Morphological and molecular diagnosis of anisakid nematode larvae from cutlassfish (Trichiurus lepturus) off the coast of Rio de Janeiro, Brazil.
Anisakid nematode larvae from Trichiurus lepturus off coast of Rio de Janeiro were studied using light, laser confocal and scanning electron microscopy, in addition to a molecular approach. Mitochondrial cytochrome c-oxidase subunit 2 (mtDNA cox-2), partial 28S (LSU) and internal transcribed spacers (ITS-1, 5.8S, ITS-2) of ribosomal DNA were amplified using the polymerase chain reaction and sequenced to evaluate the phylogenetic relationships between the nematode taxa. The morphological and genetic profiles confirmed that, of the 1,030 larvae collected from the 64 fish examined, 398 were analysed, of which 361 were Hysterothylacium sp. and 37 were Anisakis typica. Larvae of Hysterothylacium sp. were not identified to the species level due to the absence of similar sequences for adult parasites; however, the ITS sequence clustered in the phylogenetic tree with sequences of H. deardorffoverstreetorum, whereas an mtDNA cox-2 and LSU concatenated phylogenetic analysis demonstrated the presence of two clades, both of them under the same name as the larval H. deardorffoverstreetorum. Data on the occurrence of parasites during the winter and summer months were compared using the t-test. The greatest prevalence and intensity of infection were recorded for larval Hysterothylacium, with a prevalence of 51.56% and an intensity of up to 55 parasites per fish. The larval Anisakis exhibit a higher abundance and intensity of infection in the winter months, and those of Hysterothylacium during the summer. However, the t-test indicated no significant differences between the abundance and intensity of infection recorded during the months of collection for either of these larval nematodes. All sequences generated in this study were deposited in GenBank.
Laboratório de Avaliação e Promoção e Saúde Ambiental, Instituto Oswaldo Cruz, Rio de Janeiro, Brasil.
Juliana Novo
JN
Borges
Luiz Felipe Gullo
LF
Cunha
Helena Lúcia Carneiro
HL
Santos
Cassiano
C
Monteiro-Neto
Cláudia
C
Portes Santos
D000818:Animals; D017129:Anisakiasis / Q000175:diagnosis / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D017163:Anisakis / Q000033:anatomy & histology* / Q000235:genetics; D001483:Base Sequence; D001938:Brazil / Q000453:epidemiology; D051546:Cyclooxygenase 2 / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D005393:Fish Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000469:parasitology*; D017238:Genes, Helminth; D015801:Helminth Proteins / Q000235:genetics; D007814:Larva / Q000033:anatomy & histology / Q000235:genetics; D016013:Likelihood Functions; D025202:Molecular Diagnostic Techniques; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D010473:Perciformes / Q000469:parasitology*; D010802:Phylogeny; D015995:Prevalence; D012689:Sequence Homology, Nucleic Acid
D004272:DNA, Mitochondrial; D021903:DNA, Ribosomal Spacer; D015801:Helminth Proteins; D051546:Cyclooxygenase 2