Biochemical characterization and vaccine potential of a heme-binding glutathione transferase from the adult hookworm Ancylostoma caninum.
We report the cloning and expression of Ac-GST-1, a novel glutathione S-transferase from the adult hookworm Ancylostoma caninum, and its possible role in parasite blood feeding and as a vaccine target. The predicted Ac-GST-1 open reading frame contains 207 amino acids (mass, 24 kDa) and exhibited up to 65% amino acid identity with other nematode GSTs. mRNA encoding Ac-GST-1 was detected in adults, eggs, and larval stages, but the protein was detected only in adult hookworm somatic extracts and excretory/secretory products. Using antiserum to the recombinant protein, Ac-GST-1 was immunolocalized to the parasite hypodermis and muscle tissue and weakly to the intestine. Recombinant Ac-GST-1 was enzymatically active, as determined by conjugation of glutathione to a model substrate, and exhibited a novel high-affinity binding site for hematin. The possible role of Ac-GST-1 in parasite heme detoxification during hemoglobin digestion or heme uptake prompted interest in evaluating it as a potential vaccine antigen. Vaccination of dogs with Ac-GST-1 resulted in a 39.4% reduction in the mean worm burden and 32.3% reduction in egg counts compared to control dogs following larval challenge, although the reductions were not statistically significant. However, hamsters vaccinated with Ac-GST-1 exhibited statistically significant worm reduction (53.7%) following challenge with heterologous Necator americanus larvae. These studies suggest that Ac-GST-1 is a possible drug and vaccine target for hookworm infection.
Zhan
Bin
B
Department of Microbiology and Tropical Medicine, The George Washington University, Washington, DC 20037, USA.
Liu
Sen
S
Perally
Samirah
S
Xue
Jian
J
Fujiwara
Ricardo
R
Brophy
Peter
P
Xiao
Shuhua
S
Liu
Yueyuan
Y
Feng
Jianjun
J
Williamson
Angela
A
Wang
Yan
Y
Bueno
Lilian L
LL
Mendez
Susana
S
Goud
Gaddam
G
Bethony
Jeffrey M
JM
Hawdon
John M
JM
Loukas
Alex
A
Jones
Karen
K
Hotez
Peter J
PJ
D000595:Amino Acid Sequence; D000722:Ancylostoma / Q000201:enzymology / Q000276:immunology*; D000724:Ancylostomiasis / Q000517:prevention & control*; D000818:Animals; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics / Q000276:immunology*; D003001:Cloning, Molecular; D006224:Cricetinae; D004285:Dogs; D005982:Glutathione Transferase / Q000032:analysis / Q000235:genetics / Q000276:immunology*; D000081062:Heme-Binding Proteins; D006420:Hemeproteins / Q000032:analysis / Q000235:genetics / Q000276:immunology*; D007814:Larva / Q000201:enzymology; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D014612:Vaccines / Q000235:genetics / Q000276:immunology
D002352:Carrier Proteins; D000081062:Heme-Binding Proteins; D006420:Hemeproteins; D012333:RNA, Messenger; D014612:Vaccines; D005982:Glutathione Transferase