Antibody responses to fluke cysteine proteinases in Paragonimus- and Fasciola-infected rats

Abstract

IgG and IgM antibody responses to fluke cysteine proteinases in Paragonimus ohirai- and Fasciola sp.-infected rats were followed by means of cystatin capture ELISA using fluke excretory-secretory products for 10 weeks after infection. The specific IgG antibodies were detectable at week 2 postinfection in all P. ohirai-infected and some Fasciola-infected rats. Levels of specific IgG antibodies increased rapidly between week 2 and 6, and slightly thereafter, in both infected groups. From week 3, specific IgG antibody levels were higher in Fasciola-infected than P. ohirai-infected rats. Sera from infected rats did not react with heterologous cysteine proteinases throughout the infection periods. In both infected groups, the kinetic patterns of specific IgM antibody responses were similar to those of specific IgG antibody responses although the ELISA levels of the IgM antibody responses were much lower. In abnormal infections with P. ohirai metacercariae x-irradiated at 2 krad, the specific IgG antibodies were detectable at week 2 postinfection with similar ELISA values to normal P. ohirai infection, but thereafter increased little. In infections with P. westermani, for which the rat is not a suitable host, even stunted worms induced a comparable specific IgG antibody response, although the response was lower than in normal infections with P. ohirai. These results indicate that cystatin capture ELISA can distinguish clearly between Paragonimus and Fasciola infections which show immunodiagnostic cross-reactivity and is useful even in the early stages of the infection and in the infection of unsuitable hosts.

Structural and Immunological Characteristics of a 28-Kilodalton Cruzipain-Like Cysteine Protease ofParagonimus westermaniExpressed in the Definitive Host Stage

“…The successful use of P. westermani cysteine proteases as diagnostic antigens has been documented with the use of partially purified enzymes or the application of cystatin-capture ELISA (15)(16)(17). However, its application is limited not only by the availability of parasite materials but also by the difficulties with the purification of the specific antigens.…”

“…The mechanism of cross-reactivity due either to common epitopes shared by different trematode parasites or to other host factors possibly associated with major histocompatibility complex type II molecules awaits further elucidation to strengthen the diagnostic reliability for paragonimiasis. However, Pw28CCP seems to be an important antigen since its diagnostic value was comparable to those of mixed or partially purified cysteine protease or other protein antigens that have been used in antibody assays (15)(16)(17)26). This study confirmed the usefulness of P. westermani cysteine protease as a potent diagnostic antigen.…”

Cystatin Capture Enzyme-Linked Immunosorbent Assay for Serodiagnosis of Human Clonorchiasis and Profile of Captured Antigenic Protein ofClonorchis sinensis

“…This finding indicates that human clonorchiasis can be serodiagnosed by cystatin capture ELISA as early as 3 weeks after the infection. A similar pattern was seen in experimental mice infected with Paragonimus, Fasciola, or Schistosoma, in which IgG antibodies specific for cysteine proteinases were detected in the animals at week 2 and in which IgG antibody levels increased rapidly between 3 and 5 weeks after infection (20). One might speculate that the delay in the appearance of C. sinensis-specific antibodies compared to the times of appearance of antibodies specific for tissue-invading trematodes reflects an outcome derived from the luminal parasitism in the biliary tract without migration through tissue and, consequently, less effective antigen presentation through the mucosae of the biliary and intestinal tracts.…”

Effect of fasciolicides on the antigenaemia in sheep naturally infected with Fasciola hepatica

“…In the acute stage, immature worms migrate through the intestine, peritoneum and liver parenchyma. The chronic stage begins when¯ukes reach the bile ducts and attain sexual maturity (Ikeda 1998;O'Neill et al 2000). The signi®cance of the economic losses led to the development and introduction of a wide variety of fasciolicides.…”