Abstract Description

African horse sickness (AHS), caused by the AHS virus (AHSV), is a highly infectious, non-contagious, vector-borne disease that can lead to high mortality in horses and severe economic losses. Laboratory confirmation of disease is imperative for implementation of control measures. Integral to laboratory diagnosis is choosing appropriate specimens, correct sampling and safe transportation for biosafety and biosecurity reasons, as well as sample integrity. The study investigated the use of Flinders Technology Associates (FTA) cards (Ahmed et al., 2012) for collecting and safe transportation of blood samples for use in the detection of AHSV antibodies and serotyping. The stability of blood samples stored on FTA cards under temperatures of 2-8 °C and -20 °C for up to 18 months was assessed. Paired field (n = 127) and experimental (n = 20) equine blood and sera were utilized. Blood samples were blotted on commercially procured FTA cards (GE Healthcare, Whatman, International Limited, UK)) and elutions prepared following the manufacturer’s instructions. Corresponding sera were used as standard sample matrix for comparison. Recombinant VP7 antigen-based indirect enzyme-linked immunosorbent assay (I-ELISA) and the plaque reduction neutralization test (PRNT) were used for anti-AHSV antibody detection and serotyping, respectively. Presence of viral genomic material was detected using a hemi-nested Reverse Transcription-Polymerase Chain Reaction (hnRT-PCR) assay. Virus isolation (VI) in tissue culture was used to determine the presence of viable AHSVs in samples. The study showed that AHSV antibodies could be detected from FTA card extracts with 100% accuracy for up to 18 months, especially when stored at lower temperatures. Serotyping was possible, but sensitivity decreased with time. Live viruses could not be isolated from extracts of FTA cards, blotted with AHSV positive blood, proving safety of transportation of blood samples on the cards. Viral nucleic acid was, however, detected from the extracts, confirming suitability for use in molecular diagnostics and downstream processes. It was concluded that FTA cards are reliable and efficient materials for the collection, preservation, and transportation of blood samples for AHS laboratory diagnosis, especially in endemic regions. Storage at lower temperatures is recommended for increased stability. Utilization of the method for serotyping would require further optimization.