Molecular cloning and expression profiles of chicken NK-lysin during Eimeria infections
Yeong H. Hong*, Hyun S.
Lillehoj#,
Rami A. Dalloul, Kate B. Miska, Wenbin Tuo, and Sung H. Lee
Animal Parasitic Diseases Laboratory, Animal and Natural Resources Institute,
USDA-ARS, Beltsville, MD 20705, USA
ABSTRACT
NK-lysin is known to have antibacterial and antitumor activities and is
expressed by NK cells as well as T-lymphocytes. In a previous report, the contig
171 (NK-lysin-like sequence), composed of 87 ESTs, occurred with the highest
prevalence in an Eimeria-induced intestinal cDNA library. This study was
conducted to clone, express, and characterize contig 171 as the chicken NK-lysin,
which consists of an 868 bp DNA sequence and an open reading frame of 140 amino
acids with a predicted molecular mass of 15.2 kDa. Comparison of deduced amino
acid sequences showed less than 20% identity to granulysin and other mammalian
NK-lysins. When infected with E. maxima, chicken total intraepithelial
lymphocytes (IELs), CD4+ and CD8+ IELs showed higher expression levels of
NK-lysin mRNA than CD8- IELs as quantified by real-time PCR. Upon infections
with three Eimeria species, chicken NK-lysin RNA expression level normalized to
GAPDH exhibited differential and interesting patterns. Further, chicken NK-lysin
was expressed into COS-7 cells and its antitumor activity was demonstrated in
killing LSCC-RP9 macrophage transformed cells. Also, chicken NK-lysin showed
sequence similarity to other mammalian cDNA with cytotoxic activity to tumor
cells. In these studies, we cloned and characterized chicken NK-lysin and
studied its expression patterns in mRNA of Eimeria-infected birds. As in other
animals, chicken NK-lysin may play an important role in antimicrobial defenses
against enteric pathogens such as Eimeria, especially at the early stages of
such infections.
*Presenting Author
#Corresponding Author
E-mail: hlilleho@anri.barc.usda.gov