A nano particle vector comprised of poly lactic-co-glycolic acid and monophosphoryl lipid A and recombinant Mycobacterium avium subsp paratuberculosis peptides stimulate a pro-immune profile in bovine macrophages.

AIMS: We evaluated the potential of a nanoparticle (NP) delivery system to improve methods of delivery of candidate peptide-based vaccines for Paratuberculosis in cattle. METHODS AND RESULTS: Peptides derived from Mycobacterium avium subsp. paratuberculosis (Map), and the pro-inflammatory monophosphoryl lipid A (MPLA) were incorporated in polymeric NPs based on poly (d,l-lactide-co-glycolide) (PLGA). The PLGA/MPLA NPs carriers were incubated with macrophages to examine their effects on survival and function. PLGA/MPLA NPs, with and without Map antigens, are efficiently phagocytized by macrophages with no evidence of toxicity. PLGA/MPLA NP formulations did not alter the level of expression of MHC I or II molecules. Expression of TNFα and IL12p40 was increased in Map-loaded NPs. T-cell proliferation studies using a model peptide from Anaplasma marginale demonstrated that a CD4 T-cell recall response could be elicited with macrophages pulsed with the peptide encapsulated in the PLGA/MPLA NP. CONCLUSIONS: These findings indicate PLGA/MPLA NPs can be used as a vehicle for delivery and testing of candidate peptide-based vaccines. SIGNIFICANCE AND IMPACT OF THE STUDY: These results will assist on more in depth studies on PLGA NP delivery systems that may lead to the development of a peptide-based vaccine for cattle.

Pathogenesis of Photobacterium damselae subspecies infections in sea bass and sea bream.

Photobacterium damselae is a Gram negative bacterium causes photobacteriosis, a worldwide septicemic disease in aquaculture including sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata). The pathogenicity of bacterial subspecies and the disease pathological changes in natural and experimental infections have thus far yielded inconsistency of effective preventive measures. This study aimed to represent a comprehensive analysis of the potential pathogenic capacities of the two subspecies of P. damselae in cultured sea bass and sea bream in the Northwestern region of Egypt. Diseased 321 sea bass and 257 sea bream, in addition to 99 healthy sea bass fingerlings were sampled from three farms located along the Mediterranean Sea. P. damselae subspecies were isolated from diseased fish and characterized using bacteriological, molecular, and antimicrobial susceptibility methods. Healthy fish were challenged by a virulent P. damselae subsp. piscicida, monitored for disease signs and mortality, and the histopathological abnormalities and hematological disorders were carried out. Clinical signs and gross lesions in naturally infected sea bass and sea bream showed great similarities with absence of a subspecies-specific characteristic sign or lesion. The two subspecies were recovered through the entire year from individual fish sample, suggests a coexistence of two subspecies endemic infection. In diseased sea bass, 38.32% and 16.20% were positive for P. damselae subsp. piscicida and subsp. damselae, respectively. However in diseased sea bream, 44.47% and 26.46% were positive for P. damselae subsp. piscicida and subsp. damselae, respectively. High mortalities and devastating clinicopathologic abnormalities represented by sever clinical signs, hematological disorders and histological abnormalities strengthen the pathogenicity of P. damselae subspecies in the two fish species and therefore, a vaccination strategy against both subspecies should be taken into account.

Prevalence of Bovine Tuberculosis in Egyptian Cattle and the Standardization of the Interferon-gamma Assay as an Ancillary Test.

Bovine tuberculosis (bTB) caused primarily by Mycobacterium bovis continues to cause significant losses in the cattle industry and is a major public health problem. Despite its worldwide application, the IFN-γ assay has not been applied in Egypt. The aim of this study was to determine the appropriate cut-off value of IFN-γ assay to complement the skin test screening in Egypt. The relative sensitivity (Ser ) of PPD and antigen cocktail-based IFN-γ assays (IFN-γ-BA and IFN-γ-EC) was analysed retrospectively, relative to bTB confirmatory tests (culture and PCR), using single cervical tuberculin (SCT) test reactors during 2011-2013. The absolute specificity (Sp) was studied using blood samples collected from cattle from one bTB-free herd. Analysis of the bTB database-generated sheets indicates the infection rate had decreased from 2009 to 2012 and then increased in 2013. The disease is concentrated in the Egyptian Nile Delta and Valley relative to elsewhere in the country. The cut-offs for IFN-γ-EC assay could be optimized to provide higher sensitivity, comparable to cut-offs for IFN-γ-BA assay. Data analysis suggests (PPDbOD  > 0.1, PPDbOD  - NILOD  > 0.05 and PPDbOD  > PPDaOD ) and (ECOD  - NILOD  ≥ 0.1) cut-off strategies to get optimal IFN-γ-BA and IFN-γ-EC assays results respectively. To our knowledge, this is the first report describing the prevalence of bTB in cattle in Egypt and pointing out the appropriate cut-off criteria to optimize IFN-γ assay as a routine ancillary test for diagnosis of bTB in Egypt.