Comparison of different serological methods to detect antibodies specific to Neospora caninum in bovine and canine sera (original) (raw)

2014, Journal of Veterinary Diagnostic Investigation

Brief Research Reports Neospora caninum, the causative agent of neosporosis, is an apicomplexan intracellular parasite causing paresis in dogs and abortion in cattle. 2,3 Studies of the domestic life cycle of the parasite have shown that dogs are both intermediate and definitive hosts, whereas cattle are natural intermediate hosts. 2 Diagnosis of neosporosis can be achieved using histology, immunohistochemical staining, polymerase chain reaction, and serology. 4 Serological tests have the advantage that they can be applied antemortem, but suffer from not being able to discriminate between latent and acute infections. 4 Serological techniques for the specific detection of bovine and canine antibodies to N. caninum include the indirect fluorescent antibody test (IFAT), 2 immunoblotting (IB), 1 the direct agglutination test (DAT), 17 and a variety of enzymelinked immunosorbent assays (ELISAs). 5 The accepted reference method for serological diagnosis is IFAT, 6 with IFAT having been used in many species and generally considered the "gold standard" when evaluating new methods. 2-4 However, use of whole tachyzoite antigen in any serological assay may result in high background absorbance values and cross-reactivity with antibodies against related parasites such as Toxoplasma gondii. 5 Compared with the native antigens, recombinant antigens are easily produced in large quantities and can be readily standardized for diagnostic assays. In addition, their use may minimize the risk of crossreactivity with other parasite species. 15 The molecular search for diagnostic antigens for N. caninum infection has focused on the identifying immunodominant antigens that are recognized by sera from infected animals. In this sense, the dense granule proteins, NcGRA7 and NcGRA6, of N. caninum were shown to be effective candidates to diagnose N. caninum infection in cattle when used in ELISA. 9-11 In contrast to the other serological techniques (e.g., ELISA, IFAT, IB), which are laborious and time-consuming and require specialized expertise and equipment, the latex agglutination test (LAT) is a technique that is very simple to carry out, making it suitable for clinical or field applications. 18 In the present study, the performance of a LAT using recombinant NcGRA6 was evaluated for the serological detection of specific antibodies to N. caninum and compared 5480V DIXXX10.1177/1040638713515480Neospora caninum serological methodsGhalmi et al.