NK cell receptors in rodents and cattle

Natural killer (NK) cells discriminate between normal syngeneic cells and infected, neoplastic or MHC-disparate allogeneic cells. The reactivity of NK cells appears to be regulated by a balance between activating receptors that recognize non-self or altered self, and inhibitory receptors recognizing normal, self-encoded MHC class I molecules. Subfamilies of NK receptors undergo rapid evolution, and appear to co-evolve with the MHC. We here review present views on the evolution and function of NK cell receptors, with an emphasis on knowledge gained in cattle and rodents.     

Targeting the tick protective antigen subolesin reduces vector infestations and pathogen infection by Anaplasma marginale and Babesia bigemina

The ultimate goal of vector vaccines is the control of vector infestations while reducing pathogen infection and transmission to protect against the many diseases caused by vector-borne pathogens. Previously (Vaccine 2011;29:2248-2254), we demonstrated that subolesin vaccination and release of tick larvae after subolesin knockdown by RNA interference (RNAi) were effective for the control of cattle tick, Rhipicephalus (Boophilus) microplus infestations in cattle. In this study, we used the fact that these animals were naturally infected with Anaplasma marginale and Babesia bigemina to evaluate the effect of subolesin vaccination and gene knockdown on tick infection by these cattle tick-transmitted pathogens. Ticks fed on vaccinated cattle had lower subolesin mRNA levels when compared to controls, resembling RNAi results. A. marginale and B. bigemina infection was determined by PCR and decreased by 98% and 99%, respectively in ticks fed on vaccinated cattle and by 97% and 99%, respectively after subolesin knockdown. These results demonstrated that targeting subolesin expression by vaccination or RNAi results in lower subolesin mRNA and pathogen infection levels, probably due to the effect of subolesin downregulation on tick feeding, gene expression and gut and salivary glands tissue development and function. These results suggested that subolesin vaccines could be used for the dual control of tick infestations and pathogen infection, a result that could be relevant for other vectors and vector-borne pathogens.     

宋代牛疫的流行与防治

宋代由于国营牧监南移、气候反常变化、畜舍环境卫生不良和长途迁徙不服水土等多方面的原因,导致牛疫多次流行,不仅造成牛群的大批死亡,而且也造成农业畜力的锐减,威胁到粮食生产的稳定,对宋代社会产生了重要影响,引起不同社会阶层的关注。宋代对牛疫的认识主要集中在“未病先防”和“既病防染”两方面,宋政府采取医学措施和经济措施进行了积极的防治,如：派遣兽医、赐药和颁方,规范养牧法;修改法律,允许耕牛买卖;推广新式农具,防止“耕稼失时”等,对牛疫的防治取得了一定成效。     

Simultaneous detection of Aspergillus nidulans,Aspergillus luchuensis and Lichtheimia sp. in a bovine abortion

Abortion in dairy cattle may be caused by infectious (viruses, fungi and protozoa) and non-infectious causes mostly related to bad management practices and genetic factors. Recently, the significant contribution of mycotic infection to bovine abortion has been recognized. This report describes an abortion case in a Chianina cow due to Aspergillus nidulans, Aspergillus luchuensis and Lichtheimia sp. diagnosed by histology, cytology, culture and molecular assays. A mixed infection due to more than one fungus in abortion is rarely demonstrated. To our knowledge, this is the first case of bovine abortion caused by co-infection with three different moulds.     

Bovine abortion,stillbirth and neonatal death associated with Babesia bovis and Anaplasma sp. infections in southern Brazil

Anaplasmosis and babesiosis are tick-borne diseases widely disseminated in cattle herds in many parts of the world. These diseases represent important causes of death and economic losses in several countries, including Brazil, and are characterized by hemolytic disease and anemia. Animals of all ages may be affected. Although transplacental infections are known to occur, abortion, stillbirth and neonatal death directly associated with Anaplasma marginale and especially Babesia spp. infections have rarely been documented in cattle. The objective of the present study is to describe the pathological and molecular findings of two cases of bovine abortion, two cases of stillbirth and two cases of neonatal death associated with intrauterine anaplasmosis and/or babesiosis in southern Brazil. All cases occurred in beef farms in the state of Rio Grande do Sul, between 2017 and 2019. Angus and crossbred calves were affected. At the necropsy, the main gross lesions observed included different degrees of splenomegaly, enlarged and yellow liver, thick and grumous bile, pallor or jaundice of mucous membranes and carcass, and dark kidneys. Four calves also presented cherry-pink discoloration of the central nervous system. Cytological slides enabled the observation of intraerythrocytic organisms consistent with Babesia bovis (3/6) and A. marginale (2/6). Through PCR assays, it was possible to detect three cases of Babesia sp. infection alone, and one case of Anaplasma sp. infection alone. Co-infections with Anaplasma sp. and Babesia sp. were detected in two cases. These findings reaffirm that anaplasmosis and babesiosis should be considered as an important differential diagnosis of fetal loss, stillbirth and neonatal death in cattle in areas where these diseases occur.     

Paratuberculosis vaccination specific and non-specific effects on cattle lifespan

Records of cattle vaccination against paratuberculosis (PTB) have been analyzed to determine whether or not non-specific effect (NSE) on overall mortality similar to that observed in BCG vaccinated humans occurs in animals. The results of a previously reported slaughterhouse study on PTB prevalence were used as a reference on the age incidence of advanced patent (clinical) epidemio-pathogenic forms. In the proper vaccine study, cows in 30 cattle farms in the Basque Country, Spain were followed-up for between 1 and 13 years. Vaccinated groups were composed by 1008 (592 right-censored) animals younger than 3 months treated as calves and by 3761 (3160 right-censored) vaccinated at any older age. Controls were 339 (157 right-censored) and 4592 (2213 right-censored) age matched animals, respectively. Individual last year presence in the annual testing was considered age at culling or death. A survival analysis was carried out according age at vaccination of vaccinated versus non-vaccinated animals. PTB age incidence in the slaughterhouse study was subtracted from the difference between vaccinated and non-vaccinated animals at the same age in order to estimate PTB-specific and non-specific effects. The maximum difference was observed at the 2–3 years interval with a 33.9% mortality reduction in the calf vaccinated group. This corresponded also with the maximum NSE that was 24.5% for a PTB incidence of 9.5%. Overall, vaccination afforded to calves a 26.5% yearly mortality protection, split between 11.1% PTB-specific and 15.4% NSE. These results support a NSE on total mortality associated with PTB vaccination that appeared to persist for up to 6–7 years. This confirms for the first time in an animal field study the innate immune system memory predicted by the recently proposed trained immunity theory. Contrasting the literature, no deleterious effects of killed vaccines on females were observed. Mortality reduction would offset vaccination costs and could improve livestock systems efficiency and potentially reduce antibiotic use.Clinical trial registered with Spanish Agency for Drugs and Sanitary products (AEMPS) as 11/012/ECV.     

PCR and microsatellite analysis of diminazene aceturate resistance of bovine trypanosomes correlated to knowledge,attitude and practice of livestock keepers in South-Western Ethiopia

African Animal Trypanosomosis is threatening the agricultural production and cattle breeding more severely than any other livestock disease in the continent, even more since the advent of drug resistance. A longitudinal study was conducted from November 2012 to May 2013 in the Ghibe valley to evaluate diminazene aceturate (DA) resistance and assess livestock owner's perception of trypanocidal drug use. Four Peasant Associations (PAs) were purposively selected and the cattle randomly sampled in each PAs. At the beginning of the study (t₀), 106 bovines positive for trypanosomes by the haematocrit centrifugation technique (HCT) and 119 negative control animals were recruited for six months follow-up using HCT, 18S-PCR-RFLP, DpnII-PCR-RFLP and microsatellite analysis. Prevalence of trypanosomosis was 18.1% based on the HCT technique and the mean PCV value was 23.6 ± 5.1% for the 587 sampled cattle. Out of the 106 HCT positive, 64 (60.4%) were positive for the presence of trypanosomes using the 18S-PCR-RFLP. Species detection showed 38 (59.4%) Trypanosoma congolense savannah, 18 (28.1%) Trypanosoma vivax, 5 (7.8%) Trypanosoma theileri and 3 (4.7%) T. congolense Kilifi. Among the T. congolense savannah samples, 31 (81.6%) showed a DA resistant RFLP profile, 2 (5.3%) a mixed profile and 5 did not amplify using the DpnII-PCR-RFLP. A positive HCT had a significant effect on PCV (p < 0.001) with the mean PCV value equal to 24.4 ± 0.2% in the absence of trypanosomes and to 20.9 ± 0.3% in the presence of trypanosomes. PCV increased significantly (p < 0.001) with 4.4 ± 0.5% one month after treatment. All T. congolense savannah type were analyzed using microsatellite markers TCM1, TCM3 and TCM4. The main events were new infections (40.0%) and relapses (37.5%) with cures lagging at 22.5%. In 10 purposively selected PAs a semi-structured questionnaire was used. The average herd size was the highest in Abelti PA (6.7 ± 1.8 TLU) and the mean herd size was statistically different (p = 0.01) in the 10 PAs. Trypanosomosis was designated as the main disease affecting cattle by 97% of the respondents. DA was used by 95.5% of the farmers though more than half of them (51.9%) were not familiar with isometamidium (ISM). There was a trend to overdose young small animals and to underdose large ones. Oxen were treated very frequently (nearly 20 times/year) and calves almost never. To improve the situation in the Ghibe valley, extension messages should be delivered to promote a rational drug use, improved livestock management and the application of strategic vector control methods.     

The serological response against foot and mouth disease virus elicited by repeated vaccination of dairy cattle

In Israel, cattle are annually vaccinated against foot and mouth disease (FMD). If infections with FMD virus occur in dairy farms it mainly involves heifers and calves, while older dairy cows seldom become infected. We hypothesized that this difference in susceptibility between adult cows and the young heifers and calves is due to stronger and more stable immune response elicited by multiple vaccinations. In order to test this hypothesis, 99 dairy cattle, divided into six groups according to number of prior vaccinations, were annually vaccinated with a trivalent vaccine (A, O and Asia-1) and followed during two consecutive years. In total 988 sera were sampled at 11 time points. Virus neutralization tests (VNT) were performed in order to determine the neutralizing antibody titers (NAT) against the vaccine homologous serotypes: O-4625, O-Manisa, Asia-1-Shamir and the heterologous serotype A-Turkey-20/2006. A similar NAT pattern was observed to all serotypes and therefore statistical analysis was restricted to O-4625 serotype. In the ‘high vaccination’ groups (cows that were vaccinated at least four times before the study), high NAT were found on the beginning of the trial and no or only a mild increase of NAT was observed following further vaccinations. Additionally, in the ‘high vaccination’ groups, the percentage of cows that had a NAT higher than 2.0 (log₁₀) by the end of the 1st year was significantly higher than in the ‘low vaccination’ groups (cows vaccinated only three times or less before the study). We conclude that starting from the 5th vaccination, the NAT increase following vaccination is mild and NAT are persistent, suggesting reduction of the frequency of routine vaccination after multiple vaccinations is possible.     

Interpretation of the larval immersion test with ivermectin in populations of the cattle tick Rhipicephalus (Boophilus) microplus from Colombian farms

Interpreting in vitro bioassays used to determine resistance against acaricides in Rhipicephalus microplus can be challenging without parallel in vivo studies that assess for lost efficacy. The larval immersion test (LIT) is currently the most widely used bioassay to detect ivermectin resistance. The objective of this study was to compare results of the LIT and a field trial using ivermectin in naturally infested cattle. Criteria to consider ticks as resistant with the LIT were based on discriminating doses (DD) and the ratio of lethal concentration (LC) in test populations over the LC of the susceptible Deutch strain, known as the resistance ratio (RR). Ticks were collected from 4 farms, two where ivermectin provided good control of tick infestations and two that claimed lack of efficacy. In two farms where administration of a long-acting ivermectin formulation reduced body tick counts to 45 and 25% of the initial counts at 10-days post-treatment, the RR₅₀ and RR₉₉ were approximately 6 and 20, respectively. The LC50 value approximated the DD for the two farms with claimed resistance, suggesting that about half of the population in each farm was resistant. These LIT values are equal to those reported for the most resistant ticks, which supports the use of the LIT to predict control failure in field situations. The two farms where ivermectin provided good control of tick infestations had LC₅₀s similar to the susceptible strain, although for one farm the LC₉₉ and RR₉₉ suggested incipient resistance.     

Evaluation of the Cell-Dyn 3500 Haematology Analyser for Bovine Blood

A complete blood count provides critical information for disease diagnosis as well as prophylaxis in herd health programmes. During the last 30 years, automated haematology analysers have increasingly replaced microscopic methods. Because most haematology analysers are made for human blood, adjustments are required for the examination of blood from domestic animal species. A total of 399 blood samples, collected from cows immediately prior to parturition to 5 days post partum, were analysed using the blood analyser Cell-Dyn 3500 (Abbott Diagnostica, Delkenheim, Germany). Results of erythrocyte, platelet and leucocyte counts as well as haematocrit were compared with results obtained using reference methods. The two parameters, carry-over and within-batch precision, were within the tolerated ranges. High correlations were calculated for erythrocytes (r=0.859), leucocytes (r=0.960), haematocrit (r=0.968) neutrophils (r=0.973), eosinophils (r=0.876) and lymphocytes (r=0.802). Moderate correlations were calculated for platelets (r=0.706) and monocytes (r=0.578) whereas no meaningful correlation could be established for basophilic granulocytes. Correspondence and offprint requests to: Dr Ulrich Bleul, Klinik für Fortpflanzungskunde, Universit?t Zürich, Winterthurerstrasse 260, 8057 Zürich, Switzerland.