Characterization of Ostertagia ostertagi annexin-like proteins at different developmental stages.

Ostertagiosis remains an economically important parasitic disease in cattle in the temperate regions of the world. Repeated exposures to Ostertagia ostertagi in calves cause significant pathology in the abomasum but elicit little protective immunity. The larvae use the host's gastric glands as a niche for development, where the parasite completes its parasitic stages, while in the gastric glands, the larvae must down-regulate the host inflammatory immune responses. Annexin (ANX) A1, commonly found in most eukaryotes, is heavily involved in controlling anti-inflammatory responses by binding receptors on leukocytes. We hypothesized, therefore, that parasite proteins of the ANX family may be involved in host-parasite interactions during ostertagiosis. BLASTN search with the bovine ANXA1 identified two families of Oos-ANX like proteins (Oos-ANXL), each of which was highly conserved at the genetic level and identical at the amino acid sequence level. Oos-ANXL-1 is encoded by two transcripts and Oos-ANXL-2 by 20 transcripts. The present study characterized one Oos-ANXL, representing the most abundant Oos-ANXL, which was further defined as Oost-ANXL-2.1. Oos-ANXL-2.1 with a coding sequence of 519 bp was PCR-amplified, cloned, and expressed. Oos-ANXL-2.1 was immunolocalized to both L3 and adult, but not L4. The staining appeared to be associated with the gut and hypodermis in L3, but it was specifically localized to the hypodermis in adult worms. Western blots detected three protein bands in parasite lysates using anti-recombinant Oos-ANXL-2.1 antibody. Integrated optical density for each of the 3 Oos-ANXL-2s or the total Oos-ANXL-2s detected by Western blots (P < 0.05) was higher in adult worms than in L3 or L4. The results indicate that the production of Oos-ANXL-2s is developmentally regulated and most abundant in the adult worm. This rather large family of proteins could be a potential vaccine target against O. ostertagi infection and warrants further investigation.

Prevalence of Ostertagia ostertagi lesions in slaughtered dairy cattle from São Miguel Island, Azores, Portugal.

Ostertagiosis caused by Ostertagia ostertagi is considered the most important parasitosis in dairy cattle raised in temperate areas. The aim of this investigation was to determinate the prevalence of ostertagiosis in cattle slaughtered in São Miguel Island (SMI), Azores, the geographical distribution of positive cases, its economic impact and farmers awareness regarding preventive and control measurements against this parasitosis. From the 2000 animals sampled, 1282 presented lesions compatible with ostertagiosis representing a prevalence of 49.0% in young animals and 75.7% in adults. Positive animals had significantly worse carcass rating when slaughtered and the fat rating of positive uncastrated males older than 24months was also significantly lower. The presence of lesions compatible with ostertagiosis resulted in a total weight loss of 2.810.89kg (2.19kg mean weight loss per animal - 1.07% carcass weight drop), which extrapolating to the total of animals slaughtered in SMI in 2014 corresponds to a value of losses of roughly about 91.000.00€. Our data also indicate that ostertagiosis has a widespread distribution throughout the Island and that 85.7% of the farmers dewormed calves and 42.9% dewormed cows (only one administration was provided for each deworming). Data shows that ostertagiosis represents an important economical lost in dairy cattle from SMI and a significant lack of knowledge by farmers about the benefits of deworming and preventive management practices.