SEROLOGICAL DETECTION OF TOXOCARA CANIS INFECTION IN DOGS OF KERALA USING RECOMBINANT CATHEPSIN-L1 AND TOXOCARA EXCRETORY SECRETORY
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Date
2019-08-19
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE WAYANAD
Abstract
Present study was conducted on the expression of two important proteins
of Toxocara canis viz. cathepsin-L1 and TES-26 and to evaluate the diagnostic
potential of these two recombinant antigens in canine toxocarosis. Adult T. canis
worms were collected from puppies and total RNA was isolated and cDNA was
synthesized. The coding sequences of cathepsin-L1 and TES-26 genes,
respectively were amplified using specific forward and reverse primers. The PCR
products obtained from cDNA got amplified at 1083 and 793 bp, respectively of
cathepsin-L1 and TES-26. These proteins were subsequently expressed in
Escherichia coli pPROEXHT-b expression vector. Recombinant proteins were
purified using Ni-NTA chromatography. Recombinant cathepsin-L1 and TES-26
proteins were evaluated for their potential in the sero-detection of T. canis
infection in both owned and stray dogs by IgG ELISA. Sera collected from 157
owned dogs were screened for anti-T. canis IgG antibodies with recombinant
cathepsin-L1 and TES-26 antigen. ELISA with recombinant cathepsin-L1 showed
sero-reactivity of 39/157 (24.8 per cent) in owned dogs and stray dogs showed
18/40 (45 per cent). Likewise, ELISA with recombinant TES-26 gave seroreactivity with 78/157 (49.7 per cent) owned dogs. When the stray dogs were
screened with the same antigen showed a positive percentage of 28/40 (70 per
cent) was recorded. As a result of this comparative study of two recombinant
antigens, TES-26 gave highest positive ELISA reactivity for stray dogs followed
by cathepsin-L1. rTES-26 antigen is highly sensitive in the detection of T. canis
infection in owned and stray dogs compared to cathepsin-L1. Cross reactivity of
these antigens were checked with dog sera which is positive for other helminths
like, Ancylostoma caninum, Dirofilaria immitis, D. repens, Diphyllobothrium
latum, Spirometra spp. and Babesia gibsoni. The above results showed that two
recombinant antigens are cross-reacting with all the above canine parasites. The
two antigens are sensitive in the detection of T. canis infection in dogs; however,
the specificity of these antigens in canines needs to be further studied.