Proteomic Analysis of Mecistocirrus digitatus and Haemonchus contortus Intestinal Protein Extracts and Subsequent Efficacy Testing in a Vaccine Trial

Abstract

BackgroundGastrointestinal nematode infections, such as Haemonchus contortus and Mecistocirrus digitatus, are ranked in the top twenty diseases affecting small-holder farmers' livestock, yet research into M. digitatus, which infects cattle and buffalo in Asia is limited. Intestine-derived native protein vaccines are effective against Haemonchus, yet the protective efficacy of intestine-derived M. digitatus proteins has yet to be determined.Methodology/Principal FindingsA simplified protein extraction protocol (A) is described and compared to an established method (B) for protein extraction from H. contortus. Proteomic analysis of the H. contortus and M. digitatus protein extracts identified putative vaccine antigens including aminopeptidases (H11), zinc metallopeptidases, glutamate dehydrogenase, and apical gut membrane polyproteins. A vaccine trial compared the ability of the M. digitatus extract and two different H. contortus extracts to protect sheep against H. contortus challenge. Both Haemonchus fractions (A and B) were highly effective, reducing cumulative Faecal Egg Counts (FEC) by 99.19% and 99.89% and total worm burdens by 87.28% and 93.64% respectively, compared to the unvaccinated controls. There was no effect on H. contortus worm burdens following vaccination with the M. digitatus extract and the 28.2% reduction in cumulative FEC was not statistically significant. However, FEC were consistently lower in the M. digitatus extract vaccinates compared to the un-vaccinated controls from 25 days post-infection.Conclusions/SignificanceSimilar, antigenically cross-reactive proteins are found in H. contortus and M. digitatus; this is the first step towards developing a multivalent native vaccine against Haemonchus species and M. digitatus. The simplified protein extraction method could form the basis for a locally produced vaccine against H. contortus and, possibly M. digitatus, in regions where effective cold chains for vaccine distribution are limited. The application of such a vaccine in these regions would reduce the need for anthelmintic treatment and the resultant selection for anthelmintic resistant parasites.

Proteomic identification of galectin-11 and 14 ligands fromHaemonchus contortus

“…Another important metalloprotease is H11 family which has been shown to provide protection when used as vaccine antigen ( Newton & Munn, 1999 ). Several studies isolated zinc metallopeptidases from crude extracts of H. contortus using lectins that have a binding preference to β-D-galactose and, following vaccination of sheep, led to reduced worm burdens following challenge infection ( Dicker et al, 2014 ; Newlands et al, 2006 ; Smith et al, 1999 ; Smith et al, 2000 ). It appears inhibition of metalloproteases interferes with ability of H. contortus to digest its blood meal.…”

Advances in the Development of Anti-Haemonchus contortus Vaccines: Challenges, Opportunities, and Perspectives

“…Genome-wide transcriptomic data from all the key developmental stages of H. contortus revealed 23,610 protein-coding genes involved in host–parasite interactions, development, reproduction, immunity, and disease [ 44 ]. A comprehensive proteomic analysis using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS or MALDI-TOF-MS/MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS) pointed out 107 identities from 102 spots [ 45 ], including novel groups of proteins, such as aminopeptidases (H11), zinc metalloproteases, serine and aspartic proteases [ 46 , 47 , 48 ], and the most important immunogenic vaccines components of H. contortus ESPs (HcESPs) such as Hc-15, Hc-24, Hc-40, and apical gut proteins (GA1) [ 45 , 49 , 50 ]. Furthermore, in LC-MS/MS analysis, ≈4400 unique proteins were identified at initial host and parasite interaction (3 days post infection) [ 51 ].…”

Perusal of parasitic nematode ‘omics in the post-genomic era

“…Congruent with the emergence of drug resistance in H. contortus , a comparative analysis of the proteome from ivermectin-resistant and -susceptible worms showed an increased proportion of proteins involved in metabolic detoxification in the resistant isolate [88]. Additional proteomics work has identified potential vaccine candidates [89, 90]. …”