Antigenic Profile And Immunodiagnosis Of Cystic Echinococcosis
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Date
2007
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Tamil Nadu Veterinary and Animal Sciences University
Abstract
The antigenic profile of various hydatid antigens viz., Hydatid cyst
fluid antigen (HCFA), Protoscolices antigen (PSA) and Germinal membrane
antigen (GMA) were prepared and purified by gel filtration chromatography.
Characterisation by SDS-PAGE revealed 9 protein bands at 8, 16, 24, 38, 58, 68,
98, 116 and 205 kDa for HCFA, 3 protein bands at 29, 72 and 98 kDa for PSA
and 4 protein bands at 29, 38, 127 and 134 kDa for GMA. Western blot analysis
of these antigens revealed no cross reaction between them. Counter immuno
electrophoresis (CIEP) and western blot tests were used to identify hydatid
specific antigen. CIEP analysis of the 3 metacestode antigens revealed cross
reactivity between them.
Western blot analysis of fluid antigens of thesemetacestode antigens with anti HCFA serum recognized high molecular weight
protein bands in all antigens and low molecular 8 kDa antigen in hydatid cyst fluid
antigen only. Hence 8 kDa protein of HCFA was identified as non cross reactive
hydatid specific, immuno diagnostic antigen.
The non cross reactive hydatid specific immunodiagnostic 8 kDa
antigen from hydatid cyst fluid was prepared by DEAE-Sepharose fast flow anion
exchange chromatography. Cross reactive studies between 8 kDa Coenurus
and Cysticercus was carried out by CIEP using anti 8 kDa hyper immune sera
and found no cross reaction between them.
Hence the 8 kDa antigen was used for standardization of sero
diagnostic tests such as CIEP, Latex agglutination test (LAT), Enzyme linked
immuno electro transfer blot (EITB) and Flow through technique (FTT).
Evaluation of these tests were carried out with 150 cattle, 150 sheep hydatid
positive sea, 150 cattle and 150 sheep hydatid negative sera, 50 suspected and
50 negative human sera. The sensitivity, specificity, positive predictive value,
negative predictive value and efficacy in diagnosis of CE in sheep were 78.8, 93,
94.6, 74.6 and 84.6% for CIEP, 89, 98.5, 98.6, 88 and 93.3% for LAT, 92.5,
99.28, 99.3, 92 and 95.6% for EITB and 94.9, 99.3, 99.33, 94.6 and 97% for FTT
respectively.
The sensitivity, specificity, positive predictive value, negative
predictive value and efficiency for cystic echinococcosis in cattle were 75, 89.6,
92, 69.3 and 80.6% for CIEP, 85.5, 94, 94.6, 84 and 89.3% for LAT, 87.8, 96.29,
96.6, 86.6 and 91.6% for EITB and 92.4, 97.18, 97.33, 92 and 94.66% for FTTrespectively.
All the four tests equally detected 2 positive cases in man.
However the sensitivity and efficiency of FTT was higher than other tests. EITB
and FTT had equal specificity in detecting antibodies in cattle and sheep. The
current study is a pioneering work on standardization and evaluation of four
serological tests viz., CIEP, LAT, EITB and FTT in diagnosis of CE in animals
and man using the hydatid specific purified 8 kDa antigen.
Flow through
technique which was not used in the diagnosis of hydatidosis was adopted and
found to be a simple and sensitive test in diagnosis of CE in man and animals
with easy applicability in field condition.
A kit based on this test can be
developed for diagnosis of CE in man and animals.