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The development of vaccines against flaviviruses, including Zika virus (ZIKV) and dengue virus (DENV), continues to be a major challenge, hindered by the lack of efficient and reliable methods for screening neutralizing activity of sera or antibodies. To address this need, we previously developed a plasmid-based, replication-incompetent DENV reporter virus particle (RVP) production system as an efficient and safe alternative to the Plaque Reduction Neutralization Test (PRNT). As part of the response to the 2015-2016 ZIKV outbreak, we developed pseudo-infectious ZIKV RVPs by modifying our DENV RVP system. The use of ZIKV RVPs as critical reagents in human clinical trials requires their further validation using stability and reproducibility metrics for large-scale applications. In the current study, we validated ZIKV RVPs using infectivity, neutralization, and enhancement assays with monoclonal antibodies (MAbs) and human ZIKV-positive patient serum. ZIKV RVPs are antigenically equivalent to live virus based on binding ELISA and neutralization results and are nonreplicating based on the results of live virus replication assays. We demonstrate reproducible neutralization titer data (NT50 values) across different RVP production lots, volumes, time frames, and laboratories. We also show RVP stability across experimentally relevant time intervals and temperatures. Our results demonstrate that ZIKV RVPs provide a safe, high-throughput, and reproducible reagent for large-scale, long-term studies of neutralizing antibodies and sera, which can facilitate large-scale screening and epidemiological studies to help expedite ZIKV vaccine development., Competing Interests: I have read the journal's policy and the authors of this manuscript have the following competing interests. Integral Molecular offers ZIKV RVPs as a commercial reagent. J. C. Whitbeck, A. Thomas, K. Kadash-Edmondson, A. Grinyo-Escuer, Lewis J. Stafford, E. Davidson, B. J. Doranz are all current or former members of Integral Molecular. B. J. Doranz is a shareholder of Integral Molecular.

Background & Aims: Red blood cell (RBC) indices have been demonstrated to be associated with fatty liver disease (FLD) and metabolic syndrome. However, controversy exists regarding the relationship of RBC indices with FLD to date and few has focused on RBC count. This study aimed to explore the association between RBC count and risk of FLD in Southern Chinese adults., Methods: A hospital-based cross-sectional study was performed in two hospital health examination centers, including information on ultrasonography-diagnosed FLD, anthropometric indices and biochemical measurements. Covariance analysis was used to evaluate group differences. After quintile classification of RBC counts, logistic regression analysis was conducted to evaluate the odds ratios (ORs) of FLD., Results: This study consisted of 8618 subjects (4137 men and 4481 women) aged between 20 and 89 years. FLD cases had higher RBC counts than non-FLD cases in both genders (P<0.001). The prevalence rates of FLD increased with the RBC quintiles in both genders (all P trend<0.001), and were higher in men than women. Binary logistic regression analysis showed positive association between RBC count and FLD, and the OR (95% confidence interval (CI)) were 2.56 (2.06-3.18) in men and 3.69 (2.74-4.98) in women, respectively, when comparing Q5 with Q1. Stratified analyses showed similar trends among subjects with and without FLD risk factors. Gender independent results were similar to gender dependent results., Conclusions: Elevated RBC count is independently associated with high risk of FLD, suggesting that the RBC count may be a potential risk predictor for FLD., Competing Interests: The authors have declared that no competing interests exist.