Efferent intestinal lymph protein responses in nematode-resistant, -resilient and -susceptible lambs under challenge with Trichostrongylus colubriformis.

The mechanisms underlying resistance to challenge by gastrointestinal nematode parasites in sheep are complex. Using DIGE, we profiled ovine lymph proteins in lambs with host resistance (R), resilience (Ri) or susceptibility (S) to a daily trickle challenge with the nematode Trichostrongylus colubriformis. Efferent intestinal lymph was collected prior to infection (day 1) and on days 5 and 10 post-infection. Eight proteins identified by LC-MS/MS, showed differences relating to host genotype. Of these, Serpin A3-3 and Serpin A3-7 have not been reported previously in the lymph proteome. Three acute phase proteins showed significant differences relating to interactions between breeding line and parasite challenge, including complement C3ß, C3α and haptoglobin (Hp) ß. In the R lambs C3α was significantly up regulated (P<0.05) on day 10, while in the Ri lambs Hp ß was significantly down regulated (P<0.05). In the S lambs, levels of C3ß were up regulated and levels of Hp ß down regulated (both P<0.05) on day 10. Hence we demonstrate that acute phase inflammation proteins contribute to differences in the innate immune response of sheep to challenge by T. colubriformis. The findings may lead to the development of new approaches to combat nematode infestations in sheep production systems. BIOLOGICAL SIGNIFICANCE: Breeding lines of sheep with resistance (R), resilience (Ri) or susceptibility (S) to nematode infections provide an experimental model to examine the biological mechanisms underlying the ability of some sheep to expel worms and remain healthy without the use of an anthelmintic. Using proteomics we identified differences in the expression of acute phase lymph proteins in the R, Ri and S lambs. The results will assist the development of alternative control strategies to manage nematode infections in livestock.

Dynamics of the free-living stages of sheep intestinal parasites on pasture in the North Island of New Zealand. 1. Patterns of seasonal development.

AIM: To describe the seasonal pattern of development of third-stage infective larvae (L3) from eggs of Teladorsagia (=Ostertagia) circumcincta, Trichostrongylus colubriformis and Haemonchus contortus on pasture in the North Island of New Zealand. METHODS: Sheep faeces containing known numbers of eggs of all three nematode species were deposited on, or buried in, pasture plots at three sites, viz coastal Manawatu, Upper Hutt Valley, and East Cape hill country. Development was measured by recovering L3 from faeces, herbage and soil 28-31 days after deposition on 13-18 occasions, between January 2005 and July 2006. Analysis of the number of larvae recovered used a mixed model including number of eggs deposited, weight of faeces recovered (an assumed indicator of earthworm activity), site, contamination date, and position of deposited faeces, i.e. on the surface or buried. RESULTS: There was a significant effect of contamination date on development of all three species, with maximum numbers of L3 developing between late spring (November) and early autumn (March), and minimum numbers in June and July. There were large differences between species, with H. contortus exhibiting a long period (April to October) where development was close to zero, whereas T. circumcincta developed to some extent all year round. Development of T. colubriformis was intermediate between the other two species. Burying faeces containing nematode eggs increased the number of L3 recovered compared with surface deposition (p ≤ 0.001), although there were a small number of exceptions involving only T. colubriformis. The weight of faeces recovered at harvest, which was assumed to be an indication of earthworm activity, was correlated with the number of L3 recovered for all species (p<0.001). In a separate analysis, earthworms were assumed to have been active if <5 g faeces remained at harvest. Where this occurred, the number of L3 of T. colubriformis and T.circumcincta recovered was reduced by 56% and 58%, respectively (p<0.001). CONCLUSIONS: A marked seasonal pattern of development was observed for all three species, with the most larvae developing in spring-early autumn and the least in winter. This seasonal pattern was most pronounced in H. contortus and least obvious in T. circumcincta. Burying faeces containing eggs generally resulted in more L3 being recovered, whilst the apparent activity of earthworms resulted in fewer larvae being recovered.

Electromagnetic treatment of New Zealand flower thrips (Thrips obscuratus, Thysanoptera:Thripidae) in deionized water.

To evaluate the impact of an electromagnetic field on thrips, New Zealand flower thrips, Thrips obscuratus (Crawford), were contained in a pipette that was suspended in an acrylic cylinder containing deionized water. Electrodes, set 85 mm apart at each end of the cylinder, were in contact with the water. Voltages of between 10 and 100 kV d.c., as impulses or in steady state, were applied to the electrodes. Voltages of 10 and 15 kV applied in steady state did not kill all of the thrips. Only 2% of thrips remained alive when a voltage of 20 kV was applied for 10 sec. Complete mortality was achieved with 25 or 30 kV for 5 and 10 sec. None of the impulse trains, varying from 50 to 100 kV and 20 to 60 impulses, killed thrips or caused thrips to become moribund. Thrips were killed when exposed to 20 kV and 10 pulses when electrodes were modified and placed very close together.