Humoral immune responses induced by Kudoa sp. (Myxosporea: Multivalvulida) in BALB/c mice: oral administration, immunization and cross-reactions with Myxobolus aeglefini (Myxosporea: Bivalvulida)

Myxozoans and Our Dinner Table: Pathogenicity Studies of Myxobolus honghuensis (Myxosporea: Bivalvulida) Using a Suckling Mice Model

Myxobolus honghuensis parasitizes the pharynx of the allogynogenetic gibel carp Carassius auratus gibelio (Bloch), an economically important food fish with large consumption rates in China. The fact that it is hard to detect the cysts formed by M. honghuensis without euthanizing the fish and the spores can reach the consumers has prompted us to investigate the effect of M. honghuensis on conventional, immunocompetent BALB/c suckling mice, in order to consider the possible pathological effects in general immunocompetent consumers by the ingestion of Myxobolus-infected fish. BALB/c suckling mice were inoculated with serial dilutions of the spore suspension and then hematological and histological studies were performed. Tests of suckling mice showed no statistically difference of fluid accumulation ratio between mice inoculated with 1.65 × 10(6) M. honghuensis spores and negative control after 8-h incubation. Spores did not disrupt intestinal histology, and no abnormal bowel movements were observed within 20 h postinoculation. No anomalous hematology parameters were documented. These results, taken together, reveal that M. honghuensis spores do not cause pathology (diarrhea and elevated fluid accumulation) in BALB/c suckling mice. However, an extrapolation is not currently feasible because of lack of a highly quantifiable risk extrapolation model, inaccessibility to data for the effect of M. honghuensis on humans, and lack of consideration of the immunosuppressed population. Our study extends the results of the effect of myxozoan on suckling mice and serves as baseline for future experiment using the same model in evaluating the myxozoan-caused foodborne disease.

Immunohistochemical characterization of polyclonal antibodies against Enteromyxum leei and Enteromyxum scophthalmi (Myxozoa: Myxosporea), intestinal parasites of fish

The enteric myxozoan parasites Enteromyxum leei (Diamant, Lom et Dyková) and Enteromyxum scophthalmi Palenzuela, Redondo et Álvarez-Pellitero are responsible for high weight loss in infected fish, which leads to subchronic disease and low mortality rates in gilthead sea bream (GSB), Sparus aurata L., and to high mortality rates in turbot, Psetta maxima (L.). The detection of initial parasite stages in histological sections is particularly difficult, but can be simplified by means of specific antibodies. Rabbit polyclonal antibodies (pAbs) were raised against E. scophthalmi and E. leei, and direct enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry were used to characterize their sensitivity and specificity. Both pAbs were adsorbed (apAb) with non-infected intestines to avoid non-specific labelling of fish tissues and to improve their specificity. The highest titre obtained in ELISA was 1: 32 000 for apAb-Eleei and 1:16 000 for apAb-Escoph. Working dilutions in immunohistochemistry were 1:1000 for apAb-Eleei and 1:8000 for apAb-Escoph. Both apAbs labelled proliferative and sporogonic stages with high specificity. apAb-Escoph was very specific, whereas apAb-Eleei cross-reacted with Sphaerospora dicentrarchi Sitjà-Bobadilla et Álvarez-Pellitero and Sphaerospora testicularis Sitjà-Bobadilla et Álvarez-Pellitero, suggesting the presence of shared antigens. These pAbs stand as new tools for antigenic characterization and the diagnosis of both Enteromyxum species.

The effect of anti-Anisakis simplexantibody levels on C3 and C4 complement components in human sera

Previously, anin vitroeffect was observed on the complement system not only of the excretory-secretory products but also of somatic antigens from L3Anisakis simplexlarvae. In the present work the effect of anti-A. simplexspecific antibodies on C3 and C4 levels in human sera was investigated. Up to 309 samples of sera were tested to determine levels of C3 and C4 and anti-A. simplexantibodies, including immunoglobulins IgG, IgM, IgA and IgE. Significant differences were observed between levels of C3 and C4 and all immunoglobulins except for IgE. In the case of immunoglobulins, the probability that an anti-A. simplexpositive subject has a C3 deficiency was 3.8 times higher than a subject without specific antibodies. In conclusion, an association between elevated levels of anti-A. simplexantibodies and C3 and C4 deficiency was demonstrated.

Differential effect of appendectomy and tonsillectomy on anti-Kudoa sp. antibodies in patients with MALTectomy

We found an association between tonsillectomized patients and subsequent appendicitis. We also observed that MALTectomy significantly decreased secretory IgA levels in serum of patients, being this decrease more pronounced when both operations (tonsillectomy and appendectomy) had been performed. The elevated humoral responses detected previously by us in BALB/c mice immunized with Kudoa sp. pseudocyst extracts and the high IgG1 and IgE levels induced by the oral administration of Kudoa sp. pseudocysts to BALB/c mice showed the possible immunopathological effects in man from the ingestion of Kudoa sp. infected fish. We use the ELISA method to investigate the possible relationship between MALTectomy (tonsillectomy and appendectomy) and specific antibody levels to Kudoa sp. Both anti-Kudoa sp. specific antibody levels and the number of patients that recognized Kudoa sp. antigens were greater in tonsillectomy patients when compared to the control and the other studied groups (appendectomized and appendectomized+tonsillectomies patients). Tonsillectomy was associated to a switch in the class of immunoglobulins involved in these responses and these responses may be abrogated by appendectomy. Tonsils and appendix may respond in different ways to Kudoa sp. antigens and these different reactions may be involved in some immunopathological reactions.

Seroprevalence of anti-Gymnorhynchus gigas (Trypanorhyncha, Gymnorhynchidae) antibodies in a Spanish population

The somatic products released from ingested larvae of Gymnorhynchus gigas parasitizing fish induce a Th2 response capable of causing allergic disorders. The objective of the present work was to evaluate the prevalence of anti-Gymnorhynchus gigas antibodies in a Spanish population and established a possible relationship with fish consumption habits. We studied 305 residents in Madrid, with neither clinical symptoms suggestive of gastrointestinal or allergic disorders, nor pathologies related to ingestion of fish that could cause disease. Specific antibody levels were measured by ELISA: 11.8%, 20%, 15.7%, 21%, and 7.5% of the total studied sera were IgA, Ig's, IgG, IgM, and IgE positive, respectively. Seropositivity was not more prevalent among fresh fish consumers and did not increase with frequency of fish consumption. IgE values were lower in the group that never ingested smoked fish. Anti-G. gigas antibody levels were higher in the group that reported frequent consumption of marinated fish. The use of cooking methods with the least heating efficacy (frying, or frying in batter, and microwaving) did not affect seropositivity percentages among consumers. Infection with live plerocercoids is not necessary for seropositivity, and the antibody production, in this case, is due to the absorption of antigens from the parasite following the digestion process. The human health risks of allergic reactions due to parasite antigens remain active after freezing the fish.

Allergenic activity of Molicola horridus (Cestoda, Trypanorhyncha), a cosmopolitan fish parasite, in a mouse model

The cestode Molicola horridus is a muscle parasite of teleost fish. The ability of molecules present in this parasite to induce allergic response is not known yet. Since fish-borne parasitic allergens can induce allergic manifestations even when the parasitized fish is well cooked, the knowledge of potential allergens present in food is important in order to provide a save products for consumers. The aim of the study was to determine the allergenic potential of the components present in the crude larval extract (CLE) of M. horridus. Two mouse models were exposed to the CLE: adult BALB/c mice that were intraperitoneally (i.p.) immunized and newborn BALB/c mice that were orally exposed. Specific antibody levels in serum and faeces were measured by ELISA. The cellular immune response was determined by proliferation assay of splenocytes from sensitized mice. The protein profile of CLE was analysed by SDS-PAGE and western blot. In adult mice, specific IgG and IgA were detected in sera and faeces, whereas specific IgE were detected in sera only. In newborn mice, specific IgG were detected in sera and a low level of IgA was detected in faeces. SDS-PAGE revealed the CLE protein profile, with most of the proteins running from 15 to 50kDa. Specific IgG recognized mainly the 26 and 75kDa proteins and a molecular complex below 100kDa by immunoblot. Specific IgE recognized the same 26kDa protein as IgG did, and, with less intensity, another protein at 30kDa. Splenocytes from CLE-immunized mice proliferated when stimulated with CLE in a dose-dependent manner. The crude larval extract from M. horridus has potential allergenic molecules which can represent a risk for fish consumers.

Seroprevalence of anti-Kudoa sp. (Myxosporea: Multivalvulida) antibodies in a Spanish population

A majority of Kudoa species infect the somatic muscle of fish establishing cysts. Because there is no effective method to detect infected fish without destroying them, these parasitised fish reach the consumer. The elevated humoral responses detected previously by us in BALB/c mice immunised with Kudoa sp. pseudocyst extracts and the high IgG1 and IgE levels induced by the oral administration of Kudoa pseudocysts to BALB/c mice showed the possible immunopathological effects in man from the ingestion of Kudoa-infected fish. In this work, we investigated the seroprevalence of anti-Kudoa sp. antibodies in a Spanish healthy population and the possible association between the manifestation of allergic reactions after fish consumption and the humoral responses to Kudoa sp. antigens. Specific anti-Kudoa sp. antibody levels in sera of patients diagnosed with several digestive pathologies were also determined, studying their possible association with the alteration of analytic parameters in these patients.