Changes in peripheral blood leucocyte counts and subpopulations after experimental infection with BVDV and/or Mannheimia haemolytica
ABSTRACT Leucocyte counts and subpopulations were studied in peripheral blood from calves experimentally infected in the respiratory tract with either bovine virus diarrhoea virus (BVDV) or Mannheimia haemolytica (Mh), or with a combination of both agents (BVDV/Mh). A non-inoculated control group was included. Peripheral blood samples were obtained for total leucocyte counts, and for neutrophil, lymphocyte and monocyte counts. The numbers of blood lymphocytes expressing the surface antigens CD4, CD8, WC1, B and IL-2R were analysed using flow cytometry. The results showed that BVDV inoculation induced a significant decrease in total leucocyte counts and in neutrophil and lymphocyte numbers, while Mh inoculation induced significant increases in total leucocyte counts and neutrophils, while the lymphocyte count decreased. In the BVDV/Mh group, the total leucocyte count and the lymphocyte numbers decreased significantly. In this group, the lymphocyte numbers remained on a very low level throughout the rest of the study. The numbers of CD4+, CD8+ and WC1+ lymphocytes decreased significantly compared with before inoculations mainly in the BVDV and BVDV/Mh groups. The drops were most pronounced in the BVDV/Mh group. The numbers of B+ lymphocytes and IL-2R+ cells did not change significantly.
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ABSTRACT: This experimental study was done on a total of 40 male lambs with the objectives of developing experimental vaccines from Mannheimia haemolytica serotypes A2 and A7 that express iron regulated outer membrane protein and in vivo evaluation of their efficacy. Lambs were categorized in to four experimental groups and vaccinated with 1 ml of vaccine containing 5 × 108 CFU/ml. Group 1 was vaccinated with M. haemolytica A2, group 2 with A7, group 3 with serotype A2 and A7 combination, and group 4 received saline as control. They were challenged intratracheally by the respective homologous serotype after 35 days of vaccination. Post challenge clinical investigation showed that significant higher rate of morbidity was seen in control group which was demonstrated by raised rectal temperature (by 0.5-1°C) and respiratory signs. From the total of 26 lambs challenged with live M. haemolytica A2 and A7, 6 (23.1%) and 4 (15.3%) lambs were found dead and sick, respectively. Higher mortality and morbidity were observed in unvaccinated control group; however, lesser was recorded in combined vaccinated group. Lung lesions of variable severity were observed in 13 (50.0%) lambs following challenge. From vaccinated groups, 5 (27.8%) lambs were found to have a +1 lung lesion score. All of the lambs in unvaccinated control group had scores between +2 and +3. There was a statistically significant difference (p < 0.05) between control and vaccinated groups, while no statistically significant difference (p > 0.05) was seen among vaccinated groups concerning lung lesion scores. Furthermore, the respective serotypes of M. haemolytica were successfully re-isolated from pneumonic lungs at a mean titre range of 102.2 – 108.1 CFU/g. In conclusion, lambs which received combined vaccine confer relatively good protective efficacy than M. haemolytica A2 or A7 vaccinated groups. Therefore, further study should be done on evaluation of antibody titer at different time points.African journal of microbiology research 03/2014; 8(11):1237-1244. DOI:10.5897/AJMR2013.6371 · 0.54 Impact Factor
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ABSTRACT: The objective of this study was to compare the mRNA expression of Toll-like receptors (TLR3 and TLR7), and costimulatory molecules involved in activation of lymphocytes and antigen presenting cells (CD80, CD86, CD28, and CD40L) after experimental infection of beef calves with low or high virulence noncytopathic (ncp) bovine viral diarrhea virus (BVDV) strains. Thirty BVDV-naïve, beef calves were intranasally inoculated with low (LV; n = 10, SD-1) or high (HV; n = 10, 1373) virulence ncp BVDV or with BVDV-free cell culture medium (Control, n = 10). Calves were euthanized on day 5 post-inoculation and tracheo-bronchial lymph node (TBLN) and spleen samples were collected for mRNA expression through quantitative-RT-PCR. Levels of mRNA for TLR3 and TLR7 were increased in spleen of HV group (P < 0.05), but not in LV group, compared to the control group. Expression of CD86 mRNA was up-regulated in TBLN of both LV and HV groups (P < 0.05). A significant up-regulation of CD80 mRNA was observed in TBLN for LV calves (P < 0.05), but not for HV calves. In conclusion, experimental inoculation with high virulence BVDV-2 1373 stimulated the expression of TLR3, TLR7 and CD86 in spleen and TBLN on day 5 post infection. In contrast, experimental challenge with the low virulence BVDV-1 SD-1 uniquely resulted in up-regulation of both CD80 and CD86 in TBLN samples on day 5 post infection. The observed differential expression during acute infection with high or low virulence BVDV might reflect differences in immune activation by these strains, which could be associated with differences in genotype and/or virulence.Veterinary Research Communications 08/2014; DOI:10.1007/s11259-014-9613-2 · 1.36 Impact Factor