Anti-CHIKV Monoclonal antibody, Clone F37D5

Background: A longitudinal cohort study performed in Cebu City, Philippines found that the presence of pre-existing chikungunya virus (CHIKV) neutralizing antibodies (NAb) was associated with a decreased risk of symptomatic CHIKV infection. However, the relationship between pre-existing NAb and the risk of subclinical seroconversion has not been well described. Methods: Data were analyzed from a longitudinal cohort aged 6 months to 83 years who underwent active fever surveillance in Cebu City, Philippines from 2012 to 2014. Participants with a history of fever underwent acute and 3-week convalescent visits with blood collection, and annual visits at baseline, 12 months, and 24 months. Symptomatic CHIKV infections were detected by PCR of acute illness sera. Subclinical seroconversion was defined as a >= 8-fold rise in 80% plaque reduction neutralization test (PRNT80) titer between annual visits without intervening symptomatic infection. Results: Among 854 participants who completed the 12-month visit (year 1) and 765 who completed the 24-month visit (year 2), 25 symptomatic CHIKV infections and 104 subclinical seroconversions occurred among 615 individuals with no detectable pre-year NAb in year 1 and 444 in year 2, while no symptomatic infections and one subclinical seroconversion occurred in those with a pre-year PRNT80 titer >= 1:10. Pre-year PRNT80 titer >= 1:10 was associated with zero relative risk of symptomatic CHIKV infection and 0.018 risk of subclinical seroconversion. Conclusions: The presence of detectable pre-existing CHIKV NAb correlated with a decreased risk of both symptomatic CHIKV infection and subclinical seroconversion. These findings support the potential use of CHIKV NAb titer as a surrogate endpoint of protection from infection for vaccine development. (C) 2020 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.

BackgroundMosquitoes are the deadliest animals in the world. Their ability to carry and spread diseases to humans causes millions of deaths every year. Due to the lack of efficient vaccines, the control of mosquito-borne diseases primarily relies on the management of the vector. Traditional control methods are insufficient to control mosquito populations. The sterile insect technique (SIT) is an additional control method that can be combined with other control tactics to suppress specific mosquito populations. The SIT requires the mass-rearing and release of sterile males with the aim to induce sterility in the wild female population. Samples collected from the environment for laboratory colonization, as well as the released males, should be free from mosquito-borne viruses (MBV). Therefore, efficient detection methods with defined detection limits for MBV are required. Although a one-step reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) method was developed to detect arboviruses in human and mosquito samples, its detection limit in mosquito samples has yet to be defined.MethodsWe evaluated the detection sensitivity of one step RT-qPCR for targeted arboviruses in large mosquito pools, using pools of non-infected mosquitoes of various sizes (165, 320 and 1600 mosquitoes) containing one infected mosquito body with defined virus titers of chikungunya virus (CHIKV), usutu virus (USUV), West Nile virus (WNV) and Zika virus (ZIKV).ResultsCHIK, USUV, ZIKV, and WNV virus were detected in all tested pools using the RT-qPCR assay. Moreover, in the largest mosquito pools (1600 mosquitoes), RT-qPCR was able to detect the targeted viruses using different total RNA quantities (10, 1 and 0.1 ng per reaction) as a template. Correlating the virus titer with the total RNA quantity allowed the prediction of the maximum number of mosquitoes per pool in which the RT-qPCR can theoretically detect the virus infection.ConclusionsMosquito-borne viruses can be reliably detected by RT-qPCR assay in pools of mosquitoes exceeding 1000 specimens. This will represent an important step to expand pathogen-free colonies for mass-rearing sterile males for programmes that have a SIT component by reducing the time and the manpower needed to conduct this quality control process.