Immunoglobulin isotype response of Fasciola spp. infected sheep and cattle to defined Fasciola spp. antigens

• Main Author: Phiri, Isaac Khozozo
• Published: University of Edinburgh 1997
• Subjects: 636.089
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653375

Fasciolosis is a liver fluke disease, caused by <I>Fasciola hepatica </I>in temperate regions and high altitude areas of the tropics and subtropics and by <I>Fasciola gigantica, </I>which is restricted to the tropics and subtropics. Liver flukes have a wide range of definitive hosts, including man and, in particular, domestic ruminants, but the various hosts are known to differ greatly in their resistance to infection with these parasites. For example sheep are considered susceptible to challenge infection while cattle develop resistance. <I>F. hepatica </I>secretes the enzyme cathepsin-L1 protease (Fh-cathepsin) which has a molecular weight (MWt) of 27 kDa. It is considered to have a functional role in parasite evasion of the host immune response, through cleavage of host immunoglobulin. The enzyme, glutathione s-transferase (GST) which is of 27.8-29 kDa MWt, is also secreted by <I>F. hepatica </I>(Fh-GST) and is thought to be involved in the detoxification of exogenous (xenobiotic) and endogenous derived toxic compounds. Both enzymes form part of the fluke excretory/secretory (E/S) products and are of additional interest in that they are considered as vaccine candidates against fasciolosis. This study investigated the immunoglobulin isotype responses of sheep and cattle, chronically infected with <I>F. hepatica </I>and <I>F. gigantica, </I>to defined fluke antigens (<I>F. hepatica </I>E/S products (Fh-E/S) or <I>F. gigantica </I>E/S products (Fg-E/S), Fh-cathepsin and Fh-GST). It was decided to study the immune response in chronically infected animals since immunity is considered to play a potentially more important role in chronic infection than in acute infection, which is characterised by the death of the animal through anaemia and blood loss caused by the migrating flukes. Serum and faecal samples were collected weekly while the severity of the infections were defined using clinical, parasitological, haematological, biochemical and pathological parameters. Serum and faecal antibody (total Ig, IgG<SUB>1</SUB>, IgM, IgG<SUB>2</SUB> and IgA) responses to 24-48 hour Fh-E/S, adult Fh-cathepsin and adult Fh-GST were determined by indirect Enzyme-linked Immunosorbent Assay (ELISA). The antigen recognition profile of the <I>Fasciola </I>spp. infected sheep and cattle to Fh-E/S and Fg-E/S was examined by sequential Western blotting.