Enzyme-linked immunosorbent assays for the detection of equine antibodies specific to a recombinant Fasciola hepatica surface antigen in an endemic area

Abstract

The utility of an enzyme-linked immunosorbent assay to determine the sensitization against the trematode Fasciola hepatica in horses from an endemic area (NW Spain) was assessed. Blood samples were collected from 536 horses and tested against a 2.9-kDa recombinant surface protein (FhrAPS) to estimate the presence of IgG antibodies. Data were analysed regarding several intrinsic (age, gender and breed) and extrinsic factors (aptitude and housing). The farm size (number of horses/farm) was also considered. Sixty percent (95% CI 56, 64) of the horses were positive to the FhrAPS-ELISA, with a significantly higher seroprevalence in the mares (67%). Foals reached the lowest percentage of sensitization against the trematode (12%), and a significant positive correlation between the seroprevalence of fasciolosis and the age of the horses was established. When considering all the factors together, the seroprevalence of fasciolosis was initially classified into two groups (nodes) regarding the age of the horses. The node composed of the horses older than 1 year was then divided into two other clusters according to their gender. The mares were finally classified and grouped into two nodes regarding their breed. We concluded that the FhrAPS-ELISA is very useful for the demonstration of specific equine IgG antibodies against F. hepatica. An elevated risk of exposition to this trematode in horses maintained in endemic areas was proven. The possible role of horses as reservoirs for F. hepatica infections is discussed.

Determination of exposure to Fasciola hepatica in horses from Uruguay using a recombinant-based ELISA

“…The presence of antibodies against F. hepatica was age-related, with the lowest values in the youngest horses and the highest values in the oldest animals. These data are consistent with previous results suggesting a cumulative effect of infection throughout the life of the horse (Arias et al 2012a;Getachew et al 2010). Previous investigations in Uruguay indicate that calves exhibit the highest seroprevalence against F. hepatica crude antigens (Sanchis et al 2011).…”

“…Likewise, the highest seroprevalences were obtained among the English Pure Breed, Arab and Anglo-Arab equines from Spain (85%, 75% and 60%, respectively). However, significant differences were not observed in the seropositivity regarding the equine breed (Arias et al 2012a). It is possible that the horses are allowed access to paddocks for exercise, which may increase the risk of exposure to the metacercariae.…”

“…Because it is difficult for Fasciola to reach the adult stage in horses, the excretion of F. hepatica eggs in the faeces occurs only occasionally; therefore, the role of horses as potential trematode reservoirs has been underestimated (Arias et al 2012a). However, the delay in mature trematode development allows the immune system to stay in contact with the trematodes and antigens, thereby eliciting a strong humoral immune response (Phiri et al 2006).…”

“…The presence of IgG antibodies against the liver trematode F. hepatica was evaluated using an ELISA with the FhrAPS recombinant surface protein. The ELISA was 83% sensitive and 86% specific (Arias et al 2012a). In brief, 1 µg/ml FhrAPS was added to the wells of microtitre plates containing sera (tested in duplicate) diluted 1/100 in 10% PTL (PBS, 0.3% Tween 20 and 10% skimmed milk) and horseradish peroxidase conjugated to rabbit anti-horse IgG (Nordic Immunology Laboratories, The Netherlands) at a 1/1000 dilution.…”

“…The identification of horses exposed to F. hepatica using immunoenzymatic probes has previously been proposed (Acici et al 2013). In a recent study, an ELISA with the FhrAPS recombinant surface antigen was used to demonstrate the high seroprevalence of fasciolosis among horses feeding on grasslands formerly pastured by ruminants (Arias et al 2012a). Because horses and cattle regularly share the same pastures in Uruguay, exposure to the liver trematode in equines from this country has been evaluated in this study.…”