Iron supplementation for lambs experimentally infected by Haemonchus contortus: response to anemia and iron store in the bone marrow / Suplementação com ferro em cordeiros infectados experimentalmente por Haemonchus contortus: resposta a anemia e as reservas de ferro na medula óssea

To evaluate the effect of supplementation of iron dextran on blood variables and iron metabolism in lambs experimentally infected by Haemonchus contortus, four experimental groups were used: uninfected and non-supplemented animals (GI); infected animals supplemented with iron (GII); uninfected animals supplemented with iron (GIII); and infected non-supplemented animals (GIV). Groups II and IV received 10,000 larvae (L3) of Haemonchus contortus, and groups II and III received three doses of iron dextran (20mg/kg) intramuscularly with seven days of interval. Blood and faeces samples were collected on days 10 (D10), 17 (D17), 24 (D24), and 31 (D31), in order to determine red blood cell counts, iron metabolism, and EPG. Infected animals developed anemia from D24 and anemia was more severe on D31. Animals from GII had higher hematocrit and hemoglobin concentration compared to animals of GIV on D31. Iron stores in the bone marrow were higher in GII and GIII compared to GI and GIV. The GIV showed lower seric levels of iron on D24 compared to the other groups. The iron supplementation reduces the severity of the anemia caused by infection with Haemonchus contortus in lambs, improving erythropoietic response after blood loss.(AU)

Para avaliar o efeito da suplementação de ferro dextrano sobre variáveis sanguíneas e metabolismo do ferro em cordeiros experimentalmente infectados por Haemonchus contortus, foram utilizados quatro grupos experimentais: animais não infectados e não suplementados (GI); animais infectados e suplementados com ferro (GII); animais não infectados e suplementados com ferro (GIII); e animais não suplementados infectados (GIV). Os grupos II e IV receberam 10.000 larvas (L3) de Haemonchus contortus, e os grupos II e III receberam três doses de ferro dextrano (20mg/kg) por via intramuscular com sete dias de intervalo. As amostras de sangue e fezes foram coletadas nos dias 10 (D10), 17 (D17), 24 (D24) e 31 (D31), para determinar o eritrograma, o metabolismo do ferro e a quantidade de ovos por gramas de fezes (OPG). Os cordeiros infectados desenvolveram anemia no D24, sendo esta mais severa no dia 31. Os cordeiros do GII apresentaram maior hematócrito e concentração de hemoglobina em comparação com animais dd GIV no D31. Os estoques de ferro na medula óssea foram maiores no GII e GIII em comparação com o GI e GIV. O GIV mostrou menores níveis séricos de ferro no D24 em comparação com os outros grupos. A suplementação de ferro reduz a gravidade da anemia causada por infecção por Haemonchus contortus em cordeiros, melhorando a resposta eritropoietica após a perda de sangue.(AU)

Cloning and characterization of a selenium-independent glutathione peroxidase (HC29) from adult Haemonchus contortus

The complete coding sequence of Haemonchus (H.) contortus HC29 cDNA was generated by rapid amplification of cDNA ends in combination with PCR using primers targeting the 5'- and 3'-ends of the partial mRNA sequence. The cloned HC29 cDNA was shown to be 1,113 bp in size with an open reading frame of 507 bp, encoding a protein of 168 amino acid with a calculated molecular mass of 18.9 kDa. Amino acid sequence analysis revealed that the cloned HC29 cDNA contained the conserved catalytic triad and dimer interface of selenium-independent glutathione peroxidase (GPX). Alignment of the predicted amino acid sequences demonstrated that the protein shared 44.7~80.4% similarity with GPX homologues in the thioredoxin-like family. Phylogenetic analysis revealed close evolutionary proximity of the GPX sequence to the counterpart sequences. These results suggest that HC29 cDNA is a GPX, a member of the thioredoxin-like family. Alignment of the nucleic acid and amino acid sequences of HC29 with those of the reported selenium-independent GPX of H. contortus showed that HC29 contained different types of spliced leader sequences as well as dimer interface sites, although the active sites of both were identical. Enzymatic analysis of recombinant prokaryotic HC29 protein showed activity for the hydrolysis of H2O2. These findings indicate that HC29 is a selenium-independent GPX of H. contortus.

Characterization of HC58cDNA, a putative cysteine protease from the parasite Haemonchus contortus

Because of the complexity of the cathepsin B-like (CBL) family, an information on the biological and biochemical characteristics of individual CBL genes is lacking. In this study, we investigated the degradative effects of the recombinant HC58 protein isolated from Haemonchus contortus parasites on protein substrates over a broad pH range in vitro. This protein, which hydrolyzed the synthetic peptide substrates Z-FR-AMC and Z-RR-AMC, had characteristics of the cysteine protease class of proteins. In the acidic pH range, the isolated protein actively degraded hemoglobin (Hb), the heavy chain of goat immunoglobulin G, and azocasein. By contrast, it degraded fibrinogen in the alkaline pH range. These activities were strongly inhibited in the presence of the cysteine protease inhibitor E-64. While the protein digested Hb, it did not induce the agglutination of erythrocytes from its natural host. These results suggest that the HC58 protein may play a role in the nutrition of this parasite.