Challenge Of Calves Research Articles

Social networks respond to a disease challenge in calves

Changes in network position and behavioral interactions have been linked with infectious disease in social animals. Here, we investigate the effects of an experimental disease challenge on social network centrality of group-housed Holstein bull dairy calves. Within group-housed pens (6/group) calves were randomly assigned to either a previously developed challenge model, involving inoculation with Mannheimia haemolytia (n = 12 calves; 3 calves/group) or a control involving only saline (n = 12 calves; 3 calves/group). Continuous behavioral data were recorded from video on pre-treatment baseline day and for 24 h following inoculation to describe social lying frequency and duration and all active social contact between calves. Mixed-model analysis revealed that changes in network position were related to the challenge. Compared to controls, challenged calves had reduced centrality and connectedness, baseline to challenge day. On challenge day, challenged calves were less central in the directed social contact networks (lower degree, strength and eigenvector centrality), and initiated contact (higher out-degree) with more penmates, compared to healthy calves. This finding suggests that giving rather than receiving affiliative social contact may be more beneficial for challenged calves. This is the first study demonstrating that changes in social network position coincide with an experimental challenge of a respiratory pathogen in calves.

Immune response to Neospora caninum native antigens formulated with immune stimulating complexes in calves

The aim of this study was to compare the immune responses to live Neospora caninum tachyzoites and N. caninum native antigens formulated with immune stimulating complexes matrix (ISCOM-matrix) in calves. Fifteen calves were used in this study: 3 were intravenously inoculated with 1×108 live tachyzoites (Group A), 3 were inoculated twice with N. caninum native antigens formulated with ISCOMs (Group B); 3 with N. caninum native antigens in phosphate-buffered saline (PBS) (Group C); 3 received ISCOM-matrix (ISCOMs without antigen) (Group D) and 3 were negative controls receiving PBS (Group E). The last four groups were inoculated subcutaneously. The specific total IgG and its subtypes were analyzed by an indirect enzyme-linked immunosorbent assays (ELISAs) and by Western blot. IFN-γ levels in plasma was quantified using a commercial kit. All calves were challenged intravenously with 1×108 live tachyzoites at week 11 after receiving the first dose. Parasitemia was assessed in plasma samples by semi-nested PCR. Neospora-specific antibodies were detected in animals from Groups A and B in the week 2 after inoculation. The ELISA OD values were higher in Group B compared with Group A from weeks 6 to 11 (P<0.05). Analysis of the subisotype specific antibodies in experimentally infected calves revealed a predominant IgG2 response; however, a predominant IgG1 response was observed in animals inoculated with N. caninum native antigens formulated with ISCOM-matrix. Control calves remained seronegative until challenge infection. The pattern of bands by Western blot was similar when testing sera from animals in Groups A and B. The levels of IFN-γ production after respective immunization schedules were similar between Groups A and B. Neospora-DNA was detected in plasma samples shortly after intravenous challenge in calves from all groups including those receiving the experimental vaccine formulation. The duration of the parasitemia was similar in all groups.

The effect of zinc oxide and elemental zinc boluses on the concentrations of Zn in serum and faeces, and on providing protection from natural Pithomyces chartarum challenge in calves

AIM: To investigate the efficacy of intra-ruminal Zn boluses as aids in providing protection from natural Pithomyces chartarum challenge in calves. METHODS: Sixty-two calves (mean weight 187 (SEM 3.25) kg) were divided into three groups. Commencing on Day 0, they received either a proprietary bolus containing 83% ZnO (ZnO group), a prototype Zn bolus containing 88% elemental Zn (Zn group), or remained untreated (Control group). Concentrations of Znin serum and faeces were measured weekly between Days 6 and 34, activities of gamma-glutamyl transferase (GGT)in serum on Days -8, 20, 34 and 41, and faecal spore counts between Days 13 and 41. RESULTS: Between Days 6 and 34, mean concentrations of Zn in serum increased in both Zn treatment groups compared with Controls (p<0.001), but were lower in Zn than ZnO animals between Days 6 and 28 (p=0.05). Concentrations of Zn in faeces were increased in both groups following treatment with Zn. Mean concentrations of Zn in faeces in ZnO animals was higher than Zn animals on Days 13 and 20 (p<0.001), but decreased by Day 34, whereas for Zn animals they were still elevated on Day 34. Faecal spore counts were 354,000 and 183,000 on Days 13 and 20, respectively, 610,500 on Day 28, and 115,500 spores/g on Day 34. There were no clinical signs of facial eczema, but based on the activities of GGT on Day 41, 17/20 (85%) Controls were moderately or severely affected (GGT >250 IU/L) compared with 1/21 (5%) ZnO and 3/21 (14%) Zn animals. Mean activities of GGT on Day 41 for ZnO and Zn animals were not different (35 (95% CI=23-54) and 54 (95% CI=32-92) IU/L, respectively; p=0.18), but were below those of the Controls (502 (95% CI 296, 850) IU/L), confirming efficacy of both bolus treatments. In both ZnO and Zn animals, there was no significant relationship between concentration of Zn in serum and activity of GGT, but in Zn animals there was a significant relationship between the concentration of Zn in faeces and activity of GGT 21 days later. The regression equation y=2.136- 0.002197x (where y is log10GGT activity, and x the concentration of Zn in faeces) provided an estimate of the threshold level of concentration of Zn in faeces. CONCLUSION: The study confirmed efficacy of elemental Zn boluses in providing protection from natural P. chartarum challenge in young cattle.

Vaccination with recombinant Mycobacterium avium subsp. paratuberculosis proteins induces differential immune responses and protects calves against infection by oral challenge

We previously reported the in vitro cellular immune responses to recombinant antigens (rAgs) of Mycobacterium avium subsp. paratuberculosis (MAP). Here we report the differential immune responses and protective efficacy of four rAgs of MAP (85A, 85B, 85C, and superoxide dismutase (SOD)) used with two adjuvants (monophosphoryl lipid A (MPLA) containing synthetic trehalose dicorynomycolate, cell wall skeleton (MPLA) and bovine IL-12), against MAP challenge in calves. Group I was administered the four rAgs with MPLA and IL-12. Group II was administered the four rAgs and MPLA. Group III received MPLA and IL-12, and Group IV MPLA. rAgs induced significant lymphoproliferative responses in vaccinated animals (Groups I and II). All the rAgs induced significant IFN-gamma production from 11 to 23 wk after primary vaccination (APV), except for SOD. Significant increases were noted in CD3(+), CD4(+), CD8(+), CD21(+), CD25(+), and gammadelta(+) cells against all four rAgs in vaccinated animals. rAg-specific expression of IL-2, IL-12p40, IFN-gamma and TNF-alpha was significantly higher in the two vaccinated groups. Culture results found 4/8 animals in Group I, 3/8 animals in Group II, and 3/4 animals in Groups III and IV were positive for MAP in one or more tissues. Among the seven positive animals in Groups I and II, all but one had had <10CFU. Isolation was confined to one tissue in these animals, except in one animal in which MAP was isolated from two tissues. In the control groups (III and IV), MAP was cultured from up to five different tissues with >250CFU. Preliminary data from this study indicates that all four rAgs induced a good Th1 response and conferred protection against MAP infection in calves.

Influence of Host Immunity on Parasite Diversity inTheileria parva

We examined the influence of host immunity on the genotypic diversity of the intracellular transforming cattle parasite Theileria parva. By tracking the emergence of discrete parasite genotypes in an animal challenged with a bulk stabilate following immunization with its major component clone, we observed a profound modulation of genotypic frequencies in the breakthrough schizont population. In particular, no incidences of the immunizing clone were observed and a progressive decline was apparent in the relatedness of breakthrough genotypes to it. These observations were reflected in the genotypic profile of transmissible parasite stages that emerged in the erythrocyte fraction of the animal and in parasite progeny generated by tick pickup. In a separate experiment, genotypic profiles of breakthrough parasite populations were observed to vary between unrelated immune animals selected on the basis of the major histocompatibility complex (MHC) class I phenotype, a known determinant of the specificity of the immune response. Furthermore, immunization and challenge of calves with molecularly distinct but cross-protective parasite populations revealed that infection results in transmissible erythrocyte forms in spite of a protective immune response. These observations suggest that immunity does not prevent transmission of challenge parasites and that its impact on the parasite at a population level is influenced by herd MHC diversity.

Genetic variation and cross-reactivity of Clostridium septicum alpha-toxin

Clostridium septicum alpha-toxin genes were sequenced with the polymerase chain reaction (PCR) products amplified from DNAs of 25 C. septicum strains, and were classified into 10 patterns. Alpha-toxins were purified from the culture supernatant of four C. septicum strains (strains No. 44, Kagoshima 8, Mie and Tokachi) which were specially chosen from patterns of the deduced amino acid sequences. The molecular weights of the alpha-toxins were not different according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. However, the isoelectric points between the alpha-toxins of No. 44 and Tokachi strains differed markedly. Cross-neutralization tests were performed with purified alpha-toxins and antitoxins in mice and in Vero cells. Each antitoxin showed roughly the same titers against the four alpha-toxins in mice and completely identical titers against these in Vero cells. Calves immunized with toxoid prepared from the culture supernatant of No.44 strain were challenged by exposure to spores of Mie strain. The toxoid conferred protection against the challenge in calves. From these results, although genetic variation has been observed within the C. septicum alpha-toxin gene, C. septicum strains toxoid of strain No.44 induces protective immunity against exposure to C. septicum that produce other subtypes of alpha-toxin containing several different amino acid residues.

Decreased Fecal Shedding of Salmonella Newport through Vaccination

Foodborne enteric pathogens, such as Salmonella and Escherichia coli, have met with increased scrutiny by consumers, the food industry and government regulatory agencies. One of the primary food safety initiatives today is to prevent the spread of bacterial enteric pathogens from the farm to the table. Controlling these pathogens at the farm level is one of many strategies being pursued to ensure the safety of our food supply. One such approach in reducing consumer health risks associated with Salmonella and E. coli has focused on preventing intestinal colonization and fecal shedding of these pathogens in meat producing animals. Unfortunately, other than for improving general hygiene and reducing oral-fecal transmission, the control of these pathogens has met with limited success, leaving the producer vulnerable and often bewildered as to "what to do". The following study evaluates the use of a novel vaccine composition to prevent intestinal colonization of Salmonella in a controlled Salmonella Newport challenge in calves.

The Use of Bovine Serum Protein as an Oral Support Therapy Following Coronavirus Challenge in Calves

The objective of this experiment was to investigate the therapeutic efficacy of a supplemental bovine serum protein blend fed to calves challenged with virulent coronavirus. Twelve Holstein bull calves (approximately 3 wk of age) were allocated by initial body weight to Control (n = 5) and treated (n = 7) groups. On d 0, all calves were orally challenged with 1 × 107 plaque forming units of virulent coronavirus isolate. Infection was allowed to progress for 24h before treatment was started. On d 1, treated calves began receiving 160g of dry bovine serum powder (16g IgG) mixed into milk replacer powder (67g) at both an a.m. and p.m. feeding. Control calves received only milk replacer powder (227g) at both feedings. Response to coronavirus challenge and dietary treatment was monitored prior to a.m. and p.m. feeding by the collection of multiple clinical measures. Fecal consistency was decreased by coronavirus challenge but was not affected by dietary treatment. Mean daily rectal temperature and heart rate were not affected by dietary treatment. Average packed cell volume was higher in treated calves than in control (35.0 and 27.0%). Coronavirus challenge resulted in an immediate increase in respiration rate, decreasing by d 7. Control calves tended to have a greater average respiration rate compared with treated (28.7 vs. 26.8 breaths/min). Treated calves had a higher average feed intake than control (0.57 vs. 0.44 kg/d). These data suggest that bovine-serum supplemented milk replacer may decrease the severity of disease in young calves exposed to coronavirus.

Efficacy of a BVD Type I MLV Vaccine Against a Virulent BVD Type II Experimental Challenge in Young Calves

The objective of this study was to determine the efficacy of a vaccine containing modified-live bovine viral diarrhea virus Type I (BVD1) against a highly virulent BVD Type II (BVD2) challenge in calves.

Efficacy of an Inactivated BRSV Vaccine Against a Virulent BRSV Experimental Challenge in Young Calves

The objective of this study was to determine the efficacy of a vaccine containing inactivated Bovine Respiratory Syncytial Virus (BRSV) against a highly virulent BRSV challenge in calves.

Evaluation of immunization with gut membrane glycoproteins of Ostertagia ostertagi against homologous challenge in calves and against Haemonchus contortus in sheep

Peanut and ConA lectins were used as ligands to isolate glycoproteins from detergent extracts of adult Ostertagia ostertagi membranes. As judged by their profiles following SDS-PAGE, these fractions closely resembled the equivalents from Haemonchus contortus which are derived from the nematode intestinal cell microvillar membranes and which are highly protective when used as antigens. Groups of calves were immunized with the peanut and ConA binding fractions of Ostertagia, either as separate or pooled antigens mixed with QuilA as adjuvant. All calves, including controls immunized with adjuvant only, were challenged with a single dose of infective Ostertagia larvae and faecal egg counts were monitored for 5 weeks. In two experiments where the antigen fractions were pooled, moderate (30-50%), but statistically significant reductions in egg output were observed, but the number of worms was not diminished. No significant protection was observed in a third trial where groups of calves were immunized with peanut or ConA binding proteins given separately. Two further trials were conducted in sheep immunized with the same Ostertagia fractions but challenged with Haemonchus. Irrespective of whether they were administered separately or together, the Ostertagia antigens cross protected efficiently against Haemonchus reducing egg counts by between 81% and 97% and worm numbers by between 57% and 84%.

Avaliação de uma vacina oleosa contra a colibacilose bovina utilizando os antígenos K99-F41 semipurificados

Os antígenos K99-F41 foram extraídos da amostra de Escherichia coli B41 por aquecimento e semi-purificados pela precipitação com sulfato de amônio e tratamento com desoxicolato de sódio (DOC). Os antígenos semi-purificados foram utilizados na produção de uma vacina oleosa contra a colibacilose bovina. Foram preparadas vacinas contendo em cada dose 1.500 HU (Unidades Hemaglutinantes), 750 HU e 380 HU. A eficiência da vacina foi avaliada através do ensaio de imunodifusão dupla, ensaio imunoenzimático (ELISA) e por um desafio, em que a amostra de Escherichia coli virulenta foi inoculada nos bezerros nascidos de vacas vacinadas e não vacinadas. Observamos que a vacina contendo 750 HU foi a que melhor induziu a produção de anticorpos nas vacas vacinadas, e que estes mostraram-se protetores, uma vez que os bezerros nascidos de vacas vacinadas e que mamaram o colostro, nada sofreram no desafio. Não se verificou nenhum efeito colateral nas vacas vacinadas.