MERS-CoV seronegative and seropositive camels received a single intramuscular dose of ChAdOx1 MERS, a replication-deficient adenoviral vectored vaccine expressing MERS-CoV spike protein, with further groups receiving control vaccinations. Infectious camels with active naturally acquired MERS-CoV infection, were co-housed with the vaccinated camels at a ratio of 1:2 (infected:vaccinated); nasal discharge and virus titres were monitored for 14 days. Overall, the vaccination reduced virus shedding and nasal discharge (p = 0.0059 and p = 0.0274, respectively). Antibody responses in seropositive camels were enhancedby the vaccine; these camels had a higher average age than seronegative. Older seronegative camels responded more strongly to vaccination than younger animals; and neutralising antibodies were detected in nasal swabs. Further work is required to optimise vaccine regimens for younger seronegative camels.

Rift Valley Fever virus (RVFV) causes recurrent outbreaks of acute life-threatening human and livestock illness in Africa and the Arabian Peninsula. No licensed vaccines are currently available for humans and those widely used in livestock have major safety concerns. A ‘One Health’ vaccine development approach, in which the same vaccine is co-developed for multiple susceptible species, is an attractive strategy for RVFV. Here, we utilized a replication-deficient chimpanzee adenovirus vaccine platform with an established human and livestock safety profile, ChAdOx1, to develop a vaccine for use against RVFV in both livestock and humans. We show that single-dose immunization with ChAdOx1-GnGc vaccine, encoding RVFV envelope glycoproteins, elicits high-titre RVFV-neutralizing antibody and provides solid protection against RVFV challenge in the most susceptible natural target species of the virus-sheep, goats and cattle. In addition we demonstrate induction of RVFV-neutralizing antibody by ChAdOx1-GnGc vaccination in dromedary camels, further illustrating the potency of replication-deficient chimpanzee adenovirus vaccine platforms. Thus, ChAdOx1-GnGc warrants evaluation in human clinical trials and could potentially address the unmet human and livestock vaccine needs.

Staphylococcus aureus (S. aureus) is one of the prevalent mastitis-inducing pathogens worldwide. The resistance of S. aureus to antibiotics is a common issue for dairy farms. Recently, nanoparticles (NPs) have been used for treating antibiotic-resistant bacteria. We therefore aimed to investigate the antimicrobial effect of silver and gold NPs (AgNPs and AuNPs, respectively) and the resistance developed by S. aureus as well as the toxic effects of both NPs in rats. We used 198 S. aureus strains to determine the antibacterial effects of AgNPs and AuNPs. The microdilution method was used to establish the minimum inhibitory concentrations (MICs) of both NPs. To induce resistance, 20 S. aureus strains were passaged 10 times in broth medium with sublethal doses of NPs and an additional 10 times without NPs to examine the stability of resistance. Histopathology was performed after oral administration to the rats with the study doses of 0.25, 0.5, 1, and 2 mg/kg of NPs for 30 days. The MICs of 10-nm AgNPs, 20-nm AgNPs, 10-nm AuNPs, and 20-nm AuNPs against S. aureus were 14.70 ± 1.19 μg/ml, 9.15 ± 0.13 μg/ml, 24.06 ± 2.36 μg/ml, and 18.52 ± 1.26 μg/ml, respectively. Most strains developed strong resistance when treated with 20-nm or 10-nm AgNPs, whereas only two strains were resistant to 10-nm AuNPs and three strains to 20-nm AuNPs. No cross-resistance between NPs and various antibiotics was identified in any of the adapted S. aureus strains. Organ histopathology revealed that 0.25, 0.5, and 1 mg/kg doses of AgNPs and AuNPs were not toxic to rat tissue. In contrast, a higher dose (2 mg/kg) of NPs impaired all organs tested. This study demonstrates the antibacterial effects of NPs. S. aureus strains develop resistance less frequently against AuNPs than AgNPs, and neither AuNPs nor AgNPs was toxic to rats at low doses.

Mycobacterium avium subspecies paratuberculosis ( M. ap ) is the causative agent of paratuberculosis or Johne's disease (JD) in herbivores with potential involvement in cases of Crohn's disease in humans. JD is spread worldwide and is economically important for both beef and dairy industries. Generally, pathogenic ovine strains ( M. ap -S) are mainly found in sheep while bovine strains ( M. ap -C) infect other ruminants (e.g. cattle, goat, deer), as well as sheep. In an effort to characterize this emerging infection in dromedary/Arabian camels, we successfully cultured M. ap from several samples collected from infected camels suffering from chronic, intermittent diarrhea suggestive of JD. Gene-based typing of isolates indicated that all isolates belong to sheep lineage of strains of M. ap ( M. ap -S), suggesting a putative transmission from infected sheep herds. Screening sheep and goat herds associated with camels identified the circulation of this type in sheep but not goats. The current genome-wide analysis recognizes these camel isolates as a sub-lineage of the sheep strain with a significant number of single nucleotide polymorphisms (SNPs) between sheep and camel isolates (∼1000 SNPs). Such polymorphism could represent geographical differences among isolates or host adaptation of M. ap during camel infection. To our knowledge, this is the first attempt to examine the genomic basis of this emerging infection in camels with implications on the evolution of this important pathogen. The sequenced genomes of M. ap isolates from camels will further assist our efforts to understand JD pathogenesis and the dynamic of disease transmission across animal species.

Bovine coronavirus (BCV) causes neonatal calf diarrhea (CD) and is associated with winter dysentery (WD) in adult dairy cattle. It can also be isolated from the respiratory tracts of cattle entering feedlots. Monoclonal antibodies (MAbs) specific for the hemagglutinin esterase (HE) and spike (S) surface proteins of 2 bovine enteric coronavirus (BECV) strains and two bovine respiratory coronavirus (BRCV) strains were tested against 6 BECV strains and 6 recently isolated BRCV strains, in order to characterize the antigenicity of BCV strains with varied tissue tropisms. All MAbs had high immunofluorescence (IF) titers against BECV and BRCV strains, indicative of conserved cross-reactive epitopes. In hemagglutination inhibition (HI) tests, the S-MAbs were more broadly reactive than HE-MAbs. The BRCV and CD MAbs were more broadly reactive in HI than the WD MAbs. The HA activity of the Mebus vaccine CD strain was not inhibited by any of the MAbs tested. The HI activity of BRCV strain R6 was unique among the 6 BRCV isolates. In virus neutralization assays, MAbs to the BRCV strain R4 neutralized all 6 BECV strains tested. Antigenic variation exists among both BECV and BRCV strains, but it cannot be attributed soley to the clinical origin of the strain.