Vaccine potential of recombinant saposin-like protein 2 against Fasciolosis gigantica in mice.
Saposin-like protein 2 (SAP-2) is a protein that adult of Fasciola spp. use to lyse plasma membrane of red blood cells, so that their contents can be digested by proteases for the parasites' nutrients. Thus SAP-2 is a plausible target for vaccination against these parasites. Recombinant Fasciola gigantica saposin-like protein 2 (rFgSAP-2) was expressed in Escherichia coli BL21 (DE3). A vaccination was performed in ICR mice (n=10) by subcutaneous injection with 50μg of rFgSAP-2 combined with Freund's adjuvant. At 2 weeks after the second boost, mice were infected with 30 F. gigantica metacercariae by oral route. The percentages of protection of rFgSAP-2 vaccine against F. gigantica were estimated to be 76.4-78.5% when compared with non vaccinated-infected and adjuvant-infected controls, respectively. The antibodies in immune sera of vaccinated mice were shown by immuno-blotting to react with native FgSAP-2 in the extract of 2- and 4-week-old juvenile parasites. By determining the levels of IgG1 and IgG2a in the immune sera, which are indicative of Th2 and Th1 immune responses, it was found that both Th1 and Th2 humoral immune response were significantly increased in rFgSAP-2 immunized group compared with the control groups, with higher levels of Th2 (IgG1) than Th1 (IgG2a). The levels of serum aspartate aminotransferase (AST) and alanine transaminase (ALT) in rFgSAP-2-immunized group showed no significant difference from those of the non-immunized and infected group, indicating that early juvenile parasites induced liver parenchyma damage, even though the numbers of worm recoveries were significantly different. This study indicates that rFgSAP-2 has a high potential as a vaccine candidate against F. gigantica in mice, and this potential will be tested in larger economic animals.
Department of Pathobiology, Faculty of Science, Mahidol University, Rama 6 Road, Ratchathewi, Bangkok 10400, Thailand; Faculty of Allied Health Sciences, Burapha University, Long-Hard Bangsaen Road, Saen Sook Sub-district, Mueang District, Chonburi 20131, Thailand. Electronic address: earn_patho@hotmail.com.
Pornanan
P
Kueakhai
Narin
N
Changklungmoa
Suda
S
Riengrojpitak
Pannigan
P
Chaichanasak
Krai
K
Meemon
Kulathida
K
Chaithirayanon
Pathanin
P
Chantree
Veerawat
V
Sansri
Tadashi
T
Itagaki
Prasert
P
Sobhon
D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D000947:Antigens, Helminth / Q000235:genetics / Q000276:immunology*; D004195:Disease Models, Animal; D004926:Escherichia coli / Q000235:genetics; D005209:Fasciola / Q000276:immunology*; D005211:Fascioliasis / Q000276:immunology / Q000517:prevention & control*; D005620:Freund's Adjuvant / Q000008:administration & dosage; D015870:Gene Expression; D015801:Helminth Proteins / Q000235:genetics / Q000276:immunology*; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D049231:Saposins / Q000235:genetics / Q000276:immunology*; D014611:Vaccination / Q000379:methods; D014612:Vaccines / Q000008:administration & dosage* / Q000276:immunology*
D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D015801:Helminth Proteins; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D049231:Saposins; D014612:Vaccines; D005620:Freund's Adjuvant
Fasciola gigantica; Mice; Protection; Saposin-like protein 2; Vaccine