Humoral immune responses induced by Gymnorhynchus gigas extracts in BALB/c mice

A Study on the Pathological Effects of Trypanorhyncha Cestodes in Dusky Groupers Epinephelus marginatus from the Canary Islands

Simple Summary

Trypanorhyncha are common parasites of marine fish. Despite numerous studies detailing their biology, knowledge on the effects caused by these parasites in fish tissues is still limited. Dusky groupers are keystone species, necessary for the preservation of several marine ecosystems. Considering their vulnerable state of conservation and the efforts being made to culture them, identification of the effects caused by Trypanorhyncha is vital. Here, we have assessed the prevalence of Trypanorhyncha in dusky groupers from the Canary Islands and the associated pathological changes. Of the 28 fish examined, 27 presented trypanorhynch larvae. Macroscopically, in the abdominal cavity, there were numerous larvae-filled cysts and nodules embedded in abundant fibrosis, hindering the separation of the organs. Microscopically, in the peritoneum, stomach and intestine, there were numerous degenerated parasitic cysts and extensive deposition of fibrous connective tissue with minimal inflammatory responses. This study shows that Trypanorhyncha are common parasites of adult dusky groupers from the Canary Islands. Even though the immune system appears to isolate and eliminate the parasites, extensive fibrosis may have a detrimental impact on fish health when adjacent organs are compressed and their functions impaired.

Abstract

Trypanorhyncha are cestodes commonly infecting marine fish. Numerous studies have detailed the biology of Trypanorhyncha species, but information on the pathological changes produced by these parasites is limited. Dusky groupers are keystone species necessary for the preservation of several marine ecosystems. Considering their vulnerable state of conservation and the efforts being made to culture them, identification of the effects caused by Trypanorhyncha is vital. Here, we aimed to determine the prevalence and pathological changes produced by Trypanorhyncha in dusky groupers from the Canary Islands. The prevalence of trypanorhynch plerocerci was 96%. Grossly, in the abdominal cavity, there were numerous larvae-filled cysts and nodules. These were embedded in abundant fibrosis, producing visceral adhesions. Histologically, affecting the peritoneum, stomach, and intestine there were numerous degenerated encysted plerocerci and extensive deposition of mature connective tissue. These findings indicate that Trypanorhyncha is highly prevalent in adult dusky groupers from the Canary Islands, producing a progressive and chronic response. Furthermore, fish immune system appears to attempt to eliminate the parasites through fibrous encapsulation. Nonetheless, extensive fibrosis may have a detrimental impact on fish health when adjacent cells or tissues are compressed and their functions impaired.

Trypanorhynch cestodes parasitizing Mugil liza (Mugiliformes: Mugilidae) commercialized in the state of Rio de Janeiro, Brazil

The aim of the present study was to identify, through morphological and morphometric analyses, the species of trypanorhynch cestodes found as plerocerci in the intestinal serosa of Mugil liza and to determine their parasitic indices. One hundred and fifty specimens of this mullet collected off the coast of the state of Rio de Janeiro were necropsied and the trypanorhynch cestodes found were fixed and preserved as whole mounts for morphological analysis. The plerocerci were identified as Callitetrarhynchus gracilis and Pterobothrium crassicole, both with a prevalence of 0.67%, an intensity of 1 and abundance of 0.0067, in single infections. This is the first record of a trypanorhynch cestode parasitizing M. liza in Brazil. Although the parasitic indexes were low, from a hygienic-sanitary perspective the plerocerci of these species are visible to the naked eye, and thus can disgust consumers and make marketing the fish unfeasible.

Callitetrarhynchus gracilis (Rudolphi, 1819) Pintner, 1931 (Cestoda: Trypanorhyncha) parasitizing the musculature of Sardinella brasiliensis (Steindachner, 1879) (Actinopterygii) off the coast of the state of Rio de Janeiro, Brazil

Cestodes of the order Trypanorhyncha can frequently be found infecting the muscles of several marine fish species, and lead to a repugnant aspect of the fish and rejection by consumers. The Brazilian sardinella, Sardinella brasiliensis, occurs from the Gulf of Mexico and the Caribbean to northern Uruguay. In southeastern Brazil, fishing for the species is very intensive since it generates significant revenue as one of the most commonly consumed fish and an important element of the canned fish industry. The aims of the present study were to identify and report the occurrence of tiny cestodes (3 mm-6.6 mm) in the musculature of Brazilian sardinella that were purchased in the São Pedro fish market in the municipality of Niterói, state of Rio de Janeiro, Brazil. From October 2013 to November 2016, 75 specimens of S. brasiliensis were investigated. The trypanorhynch cestodes encountered were identified as plerocerci of Callitetrarhynchus gracilis using morphological, morphometric and molecular data. Parasitic indices were calculated, and the cestodes infection of the musculature of Brazilian sardinella had the following values: prevalence, 40%; mean intensity, 3.47; mean abundance, 1.39; and range of infection, 1-18, specimens. The presence of this trypanorhynch cestode in the musculature of Brazilian sardinella is an important indicator of fish hygiene.

Grillotia (Cestoda: Trypanorhyncha) plerocerci in an anglerfish (Lophius piscatorius) from the Tyrrhenian Sea

Trypanorhynch cestodes are common parasites of marine fish with complicated life cycles which have been suggested as model taxa to study the evolution of marine helminth parasites and their life cycles. Among the Trypanorhyncha, the genus Grillotia includes 18 valid species, of which only four have been found in Mediterranean fish hosts. Morphological, histopathological, and molecular data are presented on a massive Grillotia plerocercus infection in an anglerfish (Lophius piscatorius) from the Tyrrhenian Sea. BLAST analysis of the 28S rDNA sequences revealed 99% similarity between specimens here found and a G. (Bathygrillotia) rowei sequence available in GenBank with a total of six nucleotide site differences. A morphological study suggested that the Grillotia sp. here reported did not match important characters to those previously reported from the Mediterranean Sea. Taking in account these differences, we prefer to place these specimens within Grillotia sensu lato until more material is available for study including sequences from adult specimens of Grillotia spp. from the Mediterranean Sea.

Pterobothrium crassicolle parasitizing Paralichthys orbignyanus (Osteichthyes, Paralichthyidae) in Brazil

From September 2014 to November 2015, 30 Paralichthys orbignyanus specimens were obtained from Sepetiba Bay in the municipality of Rio de Janeiro, State of Rio de Janeiro, Brazil. The fishes were necropsied and cestode larvae were recovered from the abdominal cavity, mesentery, and serosas of the stomach, intestine, spleen, liver, kidney and gonads. Nineteen fish were parasitized by a total of 90 trypanorhynch plerocerci. Based on morphological characters, these were identified as Pterobothrium crassicolle. The parasitism indices for P. crassicolle on P. orbignyanus, were 63.3% for prevalence, 4.7 for mean intensity, 3 for mean abundance and 1 to 18 for range of infection. These parasites were studied due to their importance during fish sanitary inspection, if one considers the harm that the repulsive aspect of infected fish may cause to consumers. This is the first record of P. crassicolle plerocerci parasitizing P. orbignyanus.

Immunogenic activity of the fish tapeworm Pterobothrium heteracanthum (Trypanorhyncha: Pterobothriidae) in BALB/c mice

The aim of this study was to verify the immunogenicity of Pterobothrium heteracanthum (Cestoda: Trypanorhyncha) crude protein extract (PH-CPE) in BALB/c mice. The parasites were obtained from Micropogonias furnieri (Osteichthyes: Sciaenidae). Groups of six mice were each immunized with 10, 50 or 100 μg of PH-CPE, on days 0 and 35. Both specific IgG and IgE responses were developed after immunization. The immunoblot assay revealed that specific IgG recognizes PH-CPE proteins with two molecular weight ranges, 60-75 and 30-40 kDa, and that IgE recognizes larger proteins over 120 kDa. This appears to be the first report on the immunogenicity of metacestodes within the Pterobothriidae and that PH-CPE is a potential inducer of a specific IgE response.

Trypanorhyncha cestodes of hygienic-sanitary importance infecting flounders Paralichthys patagonicus Jordan, 1889 and Xystreurys rasile (Jordan, 1891) of the Neotropical region, Brazil

From February 2007 to July 2010, 27 specimens of Paralichthys patagonicus, and from September to December 2010, 30 specimens of Xystreurys rasile were purchased from fish markets in the municipalities of Cabo Frio and Rio de Janeiro, State of Rio de Janeiro, Brazil. The fishes were measured, necropsied, filleted, and further had their organs investigated. In P. patagonicus, 19 (70, 3 %) were parasitized with metacestodes of Trypanorhyncha species: Nybelinia erythraea, N. lingualis, Heteronybelinia nipponica, Pterobothrium crassicolle, Grillotia carvajalregorum, and Callitetrahynchus gracilis. In X. rasile, 17 (56, 6 %) were parasitized with metacestodes: N. erythraea, N. lingualis, H. nipponica, and G. carvajalregorum. The parasitological indices of prevalence, intensity, mean intensity, abundance, mean abundance, range of infection, and infection sites of each parasite species are presented. This is the first report of Trypanorhyncha cestodes parasitizing specimens of P. patagonicus and X. rasile. These cestodes were studied due to their importance during fish sanitary inspection, if one considers the harm that the repulsive aspect of infected meat causes to consumers.

Nematoides anisaquídeos e cestoides Trypanorhyncha de importância em saúde pública em Aluterus monoceros (Linnaeus, 1758) no Estado do Rio de Janeiro, Brasil

Entre maio e agosto de 2006, foram adquiridos 100 espécimes de peixe-porco, Aluterus monoceros em estabelecimentos de pescado nos municípios de Niterói e Rio de Janeiro. Os peixes foram medidos, necropsiados, filetados e seus órgãos analisados. Foram encontrados 16 peixes parasitados por larvas de nematoides anisaquídeos pertencentes às espécies Anisakis sp. e Contracaecum sp., com prevalência de 1 e 16%, intensidade média de 2 e 3,31 e abundância média de 0,02 e 0,53, respectivamente. Duas larvas de Anisakis sp. foram encontradas no mesentério de um peixe; e de Contracaecum sp. no fígado e mesentério, com amplitude de variação da intensidade de infecção de 1 a 9. Cinquenta e um peixes mostravam-se parasitados no fígado e mesentério por cestoides da ordem Trypanorhyncha. As espécies colhidas foram Floriceps saccatus e a Callitetrarhynchus speciosus, com a prevalência de 45 e 6%, intensidade média de 3,17 e 2,83, variando de 1 a 20 e 1 a 5, e abundância média de 1,43 e 0,06, respectivamente. Larvas de Anisakis sp. e essas duas espécies de Trypanorhyncha foram registradas pela primeira vez parasitando A. monoceros.

Oral inoculation with Gymnorhynchus gigas induces anti-parasite anapyhylactic antibody production in both mice and rats and adverse reactions in challenge mice

This study was performed to mimic human consumption of fish flesh infected with larvae of the fish cestode Gymnorhynchis gigas and examine possible side effects thereof. Both a rat and a mouse G. gigas oral inoculation model were used. The rat model was evaluated according to propensity to induce stress responses in three tissues and anaphylactic antibody production. The mouse model measured anti-G. gigas IgG, M and A (H + L) levels in intestinal fluids, fecal suspensions and serum and specific serum IgE levels by enzyme-linked immunosorbent assay. Additionally, biological activity of anaphylactic antibodies in test mice and rats were evaluated utilizing challenge reinoculation(s) and intradermal skin testing, respectively. With the rat inoculation model, we noted both occurrence of a shock response, viz. increased expression of heat shock proteins in intestine and spleen, and of immediate-type skin reactions. No positive wheals were seen on skin sites treated with PBS or soluble Trichinella spiralis extract. With the mouse model, our results showed that all body fluids tested had significantly more anti-G. gigas IgG, M and A (H + L) than their counterparts from either PBS-treated or T. spiralis-infected controls. In addition, the mouse G. gigas model had significantly higher specific serum IgE. When challenged by oral route all test mice (n = 5) manifested immediate-type signs of distress. Repeated exposure to the "allergen", produced clinical signs appearing more rapidly and persisting longer. These findings suggest that feeding on fish infected with G. gigas plerocercoids triggers the production of anaphylactic-type antibodies in both rats and mice and, by implication, possibly also in humans.