Late Breaker Abstracts
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Late Breaker Abstracts 2480 CLONING AND CHARACTERIZATION OF SCHISTOSOMA JAPONICUM INSULIN RECEPTORS: POTENTIAL NEW INTERVENTION TARGETS AGAINST SCHISTOSOMIASIS Hong You, Wenbao Zhang, Malcolm K. Jones, Geoffrey N. Gobert, Donald P. McManus Queensland Institute of Medical Research, Brisbane, Australia Adult schistosomes depend for growth and development on hormonal signals from the mammalian host, which may include the insulin signalling pathway. To determine the precise role of insulin receptors in schistosome biology, we isolated two types of insulin receptors from Schistosoma japonicum, S. japonicum insulin receptor 1 (SjIR1) and SjIR2, with features similar to insulin receptors from other taxa. The sequences share 70% and 74% sequence identity to S. mansoni insulin receptor 1 and 2 (SmIR1 and SmIR2), respectively. SjIR1 and SjIR2 are conserved in tyrosine kinase domain to the other IRs, such as humans, mouse and Drosophila melanogaster. Phylogenetic analysis showed that SjIR2 and SmIR2 are close to Echinococcus multilocularis insulin receptor (EmIR), which is only one insulin receptor isolated in the tapeworm, indicating that SjIR2, SmIR2 and EmIR may be orthologs sharing the similar roles in the both schistosomes and Echinococcus, while IR1 homolog in E. multilocularis would have been lost during the cestode evolution. Real time PCR showed that the SjIRs were differentially expressed in different stages of S. japonisum, mainly in the stages in mammalian host, suggesting SjIRs may be involved in the host-parasite crosstalk. Yeast two-hybrid and BIAcore analysis demonstrated that the SjIRs specifically bound human insulin both in vivo and in vitro. Immunolocalization analysis revealed that SjIR1 is located on the internal and external teguments of adult worms, whereas SjIR2 is located in the parenchyma of male and vitelline of female worm, suggesting that SjIR1 may be involved in utilizing host insulin from the environment and SjIR2 is likely involved in providing insulin to stimulate cell growth and differentiation, and also SjIR2 may play an important role in fecundity of female worm. Adult worms of S. japonicum possess insulin receptors that can specifically bind to insulin, indicating that the parasite can utilize host insulin for development and growth by sharing the same pathway as mammalian cells for controlling cell differentiation and proliferation. A complete understanding of the role of SjIRs in the biology of S. japonicum may result in their use as new targets for drug and vaccine development against schistosomiasis. 2483 A DNA vaccine trial using DBP, MSP-1, and AMA-1 of the reemerging Korean Plasmodium vivax isolates Jong-Yil Chai1, Hyo-Jin Kim1, Bong-Kwang Chung1, Jin-Ju Lee1, Kyoung-Ho Pyo1, Eun-Hee Shin2 1Department of Parasitology and Tropical Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea, 2Department of Parasitology and Tropical Medicine, Seoul National University College of Medicine, Seoul, and Seoul National University Bundang Hospital, Seongnam, Republic of Korea Studies on the reemerging Korean Plasmodium vivax malaria after 1993 have focused on identifying antigenic proteins and genotypes of isolates from patients. Recently, in order to evaluate the usefulness of DNA vaccine candidates using merozoite antigens, we cloned 3 major candidate antigens, i.e., DBP, MSP-1, and AMA-1. The DNA fragments of PCR products were subcloned into TA vectors and the genes encoding these antigens were sequenced. Then, the antigens were cloned into the pcDNA 3.1(-) vector, and expression plasmids were finally constructed. The vector was inserted with mutant ubiquitin genes, and thus the expression plasmids including each candidate antigen were expected to be generated by the ubiquitin-proteasome pathway in mammalian cells. COS-7 cells were transfected with the expression plasmids using lipofectamine, and the merozoite antigens were successfully expressed in cultured COS-7 cells. The molecular weight of AMA-1 appeared to be 56.8 kDa and that of DBP was 37.8 kDa. Our vectors containing the mutant ubiquitin may induce antigen presentation to MHC class I molecules. Mice were challenged by intramuscular injection with DNA vectors carrying 3 kinds of the DNA vaccine candidates. The results showed that inoculation of AMA-1-inserted pcDNA vector induced significant increases of IFN-γ mRNA signals and total IgG and IgG2a titers. Similarly, DBP- and MSP-1-inserted pcDNA vectors also induced increases of IFN-γ mRNA signals. In addition, we immunized mice using a gene gun carrying the target DNA. We could confirm a significant increase of CD8+-T cell population in the spleen as compared with controls immunized with pcDNA 3.1(-) vector alone. Our results suggest that DNA vectors carrying the DNA of the reemerging Korean P. vivax can induce strong immune responses in recipient mice. 2484 Patterns of valvular involvement in rheumatic heart disease Pramod Acharya, Sandip Basnet, Rupak Bhandari, Nikesh Raj Shrestha, Sanjib Kumar Sharma, Prahlad Karki B.P. Koirala Institute of Health Sciences, Dharan, Nepal Background: The incidence of acute rheumatic fever (ARF) is high in Nepal. Its sequel in the form of chronic rheumatic valvular heart disease is a major cause of mortality and morbidity among pediatric and adult populations. The aims of the study were to analyze patterns of valve involvement in the pediatric and adult age groups and their complications. Methods: The study was a retrospective case series analysis that included 1606 patients with chronic rheumatic valvular heart disease who presented to a tertiary care center in eastern Nepal over a period of 10 years. All of these patients underwent transthoracic echocardiography (TTE) by trained physicians. Results: Female to male ratio in the study population was 1.6: 1. The combined mitral and aortic valve lesions were the commonest pattern of rheumatic valve involvement seen in 51% of pediatric (age≤ 18 years) and 49% of adult (age >18 years) populations. It was followed by the involvement of mitral valve alone with a frequency of 44% and 47% in pediatric and adult populations respectively. Only 5% of pediatric and 4% of adult populations had aortic valve involvement as a single valve lesion. Rheumatic involvement of tricuspid and pulmonic valves was not observed in any of these cases. Pulmonary arterial hypertension was observed in 28% of pediatric age group and 40% adult age group. Echocardiographic evidence of infective endocarditis was seen in 6.5% (pediatric) and 5.9% (adult) patients. Left atrial (LA) clot was more common in adult population (2.8%) than in pediatric population (1.8%) as detected by TTE. Only 3 out of 1606 patients had undergone valve replacement surgery. Conclusion: The pattern of valve involvement in chronic RHD in Nepal doesn’t differ from other developing countries. The high frequencies of pulmonary artery hypertension, infective endocarditis and LA clot in these patients lead to increased mortality and morbidity. Appropriate early management of RHD can improve the quality of life. We need to focus on ARF prophylaxis in order to prevent chronic RHD. 2486 The role of nasopharyngeal load of Streptococcus pneumonia and its interaction as risk factors for childhood pneumonia in Vietnam Huong T. Vu1, Lay M. Yoshida1, Motoi Suzuki1, Anh T. Nguyen2, Paul Kilgore3, Anh D. Dang2, Koya Ariyoshi1 1Institute of Tropical Medicine, Nagasaki, Japan, 2National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam, 3International Vaccine Institute, Seoul, Republic of Korea Background: The role of nasopharyngeal bacterial load and its interaction with viral co-infection in the development of lower respiratory tract infections (LRTIs) remain unclear. We hypothesized that a high nasopharyngeal bacterial load may associate with LRTIs. Methods: A case-control study for pediatric LRTIs was conducted in NhaTrang, central Vietnam. A total of 555 consecutively hospitalised children were identified (274 radiographic confirmed pneumonia (RCP) and 281 other LRTIs) and 350 healthy controls were randomly selected from the community. PCR-based methods were used to detect three bacteria and 13 respiratory viruses in nasopharyngeal samples. Then quantitative measurements (real-time quantitative PCRs) of three species of bacteria: Streptococcus pneumoniae (SP), Hemophilus influenzae (HI) and Moraxella catarrhalis (MC) were analyzed among the three groups of participants both in the presence or absence of viral co-infection. Results: The median nasopharyngeal load of SP in RCP children was significantly higher than those in either healthy controls (P<0.0001) or other LRTI children (P<0.001). After controlling for potential confounders, high nasopharyngeal load of SP (>=107 bacteria/ml secretion) was strongly associated with RCP (adjusted odds ratio (OR), 3.26; 95% confidence interval (CI), 1.77 to 6.00). Children with viral co-infection had a 15-fold higher nasopharyngeal load of SP compared to those without viral co-infection in RCP group (1.4x107/ml versus 9.1x105/ml, p=0.0001). This association remained strong after adjustment (adjusted OR, 6.83; 95% CI, 2.35 to 19.84).No association was found between either high bacterial load of MC or HI and viral co-infection in either RCP or other LRTI groups (P>0.05). Conclusions: High nasopharyngeal load of SP was associated with RCP in Vietnamese children. Viral co-infection played an important role in increasing nasopharyngeal bacterial load of SP but not HI and MC. Thus, vaccines targeting respiratory