First Blindness Cases of Horses Infected with Setaria Digitata (Nematoda: Filarioidea) in the Republic of Korea

Ocular setariases of cattle were reported but those of equine hosts have never been reported in the Republic of Korea (Korea). We found motile worms in the aqueous humor of 15 horses (Equus spp.) from 12 localities in southern parts of Korea between January 2004 and November 2017. After the affected animals were properly restrained under sedation and local anesthesia, 10 ml disposable syringe with a 16-gauge needle was inserted into the anterior chamber of the affected eye to successfully remove the parasites. The male worm that was found in 7 of the cases showed a pair of lateral appendages near the posterior terminal end of the body. The papillar arrangement was 3 pairs of precloacal, a pair of adcloacal, and 3 pairs of postcloacal papillae, plus a central papilla just in front of the cloaca. The female worms found in the eyes of 8 horses were characterized by the tapering posterior terminal end of the body with a smooth knob. Worms were all identified as Setaria digitata (von Linstow, 1906) by the morphologic characteristics using light and electron microscopic observations. This is the first blindness cases of 15 horses infected with S. digitata (Nematoda: Filarioidea) in Korea.

Immune response of electroeluted detergent soluble 29 kDa antigen from Setaria digitata (Von Linstow).

Filariasis is one of the typical parasitic infections which cause immune suppression during the course of infection in both humans and experimental animals. A 29 kDa protein isolated from detergent soluble antigen of S. digitata showed maximum inhibition of cell mediated immune response. The heat inactivated 29 kDa protein was found to be devoid of property of suppression of immune response in the host. Histological study of spleen of BALB/C mice immunized with 29 kDa protein showed changes in regions of spleen such as follicle, trabeculae, capsule, reticuloendothelial cells and eosinophils. The 29 kDa protein, the most reactive of the detergent soluble proteins produced partial suppression of immune response, thereby contributing to the factors responsible for the survival of filarial parasites in hosts.

Antigenic analysis of purified surface antigens of filarial nematode Setaria digitata.

The surface antigens of S. digitata were isolated by treatment with Triton X-100. In non SDS-PAGE the surface antigen preparation resolved into more than 6 protein bands. Electroelution of gel slices corresponding to the protein bands with relative mobilities 0.09, 0.32, 0.41, 0.53, 0.61 and 0.76 gave 6 purified surface antigen fractions (SAF). Analysis of SAFs by SDS-PAGE showed that the proteins with molecular weights 17, 29 and 36 KD were the three major polypeptides and different combination of these gave rise to the 6 native surface proteins. The 29 KD protein existed as a monomer and as cross-linked with the 17 and 36 KD proteins. All surface antigen fractions showed antigenicity, where as 29 KD protein remained as a high avidity surface antigen.

Changes in the level of biogenic amines in experimentally infected and DEC treated proxy host mice.

The levels of biogenic amines, viz., epinephrine, histamine and dopamine were significantly altered in the blood and brain of the proxy host mice which were infected with the mf of Setaria digitata, a filarial parasite. When DEC, the drug of choice was administered to the infected mice, serotonine level was enhanced while the histamine level was decreased. The results were similar in normal mice which were given DEC.

In vitro release of biologically active materials from the bovine filarial parasite Setaria digitata.

Release of macromolecules by S. digitata, in 9 different media under in vitro condition have been studied. A direct relationship between microfilariae (mf) release and associated folin positive materials was seen in majority of the cases. High activities of hydrolytic enzymes such as protease, collagenase, alkaline phosphatase and lipase were detected in the excretary-secretary products and worm preparations. Activity of collagenase could not be detected in the male worm under experimental conditions.

Isolation and analysis of surface antigens of filarial nematode Setaria digitata.

Surface antigens of adult filarial parasite S. digitata was isolated by employing techniques from manual dissection to treatment with detergents. Among the surface antigen preparations (SAPs), the activities of marker enzymes such as alkaline phosphatase, adenosine triphosphatase and 5' nucleotidase were higher with that isolated by triton X-100 technique (SAP2). On SDS-PAGE, the SAP2 has three major proteins with molecular weights 17, 29 and 36 KD which were consistent with the PBS soluble cuticular proteins (SAP1). Besides these, few other minor protein bands were also observed with the other SAPs. All SAPs were antigenic and showed positive reaction against antiserum to SAP2, and the results confirmed the SAP2 as a better preparation. The release of 29 KD surface protein during in vitro culture of adult parasite and its cross-reactivity with antiserum to surface antigens revealed the possible natural shedding of surface molecules into the host system.

Excretory/secretory antigens from a bovine filarial parasite cross react with human antifilarial antibodies.

Certain excretory/secretory proteins released by adult females of the bovine filarial parasite, Setaria digitata, along with the release of microfilariae when chromatographically analysed has three major protein fractions of molecular weights 70 kD (ESF1), 16.5 kD (ESF2) and 11 kD (ESF3). Of these ESF2 and ESF3 cross reacted with antibodies from Wuchereria bancrofti infected humans. ESF2 was more specific and accurate in detecting human filarial infection. Similar proteins secreted by human filarial parasites could be targets for combating the disease by cure or control.

Enzymes of PEP-succinate pathway in Setaria cervi and effect of anthelmintic drugs.

Localization of different enzymes of PEP-succinate pathway has been done in Setaria cervi, a bovine filarial worm. Succinate dehydrogenase and fumarate reductase were localized in mitochondria rich particulate fraction while all other enzymes were cytosolic. The in vitro effect of certain antifilarial/anthelmintic agents on these enzymes was also investigated. Sumarmin, at low concentration, could cause a marked inhibition of most of the enzymes of this pathway. Centperazine, an antifilarial drug being developed by CDRI showed significant inhibitory action on pyruvate kinase, lactate dehydrogenase, fumarase and succinate dehydrogenase while CDRI compound 72/70 showed significant inhibition of PEP-carboxykinase activity. Diethylcarbamazine and levamisole, however, were found to be more or less ineffective at lower concentrations against all the enzymes of this pathway.

Morphological studies on the larval stages of three species of Setaria and Dirofilaria repens.

This paper reports for the first time the morphology of larval stages of Setaria labiato-papillosa. The infective larvae of this species had two circles of small papillae on the cephalic end, 4 papillae for outer circle and 6 for inner circle. The caudal end of S. labiato-papillosa is in digital form with 3 transversally arranged papillae. There are 2 circles of small papillae on the cephalic end of S. leichungwingi and S. equina, 4 for each circle; the caudal terminal of the former species is willow-shaped with 3 pearl-like papillae, and that of the latter is conical shaped with 1 bulbed papilla, 2 slightly protruded papillae at sub-terminal. The anal ratios of all the above 3 species are below 3. Morphology of larval stages of Dirofilaria repens was also primarily described in China. The 3 bulbed caudal papillae of the infective larvae are closely arranged, and the anal ratio being less than 2. A key to infective larvae of 8 species of filaria was worked out according to relevant literature and the present study.

Effect of anthelmintics and phenothiazines on adenosine 5'-triphosphatases of filarial parasite Setaria cervi.

S. cervi showed particulate bound Ca2+ ATPase and Na+,K(+)-ATPase activities while Mg2+ ATPase was detected in traces. ATPase of S. cervi was also differentiated from the nonspecific p-nitrophenyl phosphatase activity. Female parasite and microfilariae exhibited higher Ca2+ ATPase and Na+,K(+)-ATPase activities than the male adults and the enzyme Na+,K(+)-ATPase was mainly concentrated in the gastrointestinal tract of the filarial parasite. Na+,K(+)-ATPase of the filariid was ouabain-sensitive while Ca2(+)-ATPase activity was regulated by concentration of Ca2+ ions and inhibited by EGTA. Phenothiazines, viz. trifluoperazine, promethazine and chlorpromazine caused significant inhibition of Ca2+ ATPase and Na+,K(+)-ATPase. Diethylcarbamazine was a potent inhibitor of these ATPases. Mebendazole, levamisole and centperazine also caused significant inhibition of the ATPases indicating this enzyme system as a common target for the action of anthelmintic drugs.

Excretory secretory antigens of filarial parasite Setaria digitata.

Excretory Secretory (ES) material isolated from the culture fluid of S. digitata was highly antigenic. Neither oesophagus nor excretory cells and excretory pore of the parasite showed reasonable fluorescence with ES antisera. However, the uterine tissue and the egg showed strong fluorescence. The egg showed fluorescence mainly in the space between embryo and egg membrane (amniotic fluid). The amniotic fluid was highly antigenic and appears to be the most important source of ES material released by the filarial parasites.

Cuticle specific antigens from filarial parasite Setaria digitata.

A fairly clean antigenic cuticle was isolated from the S. digitata by dissection. Crossed immunoelectrophoresis of cuticular antigens against rabbit antiserum to cuticular antigens gave 30 anodic and 5 cathodic precipitin arcs. The cuticle antiserum cross reacted with muscle, uterus and pseudocoelomic fluid. When the antiserum was absorbed individually with these cross reacting somatic preparations, analysis against cuticle antigens gave only a limited number of precipitin arcs. But the results are clear enough to indicate the presence of cuticle specific antigens. As the cuticle of the parasite is in contact with the host system, an antigenic preparation from it may prove a useful tool for the detection of filariasis.

Somatic antigens from male and female adults of Setaria cervi: immune reactions in guinea pigs

Los antígenos de Setaria cervi hembra son más eficaces que los de macho para evitar el desarrollo de microfilaremia en cabayos (10 parásitos por individuo). Con dosis altas (2ml 500 µl) se obtuvo resistencia significativa a partir de antígenos de parásitos machos (52% de protección) hembras (62%). Los antígenos de hembra tambíen protegieron (40% con dosis bajas (2ml 50 µ/ml)

Effect of diethylcarbamazine on Setaria cervi in vitro.

Diethylcarbamazine (DEC) produced an initial stimulation followed by depression of the movements of the intact worm and nerve-muscle preparation of Setaria cervi. The effective concentration of DEC was reduced to one hundredth in the nerve-muscle preparation as compared to the whole worm, suggesting that the cuticular barrier is highly effective in preventing the penetration of the drugs. The depressant effect of DEC was concentration dependent and was not reversed even after repeated changes of the bath fluid. The worms consumed 7.7 mg +/- 0.2 glucose/g wet weight/hr. The consumption of glucose was directly proportional to its motor activity; it increased during the stimulant phase with low doses of DEC and decreased during the depressant phase.