METHODOLOGY/PRINCIPAL FINDINGS: We characterized human immune sera collected during two independent outbreaks in Malaysia of the Asian genotype in 2006 and the ECSA genotype in 2008-2010. Neutralizing capacity was analyzed against representative clinical isolates as well as viruses rescued from infectious clones of ECSA and Asian CHIKV. Using whole virus antigen and recombinant E1 and E2 envelope glycoproteins, we further investigated antibody binding sites, epitopes, and antibody titers. Both ECSA and Asian sera demonstrated stronger neutralizing capacity against the ECSA genotype, which corresponded to strong epitope-antibody interaction. ECSA serum targeted conformational epitope sites in the E1-E2 glycoprotein, and E1-E211K, E2-I2T, E2-H5N, E2-G118S and E2-S194G are key amino acids that enhance cross-neutralizing efficacy. As for Asian serum, the antibodies targeting E2 glycoprotein correlated with neutralizing efficacy, and I2T, H5N, G118S and S194G altered and improved the neutralization profile. Rabbit polyclonal antibody against the N-terminal linear neutralizing epitope from the ECSA sequence has reduced binding capacity and neutralization efficacy against Asian CHIKV. These findings imply that the choice of vaccine strain may impact cross-protection against different genotypes.
CONCLUSION/SIGNIFICANCE: Immune serum from humans infected with CHIKV of either ECSA or Asian genotypes showed differences in binding and neutralization characteristics. These findings have implications for the continued outbreaks of co-circulating CHIKV genotypes and effective design of vaccines and diagnostic serological assays.
METHODS: To determine Zika virus (ZIKV) seroprevalence in Kuala Lumpur, Malaysia, 1085 serum samples from 2012, 2014-2015 and 2017 were screened for anti-ZIKV antibodies using a ZIKV NS1 blockade-of-binding assay. Reactive samples were confirmed using neutralization assays against ZIKV and the four dengue virus (DENV) serotypes. A sample was possible ZIKV seropositive with a ZIKV 50% neutralization (NT50) titre ≥20. A sample was probable ZIKV seropositive if, in addition, all DENV NT50 titres were <20 or the ZIKV NT50 titre was >4-fold greater than the highest DENV NT50 titre.
RESULTS: We found low rates of possible ZIKV seropositivity (3.3% [95% confidence interval {CI} 2.4 to 4.6]) and probable ZIKV seropositivity (0.6% [95% CI 0.3 to 1.4]). Possible ZIKV seropositivity was independently associated with increasing age (odds ratio [OR] 1.04 [95% CI 1.02 to 1.06], p<0.0001) and male gender (OR 3.5 [95% CI 1.5 to 8.6], p=0.005).
CONCLUSIONS: The low ZIKV seroprevalence rate, a proxy for population immunity, does not explain the low incidence of Zika in dengue-hyperendemic Kuala Lumpur. Other factors, such as the possible protective effects of pre-existing flavivirus antibodies or reduced transmission by local mosquito vectors, should be explored. Kuala Lumpur is at high risk of a large-scale Zika epidemic.
METHODOLOGY/PRINCIPAL FINDINGS: We assessed oral susceptibility of Malaysian Ae. aegypti and Ae. albopictus by real-time PCR to an Australian RRV strain SW2089. Replication kinetics in midgut, head and saliva were determined at 3 and 10 days post-infection (dpi). With a 3 log10 PFU/ml blood meal, infection rate was higher in Ae. albopictus (60%) than Ae. aegypti (15%; p<0.05). Despite similar infection rates at 5 and 7 log10 PFU/ml blood meals, Ae. albopictus had significantly higher viral loads and required a significantly lower median oral infectious dose (2.7 log10 PFU/ml) than Ae. aegypti (4.2 log10 PFU/ml). Ae. albopictus showed higher vector competence, with higher viral loads in heads and saliva, and higher transmission rate (RRV present in saliva) of 100% at 10 dpi, than Ae. aegypti (41%). Ae. aegypti demonstrated greater barriers at either midgut escape or salivary gland infection, and salivary gland escape. We then assessed seropositivity against RRV among 240 Kuala Lumpur inpatients using plaque reduction neutralization, and found a low rate of 0.8%.
CONCLUSIONS/SIGNIFICANCE: Both Ae. aegypti and Ae. albopictus are susceptible to RRV, but Ae. albopictus displays greater vector competence. Extensive travel links with Australia, abundant Aedes vectors, and low population immunity places Kuala Lumpur, Malaysia at risk of an imported RRV outbreak. Surveillance and increased diagnostic awareness and capacity are imperative to prevent establishment of new arboviruses in Malaysia.
METHODS: Data from the CHInese Medicine NeuroAiD Efficacy on Stroke (CHIMES) and CHIMES-Extension (CHIMES-E) studies were analyzed. CHIMES-E was a 24-month follow-up study of subjects included in CHIMES, a multi-centre, double-blind placebo-controlled trial which randomized subjects with acute ischemic stroke, to either MLC601 or placebo for 3 months in addition to standard stroke treatment and rehabilitation. Subjects were stratified according to whether they received or did not receive persistent rehabilitation up to month (M)3 (non- randomized allocation) and by treatment group. The modified Rankin Scale (mRS) and Barthel Index were assessed at month (M) 3, M6, M12, M18, and M24.
RESULTS: Of 880 subjects in CHIMES-E, data on rehabilitation at M3 were available in 807 (91.7%, mean age 61.8 ± 11.3 years, 36% female). After adjusting for prognostic factors of poor outcome (age, sex, pre-stroke mRS, baseline National Institute of Health Stroke Scale, and stroke onset-to-study-treatment time), subjects who received persistent rehabilitation showed consistently higher treatment effect in favor of MLC601 for all time points on mRS 0-1 dichotomy analysis (ORs 1.85 at M3, 2.18 at M6, 2.42 at M12, 1.94 at M18, 1.87 at M24), mRS ordinal analysis (ORs 1.37 at M3, 1.40 at M6, 1.53 at M12, 1.50 at M18, 1.38 at M24), and BI ≥95 dichotomy analysis (ORs 1.39 at M3, 1.95 at M6, 1.56 at M12, 1.56 at M18, 1.46 at M24) compared to those who did not receive persistent rehabilitation.
CONCLUSIONS: More subjects on MLC601 improved to functional independence compared to placebo among subjects receiving persistent rehabilitation up to M3. The larger treatment effect of MLC601 was sustained over 2 years which supports the hypothesis that MLC601 combined with rehabilitation might have beneficial and sustained effects on neuro-repair processes after stroke. There is a need for more data on the effect of combining rehabilitation programs with stroke recovery treatments.