Identification and Characteristics of Haemozoin of a Hematophagous Haemonchus Contortus

Abstract

Abstract Background The majority of hematophagous organisms constantly suck the host’s hemoglobin that produces the toxic free haem. This toxic haem aggregation into the nontoxic crystallization complex known as hemozoin, which represents one of the most important detoxification pathways in living organisms, but very little is known about the features of haemozoin in parasitic nematodes. Here, we identified and characterized the haemozoin of an economically significant blood-sucking nematode, Haemonchus contortus. Methods Using electron microscopy, spectrophotometry analyses and biochemical approaches, haemozoin crystallization was identified and characterized in parasitic fourth-stage larvae (L4) and/or adult worms as well as L4 of in vitro culture. Results The haemozoin was formed in intestinal lipid droplets of the parasitic L4 and adult worms, and its appearance was regularly spherical shapes with a 400 nm absorption peak. Furthermore, the haemozoin of L4 of in vitro culture was associated with the time and concentration of the blood medium, and its formation could be inhibited by chloroquine-derived drugs. Conclusions This work provides the first detailed insight into the haemozoin formation of H. contortus and should have important implications for developing novel therapeutic targets against this parasite or related hematophagous organisms.