of the other variables, a multivariate analysis showed significant association for sex, in that females were more likely to be resistant. This implies that other than acquired immunity to infection, some age-dependent host factors may also play an important role in the overall changes of reinfection patterns seen in schistosomiasis japonica in this population. Crown Copyright (C) 2002 Published by Elsevier Science B.V. All rights reserved.