Development and performance of a serological enzyme-linked immunosorbent assay (ELISA) for ruminant liver fluke disease
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Date
2024-02-02Embargo Date
2026-02-01
Author
López Corrales, Jesús
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Abstract
Fasciola hepatica, also known as the liver fluke, is the causative agent of fasciolosis.
It is classified by the World Health Organisation as a neglected tropical disease,
affecting both humans and livestock globally. Moreover, infections caused by this
parasite cause multimillion economic losses to the livestock industry. In order to
minimise the effects of F. hepatica infections by applying the appropriate management
and control interventions, it is essential to include the use of a reliable diagnostic
method that is also effective in determining infections as early as possible with high
sensitivity and specificity. Among the available methods, we show that serum-ELISA
based on the detection of antibodies against cathepsin L1 peptidase has a high
efficacy detecting infections at every developmental stage of the flukes in their
definitive hosts. However, discovering new antigens is essential to provide more
options for the development of liver fluke diagnostics and vaccines, allowing us to use
one or more antigens to differentiate infected from vaccinated animals (DIVA). In this
work, we evaluated the performance of an array of molecules produced by F. hepatica
as antigens for indirect ELISA tests in comparison with recombinant cathepsin L1
(rFhCL1). Four antigens, namely rFhGAPDH, rFhGPI, rFhEnolase and rFhFBPA,
were recombinantly produced during this study and assessed in ELISA, along with
several more recombinant antigens (rFhHDM, rFhLAP, rFhPrx, rFhSOD1, rFhSOD3,
rFhTrx, rFhCL2, rFhStf1 and rFhKT1), to analyse IgG responses in sera samples of
sheep and cattle that were both experimentally and naturally infected. None of the
studied antigens performed better than rFhCL1 because of their lower
immunogenicity. In addition, some of them showed high background levels due to
antibody cross-reactivity. In the case of E. coli produced antigens, this was possibly
caused by E. coli infections in the animals or natural antibodies targeting E. coli
proteins. In the case of P. pastoris produced antigens, the cross-reactivity possibly
resulted from glycans present in the recombinant proteins. These sugar residues may
be recognised by host antibodies produced after being fed with yeast-rich
supplemented food. Finally, we studied a potential method to determine liver fluke
infection stages, namely by calculating the ratio anti-rFhCL1/anti-rFhCB3 immune
responses, with promising results. Future investigation including a larger number of
samples and complementary parasitological data will be key to further prove its
applicability.