Immunization Trials with Recombinant Major Sperm Protein of the Bovine Lungworm Dictyocaulus viviparus

The lungworm Dictyocaulus viviparus is one of the most economically important bovine parasites in temperate climate regions. Following infection, D. viviparus induces a temporary protective immunity, and a vaccine based on attenuated, infective larvae is commercially available. However, due to several disadvantages of the live vaccine, the development of a recombinant subunit vaccine is highly desirable. Therefore, the major sperm protein (MSP), which is essential for the parasite’s reproduction, was tested as a recombinantly Escherichia coli-expressed glutathione-S-transferase (GST)-fused vaccine antigen in immunization trials with two different adjuvants, Quil A and Al(OH)3. Calves (N = 4 per group) were immunized on study day (SD) 0, 21 and 42 and given a challenge infection on SD 63–65. The two control groups received only the respective adjuvant. Based on geometric means (GM), a 53.64% reduction in larvae per female worm was observed in the rMSP Quil A group vs. its control group (arithmetic means (AM): 54.43%), but this difference was not statistically significant. In the rMSP Al(OH)3 group, the mean number of larvae per female worm was even higher than in the respective control group (GM: 9.24%, AM: 14.14%). Furthermore, male and female worm burdens and the absolute number of larvae did not differ significantly, while the Al(OH)3 control group harbored significantly longer worms than the vaccinated group. Vaccinated animals showed a rise in rMSP-specific antibodies, particularly IgG and its subclass IgG1, and the native protein was detected by immunoblots. Although rMSP alone did not lead to significantly reduced worm fecundity, it might still prove useful as part of a multi-component vaccine.

Genus-level evolutionary relationships of FAR proteins reflect the diversity of lifestyles of free-living and parasitic nematodes

Background Nematodes are a widespread and diverse group comprising free-living and parasitic species, some of which have major detrimental effects on crops, animals, and human health. Genomic comparisons of nematodes may help reveal the genetic bases for the evolution of parasitic lifestyles. Fatty acid and retinol-binding proteins (FARs) are thought to be unique to nematodes and play essential roles in their development, reproduction, infection, and possibly parasitism through promoting the uptake, transport, and distribution of lipid and retinol. However, the evolution of FAR family proteins across the phylum Nematoda remains elusive. Results We report here the evolutionary relationship of the FAR gene family across nematodes. No FAR was found in Trichocephalida species and Romanomermis culicivorax from Clade I, and FAR could be found in species from Clades III, IV, and V. FAR proteins are conserved in Clade III species and separated into three clusters. Tandem duplications and high divergence events lead to variable richness and low homology of FARs in Steinernema of Clade IVa, Strongyloides of Clade IVb, and intestinal parasitic nematodes from Clades Vc and Ve. Moreover, different richness and sequence variations of FARs in pine wood, root-knot, stem, and cyst nematodes might be determined by reproduction mode or parasitism. However, murine lungworm Angiostrongylus and bovine lungworm Dictyocaulus viviparus from Clade Vd have only 3–4 orthologs of FAR. RNA-seq data showed that far genes, especially far-1 and far-2, were highly expressed in most nematodes. Angiostrongylus cantonensis FAR-1 and FAR-3 have low sequence homology and distinct ligand-binding properties, leading to differences in the cavity volume of proteins. These data indicate that FAR proteins diverged early and experienced low selective pressure to form genus-level diversity. The far genes are present in endophyte or root-colonized bacteria of Streptomyces, Kitasatospora sp., Bacillus subtilis, and Lysobacter, suggesting that bacterial far genes might be derived from plant-parasitic nematodes by horizontal gene transfer. Conclusions Data from these comparative analyses have provided insights into genus-level diversity of FAR proteins in the phylum Nematoda. FAR diversification provides a glimpse into the complicated evolution history across free-living and parasitic nematodes.

Teladorsagia circumcincta 1,6-Bisphosphate Aldolase: Molecular and Biochemical Characterisation, Structure Analysis and Recognition by Immune Hosts

A 1095 bp full length cDNA encoding Teladorsagia circumcincta aldolase (TciALDO-1) was cloned and expressed in Escherichia coli. Recombinant TciALDO-1 was purified, and its kinetic properties determined. The predicted protein consisted of 365 amino acids, and was present as a single band of about 44 kDa on SDS-PAGE. Multiple alignments of the protein sequence of TciALDO-1 with homologues from other helminths showed the greatest similarity (93%) to the aldolases of Haemonchus contortus and Dictyocaulus viviparus, 82–86% similarity to the other nematode sequences, and 68–71% similarity to cestode and trematode enzymes. Substrate binding sites and conserved regions were identified, and were completely conserved in other homologues. At 30 °C, the optimum pH for TciALDO-1 activity was pH 7.5, the Vmax was 432 ± 23 nmol × min−1 × mg−1 protein, and the apparent Km for the substrate fructose 1,6-bisphosphate was 0.24 ± 0.01 µM (mean ± SEM, n = 3). Recombinant TciALDO-1 was recognized by antibodies in both serum and saliva from field-immune sheep in ELISA, however, that was not the case with nematode-naïve sheep. Teladorsagia circumcincta fructose 1,6-bisphosphate aldolase appears to have potential as a vaccine candidate to control this common sheep parasite.

On the epidemiology of helminth parasites in Hangul Deer Cervus hanglu hanglu (Mammalia: Artiodactyla: Cervidae) of Dachigam National Park, India

A one-year study conducted to ascertain the prevalence and risk factors associated with helminth infection in Hangul Deer Cervus hanglu hanglu at Dachigam National Park revealed that 40.45% (89 of 220 samples) were infected with four helminth species including Heamonchus contortus, Trichuris ovis, Dictyocaulus viviparus, and Moneizia expansa. The study signified that the infection was more prevalent during the dry season (summer and autumn) as compared to the wet season (winter and spring). The overall prevalence of Heamonchus contortus was the highest (23.18%) followed by Trichuris ovis (8.18%), followed by Dictyocaulus viviparus (5.45%), and Moneizia expansa (3.63%). The present study should be of importance in conserving the erstwhile state animal, listed as Critically Engendered in 2017 by IUCN.

Prevalence of strongylids of pigs in Ogun State, southwest Nigeria

This study was carried out to determine the prevalence of strongyles infecting pigs in Ogun State , Southwestern Nigeria. Faecal samples were collected from 209 pigs which were initially screened by centrifugal sedimentation technique. Faeces positive nematode eggs were then cultured using a modified Baermann's technique. Out of the 36.8% (77/209) infected pigs, 84.4%, 58.4%, 57.1%, 19.5% and 6.5% were for Hyostrongylus rubidus, Trichostrongylus colubriformis, Oesophagostomum spp., Strongyloides ransomi and Dictyocaulus viviparus respectively. Mixed infection with various nematode species accounted for 94.8% of the prevalence. The infection rate in piglets (43.7%) was higher than in weaners and adults without any significant differences. Similarly no significant differences were observed between diarrhoeic and non-diarrhoeic pigs. The results of this study thus showed the economic importance of strongylid nematode infections in intensively reared pigs in Ogun state. Regular screening to ascertain worm load and species involved will facilitate appropriate control and prevention strategies.

DICTIOCAULOSE EM BOVINOS NO MUNICÍPIO DE LONDRINA, PR, BRASIL

A dictiocaulose é uma afecção respiratória causada por helmintos do gênero Dictyocaulus spp., considerada potencial causa de queda na produtividade e morte de bovinos no Brasil e em outros países do mundo. Este trabalho descreve o relato de infecção por Dictyocaulus viviparus e dictiocaulose em bovinos no município de Londrina, PR. A associação das condições ambientais, nutricionais e imunológicas, juntamente com controle parasitário inadequado favoreceu o desenvolvimento da doença, ressaltando a importância da afecção como diagnóstico diferencial de doenças respiratórias dos bovinos na Região Sul do Brasil.

Teladorsagia circumcincta 1,6 bisphosphate aldolase: molecular and biochemical characterisation, structure analysis and recognition by immune hosts

ABSTRACTA 1095 bp full length cDNA encoding Teladorsagia circumcincta aldolase (TciALDO) was cloned, expressed in Escherichia coli, the recombinant protein purified and its kinetic properties determined. A phylogenetic tree was constructed using helminth aldolase sequences. The predicted protein consisted of 365 amino acids and was present as a single band of about 44 kDa on SDS-PAGE. Multiple alignments of the protein sequence of TciALDO with homologues from other helminths showed that the greatest similarity (93%) to the aldolases of Haemonchus contortus and Dictyocaulus viviparus, 82-86% similarity to the other nematode sequences and 68-71% similarity to cestode and trematode enzymes. Substrate binding sites and conserved regions were identified and were completely conserved in other homologues. At 25 °C, the optimum pH for TciALDO activity was pH 7.5, the Vmax was 432 ± 23 nmoles.min−1.mg−1 protein and the apparent Km for the substrate fructose 1,6-bisphosphate was 0.24 ± 0.01 μM (mean ± SEM, n = 3). Antibodies in both serum and saliva from field-immune, but not nematode-naïve, sheep recognised recombinant TciALDO in enzyme-linked immunosorbent assays. The recognition of the recombinant protein by antibodies generated by exposure of sheep to native aldolase indicates similar antigenicity of the two proteins.

Dictiocaulosis en vacas de cría en la provincia de Buenos Aires, Argentina: descripción de dos brotes

La dictiocaulosis o bronquitis verminosa es ocasionada por Dictyocaulus viviparus, un nematode de ciclo de vida directo, y está asociada mayormente a brotes de enfermedad clínica en bovinos jóvenes en su primera temporada de pastoreo. El presente trabajo describe dos brotes de bronquitis verminosa que provocó la mortandad de entre el 13,6 y el 15,7% de dos rodeos de vacas de cría de establecimientos de la provincia de Buenos Aires, Argentina. En ambos brotes, los hallazgos clínico-patológicos en los animales afectados y la presencia de nematodes pulmonares, en algunos casos solo observados en el estudio histopatológico, permitieron confirmar este diagnóstico.