A. Pini

Plasma levels of TNF-α, IFN-γ, IL-4 and IL-10 during a course of experimental contagious bovine pleuropneumonia

BackgroundContagious Bovine Pleuropneumonia (CBPP), caused by Mycoplasma mycoides subsp. mycoides, is widespread in sub-Saharan Africa. The current live vaccine T1/44 has limited efficacy and occasionally leads to severe side effects in the animals. A better understanding of the immune responses triggered by Mycoplasma mycoides subsp. mycoides and their role in disease progression will help to facilitate the design of a rational vaccine. Currently, knowledge of cytokines involved in immunity and immunopathology in CBPP is rather limited. The aim of this study was to characterize the in vivo plasma concentrations of the cytokines TNF-α, IFN-γ, IL-4, IL-10 and the overall role of CD4+ T cells in the development of cytokine levels during a primary infection. Plasma cytokine concentrations in two groups of cattle (CD4+ T cell-depleted and non-depleted cattle) experimentally infected with Mycoplasma mycoides subsp. mycoides were measured and their relationship to the clinical outcomes was investigated.ResultsPlasma cytokine concentrations varied between animals in each group. Depletion of CD4+ T cells did not induce significant changes in plasma levels of TNF-α, IL-4, and IL-10, suggesting a minor role of CD4+ T cells in regulation or production of the three cytokines during the time window of depletion (1-2 weeks post depletion). Unexpectedly, the IFN-γ concentrations were slightly, but statistically significantly higher in the depleted group (p < 0.05) between week three and four post infection. Three CD4+ T cell-depleted animals that experienced severe disease, had high levels of TNF-α and IFN-γ. Only one severely diseased non-depleted animal showed a high serum concentration of IL-4 post infection.ConclusionsComparison of most severely diseased animals, which had to be euthanized prior to the expected date, versus less severe diseased animals, irrespective of the depletion status, suggested that high TNF-α levels are correlated with more severe pathology in concomitance with high IFN-γ levels.

Characterization of the in vitro core surface proteome of Mycoplasma mycoides subsp. mycoides, the causative agent of contagious bovine pleuropneumonia §

Contagious bovine pleuropneumonia (CBPP), caused by Mycoplasma mycoides subsp. mycoides (Mmm) is a severe cattle disease, present in many countries in sub-Saharan Africa. The development of improved diagnostic tests and vaccines for CBPP control remains a research priority. Polyacrylamide gel electrophoresis and mass spectrometry were used to characterize the Triton X-114 soluble proteome of nine Mmm strains isolated from Europe or Africa. Of a total of 250 proteins detected, 67 were present in all strains investigated. Of these, 44 were predicted to be lipoproteins or cytoplasmic membrane-associated proteins and are thus likely to be members of the core in vitro surface membrane-associated proteome of Mmm. Moreover, the presence of all identified proteins in other ruminant Mycoplasma pathogens were investigated. Two proteins of the core proteome were identified only in other cattle pathogens of the genus Mycoplasma pointing towards a role in host-pathogen interactions. The data generated will facilitate the identification and prioritization of candidate Mycoplasma antigens for improved control measures, as it is likely that surface-exposed membrane proteins will include those that are involved in host-pathogen interactions.

Laboratory tests for evaluating the level of attenuation of bluetongue virus

One of the most important steps when preparing a live attenuated vaccine is the assessment of the level of attenuation in target animals. It is costly and time consuming as it requires, on each occasion, a large number of susceptible animals and contained accommodation. This study assessed the consistency of the bovine foetal aorta endothelial (BFA) cell line and newborn mice for evaluating the attenuation level of BTV4, BTV9 and BTV16 Italian field isolates. Following serial passages in BHK(21c13) or Vero cell cultures, BTV attenuated clones demonstrated a reduced replication capability in the BFA cells compared to the homologous virulent strains. Similarly, following intracerebral inoculation, the attenuated clones were completely innocuous to newborn mice contrary to the homologous virulent strains which killed all animals within 10 days. Vaccines produced with the BTV9 or BTV4 attenuated clones were safe, immunogenic and capable of preventing clinical symptoms and viraemia in sheep following challenge with homologous virulent virus. The two assays may be valuable indicators of the gradual changes occurring in the BTV population leading to virus attenuation, they can predict the safety of a BTV attenuated vaccine and, in turn, reduce the number of sheep and cattle required to assess the level of attenuation attained.

Molecular detection of Nigerian field isolates of Mycoplasma mycoides subsp. mycoides as causative agents of contagious bovine pleuropneumonia

Abstract Contagious bovine pleuropneumonia (CBPP) is a highly contagious respiratory disease affecting cattle and is widely distributed in the sub-Saharan Africa. The objective of this study was to detect Mycoplasma mycoides subspecies mycoides (Mmm) the causative agent of CBPP from 90 cattle at slaughter using polymerase chain reaction-Restriction fragment length polymorphism. In this study, 450 samples suggestive of CBPP in Maiduguri, Yola and Gombe township abattoirs were processed according to standard protocols. The isolation rate was found to be 3.33% and percentage of identification with PCR-RFLP yielded 1.56%. Subsequently, QIAxcel revealed molecular size of 574 bp for Mycoplasma mycoides subcluster. Further analysis of PCR amplicons with restriction digestion, confirmed the presence of Mmm 16 S rRNA of CAP 21 genomic region with molecular sizes of 180 bp and 380 bp. Thus, the 380 bp fragments delineated Mmm from Mycoplasma mycoides subsp. capri. Three isolates (BL5, BL6 and AL1) were from lungs and four from pleural fluids (APF2, APF8A, APF8B and APF9) were isolated and identified, while a vaccine strain T1/44 was re-detected along with the field isolates. No sample from Gombe had Mmm. In conclusion, the findings of this study have detected the presence of Mmm as causative agent of CBPP. Measures such as surveillance, quarantine and vaccination are hereby recommended for the control of CBPP in Nigeria.