Development of a pseudovirus based assay for measuring neutralizing antibodies against coxsackievirus B5

Pseudotyped Viruses for Enterovirus

Using a non-pathogenic pseudotyped virus as a surrogate for a wide-type virus in scientific research complies with the recent requirements for biosafety. Enterovirus (EV) contains many species of viruses, which are a type of nonenveloped virus. The preparation of its corresponding pseudotyped virus often needs customized construction compared to some enveloped viruses. This article describes the procedures and challenges in the construction of pseudotyped virus for enterovirus (pseudotyped enterovirus, EVpv) and also introduces the application of EVpv in basic virological research, serological monitoring, and the detection of neutralizing antibody (NtAb).

Comparison of the neutralizing activities of antibodies in clinical sera against both Sabin and wild-type polio pseudoviruses

The cost-effectiveness of the Sabin inactivated poliovirus vaccine derived from the Sabin strains (S-IPV) and its reduced biosecurity risks during its manufacture make it the vaccine of choice over the IPVs derived from wild-type polioviruses. However, it is difficult to evaluate whether S-IPVs can achieve wild-type poliovirus containment in China, making its development there less attractive. To facilitate the development and adoption of S-IPVs in China, the aim of this study was to develop an alternative neutralizing assay using either a polio pseudovirus derived from a Sabin strain (S-pNA) or one derived from a wild-type strain (w-pNA) to replace the conventional neutralizing assay which uses live polioviruses. A total of 100 sera were collected from children immunized with an oral poliovirus vaccine and their antibody titers were assessed by both the S-pNA and w-pNA. The results showed that this method was feasible for the quantification of neutralizing antibody activities in the sera of the vaccinated individuals. The Wilcoxon signed-rank sum test indicated that the neutralizing antibody titers obtained against the Sabin strains were higher than those obtained with the wild-type strains for types 1 and 3, while for type 2, the titers against the wild-type strains were higher than those against the Sabin strains (p < 0.001 for all three types). It is hoped that this assay could be used to assess whether immune sera by the S-IPV possess adequate neutralizing capacity against both attenuated and wild-type poliovirus strains.

Development of a pseudovirus-based assay for measuring neutralizing antibodies against Coxsackievirus A10

Coxsackievirus A10 (CV-A10) has recently emerged as a major pathogen of hand, foot, and mouth disease in children worldwide. Currently no effective treatments are available; development of anti-CV-A10 vaccine is a most cost-effective way for CV-A10 prevention. Robust assay to measure neutralizing antibody (NtAb) titres elicited by vaccination would greatly prompt anti-CV-A10 vaccine development. Compare to the traditional neutralization assay based on inhibition of cytopathic effects (herein after referred to as cNT) which is time-consuming and labor-intensive, in this study we developed an efficient high-throughput neutralization antibody assay based on CV-A10 pseudoviruses (herein after referred to as pNT). In the pNT, anti-CV-A10 NtAb titre was negatively corresponded with the relative luminescent unit (RLU) produced by luciferase reporter gene incorporated in pseudovirus genome. As described in this study, the NtAb against CV-A10 could be detected within 10-16 h, anti- CV-A10 NtAb in 67 human serum samples were measured in parallel with pNT and cNT assays, a good correlation (r = 0.83,p < .0001) and good agreement(97%) were shown between cNT and pNT, indicating that the pNT provides a rapid and convenient procedure for measuring NtAb production against anti-CV-A10 NtAb measurement.

A surrogate assay for measuring Coxsackievirus A6 neutralizing antibodies

Coxsackievirus A6 (CV-A6) is one of pathogens causing hand, foot and mouth disease (HFMD) and becomes a new challenge to HFMD control. In this study, we first built a single-round pseudovirus infection system for CV-A6, and then developed a pseudovirus luciferase assay (PVLA) for anti-CV-A6 neutralizing antibody (NtAb) quantification. Since cytopahtic effect (CPE) is considered as the gold standard test for anti-enterovirus NtAb detection, a comparison study has been performed using 318 clinical serum samples, as measured both by PVLA and CPE. The sensitivity and specificity of PVLA was 94.9% (95% CI between 90.8-97.5%) and 92.7% (95% CI between 86.6-96.6%), respectively. Statistical analysis revealed that PVLA and CPE were highly correlated (spearman r = 0.931, P < 0.0001) and in good agreement (94.0%, 95% CI between 90.8-96.4%), showing that PVLA could be used as a surrogate assay for anti-CV-A6 NtAb detection and served as a valuable tool for CV-A6 vaccine evaluation and CV-A6 epidemiological surveillance.