Development of a pseudotype neutralisation assay-based diagnostic kit for in-field vaccine evaluation and serosurveillance for highly pathogenic viruses

Virus neutralisation assays quantitatively detect levels of neutralising antibody response against antigenic surface glycoproteins on many viruses, following vaccination or natural infection. However, high biosafety level requirements and extensive personnel training prevent these tests from broad laboratory application, especially in resource-limited regions. Therefore, development of methods for vaccine evaluation and serosurveillance which can be used in these areas are urgently required. To address these issues lentiviral pseudotype viruses (PVs) have been utilised. PVs are chimeric, replication-deficient particles that mimic the infective mechanisms of their wild-type counterparts. Pseudotype neutralisation assays (PNAs) circumvent the requirement for high biosafety precautions whilst maintaining comparable sensitivity and specificity with existing assays. This study ascertains pseudotype stability through subjection to environmental conditions likely to be encountered in assembly, transport and usage of a PNA-based diagnostic kit. Pseudotypes of clinically-important viruses (e.g. influenza and lyssaviruses) have been used and titres monitored through cumulative freeze-thaw cycles, lyophilisation, and varying temperatures and humidities. Results demonstrated the ability to retain acceptable levels of virus activity following treatments, indicating the potential of PNA-based kits for global distribution and diagnostic application. Such flexible and durable kits could permit accurate in-field vaccine evaluation and serosurveillance for many viruses of endemic and pandemic concern.