Longitudinal analysis of the human antibody response to Chikungunya virus infection: implications for serodiagnosis and vaccine development.

Chikungunya virus (CHIKV) is an alphavirus which causes chronic and incapacitating arthralgia in humans. Although previous studies have shown that antibodies against the virus are produced during and after infection, the fine specificity of the antibody response against CHIKV is not known. Here, using plasma from patients at different times postinfection, we characterized the antibody response against various proteins of the virus. We have shown that the E2 and E3 glycoproteins and the capsid and nsP3 proteins are targets of the anti-CHIKV antibody response. Moreover, we have identified the different regions in these proteins which contain the linear epitopes recognized by the anti-CHIKV antibodies and determined their structural localization. Data also illustrated the effect of a single K(252)Q amino acid change at the E2 glycoprotein that was able to influence antibody binding and interaction between the antibodies and epitope because of the changes of epitope-antibody binding capacity. This study provides important knowledge that will not only aid in the understanding of the immune response to CHIKV infection but also provide new knowledge in the design of modern vaccine development. Furthermore, these pathogen-specific epitopes could be used for future seroepidemiological studies that will unravel the molecular mechanisms of human immunity and protection from CHIKV disease.

A before-after interventional trial of dispatcher-assisted cardio-pulmonary resuscitation for out-of-hospital cardiac arrests in Singapore.

AIM: To evaluate the effects of a comprehensive dispatcher-assisted CPR (DACPR) training program on bystander CPR (BCPR) rate and the outcomes of out-of-hospital cardiac arrest (OHCA) in Singapore. METHODS: This is an initial program evaluation of a national DACPR intervention. A before-after analysis was conducted using OHCA cases retrieved from a local registry and DACPR information derived from audio recordings and ambulance notes. The primary outcomes were survival to admission, survival at 30 days post-arrest and good functional recovery. RESULTS: Data was collected before the intervention (April 2010 to December 2011), during the run-in period (January 2012 to June 2012) and after the intervention (July 2012 to February 2013). A total of 2968 cases were included in the study with a mean age of 65.6. Overall survival rate was 3.9% (116) with good functional recovery in 2.2% (66) of the patients. BCPR rate increased from 22.4% to 42.1% (p<0.001) with odds ratio (OR) of 2.52 (95% confidence interval [CI]: 2.09-3.04) and ROSC increased significantly from 26.5% to 31.2% (p=0.02) with OR of 1.26 (95%CI: 1.04-1.53) after the intervention. Significantly higher survival at 30 days was observed for patients who received BCPR from a trained person as compared to no BCPR (p=0.001, OR=2.07 [95%CI: 1.41-3.02]) and DACPR (p=0.04, OR=0.30 [95%CI: 0.04-2.18]). CONCLUSION: A significant increase in BCPR and ROSC was observed after the intervention. There was a trend to suggest improved survival outcomes with the intervention pending further results from the trial.

Early Hyperglycemia in Pediatric Traumatic Brain Injury Predicts for Mortality, Prolonged Duration of Mechanical Ventilation, and Intensive Care Stay.

We aim to study the association between hyperglycemia and in-hospital outcomes among children with moderate and severe traumatic brain injury (TBI). This retrospective cohort study was conducted in a tertiary pediatric hospital between 2003 and 2013. All patients < 16 years old who presented to the Emergency Department within 24 hours of head injury with a Glasgow Coma Scale (GCS) ≤ 13 were included. Our outcomes of interest were death, 14 ventilation-free, 14 pediatric intensive care unit- (PICU-) free, and 28 hospital-free days. Hyperglycemia was defined as glucose > 200 mg/dL (11.1 mmol/L). Among the 44 patients analyzed, the median age was 8.6 years (interquartile range (IQR) 5.0-11.0). Median GCS and pediatric trauma scores were 7 (IQR 4-10) and 4 (IQR 3-6), respectively. Initial hyperglycemia was associated with death (37% in the hyperglycemia group versus 8% in the normoglycemia group, p = 0.019), reduced median PICU-free days (6 days versus 11 days, p = 0.006), and reduced median ventilation-free days (8 days versus 12 days, p = 0.008). This association was however not significant in the stratified analysis of patients with GCS ≤ 8. Conclusion. Our findings demonstrate that early hyperglycemia is associated with increased mortality, prolonged duration of mechanical ventilation, and PICU stay in children with TBI.

Clustering HLA class I superfamilies using structural interaction patterns.

Human leukocyte antigen (HLA) class I molecules are critical components of the cell-mediated immune system that bind and present intracellular antigenic peptides to CD8(+) T cell receptors. To understand the interaction mechanism underlying human leukocyte antigen (HLA) class I specificity in detail, we studied the structural interaction characteristics of 16,393 nonameric peptides binding to 58 HLA-A and -B molecules. Our analysis showed for the first time that HLA-peptide intermolecular bonding patterns vary among different alleles and may be grouped in a superfamily dependent manner. Through the use of these HLA class I 'fingerprints', a high resolution HLA class I superfamily classification schema was developed. This classification is capable of separating HLA alleles into well resolved, non-overlapping clusters, which is consistent with known HLA superfamily definitions. Such structural interaction approach serves as an excellent alternative to the traditional methods of HLA superfamily definitions that use peptide binding motifs or receptor information, and will help identify appropriate antigens suitable for broad-based subunit vaccine design.

Early neutralizing IgG response to Chikungunya virus in infected patients targets a dominant linear epitope on the E2 glycoprotein.

Chikungunya virus (CHIKV) and related arboviruses have been responsible for large epidemic outbreaks with serious economic and social impact. The immune mechanisms, which control viral multiplication and dissemination, are not yet known. Here, we studied the antibody response against the CHIKV surface antigens in infected patients. With plasma samples obtained during the early convalescent phase, we showed that the naturally-acquired IgG response is dominated by IgG3 antibodies specific mostly for a single linear epitope 'E2EP3'. E2EP3 is located at the N-terminus of the E2 glycoprotein and prominently exposed on the viral envelope. E2EP3-specific antibodies are neutralizing and their removal from the plasma reduced the CHIKV-specific antibody titer by up to 80%. Screening of E2EP3 across different patient cohorts and in non-human primates demonstrated the value of this epitope as a good serology detection marker for CHIKV infection already at an early stage. Mice vaccinated by E2EP3 peptides were protected against CHIKV with reduced viremia and joint inflammation, providing a pre-clinical basis for the design of effective vaccine against arthralgia-inducing CHIKV and other alphaviruses.