PROTEASE ACTIVITY OF EXCRETORY/SECRETORY RELEASED BY INVASIVE STAGE OF Ascaridia galli

Darmawi1*, Ummu Balqis2, Risa Tiuria3, Maggy T. Suhartono3, Retno D. Soejoedono3, Bambang P. Priosoerjanto3, Fachriyan H. Pasaribu3, and Muhammad Hambal4
1. Laboratory of Microbiology, Veterinary Faculty of Syiah Kuala University
2. Laboratory of Pathology, Veterinary Faculty of Syiah Kuala University
3. Graduate School Teaching Staff, Bogor Agriculture Institute
4. Laboratory of Parasitology, Veterinary Faculty of Syiah Kuala University
Correspondence to: Darmawi, phone: (0251)629039 or 08128411352,
fax : (0251)421174, and e-mail address: d_darmawi@yahoo.com

ABSTRACT

Excretory/secretory (ES) released by Ascaridia galli can modulate immune response mechanism and cause inflammatory in the small intestine of poultry. The mechanisms that underlie tissue damage and invasion by the invasive stages (L3) of the parasitic nematode A. galli are poorly understood, but involvement of as yet uncharacterized protease has been suggested. Here, we employed casein assays to examine protease activity in ES product released by L3 of A. galli. A. galli L3 recovered from intestines of 100 head chickens 7 days after each oesophagus inoculation with 6000 L2 were cultured (5 – 10 ml-1) in flasks containing RPMI 1640 media, pH 6.8, without phenol red and suplemented with 100 units ml-1 penicillin G, 100 μg ml-1 streptomycin, 5 μg ml-1 gentamycin, and 0.25 μg ml-1 kanamycin. Cultures were incubated at 370C in 5% CO2 and ES product of L3 released in culture was collected after 3 days. The protease activity was assayed against casein. The amount of degradation was determined from the absorbance at 578 nm. One unit of enzyme activity was defined as the amount of enzyme necessary to elaborate 1 μg of tyrosine from casein in 1 ml of reaction volume per min. The result showed that enzyme activity and protease specific activity of ES product released by L3 of A. galli were 0.5652 x 10-2 IU/ml and 0.575 x 10-3 IU/mg, respectively. The result indicate that the infection process of a number of organisms, including some nematodes, depends on protease. A. galli may likewise utilize protease to facilitate larval invasion, migration within the host tissue, and modulation of host immune response mechanisms.

KEY WORDS: Ascaridia galli, protease, excretory/secretory, nematode