Humoral Immunogenicity and Efficacy of a Single Dose of ChAdOx1 MERS Vaccine Candidate in Dromedary Camels

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

Organophosphate Insecticides Resistance in Field Populations of House Flies, Musca domestica L.: Levels of Resistance and Acetylcholinesterase Activity

The house fly, Musca domestica L., is an important medical and veterinary pest associated with humans and livestock. Management of house flies has relied extensively on chemical control. In this study, we report on the resistance of house fly field-collected populations to diazinon and fenitrothion OP insecticides in Riyadh, Saudi Arabia. The diazinon and fenitrothion median lethal dose (LD50) values against adult female M. domestica field-collected populations were significantly higher than those of the laboratory (LAB) strain. Different levels of resistance were detected in all field-collected populations toward the two OP insecticides. The resistance ratios for diazinon ranged from 62.47 to 309.78, while there were 53.08 to 261.24 for fenitrothion in the eight field-collected populations. The specific activity of acetylcholinesterase (AChE) in all field populations was significantly (p < 0.05) higher than that in the LAB strain. In vitro diazinon and fenitrothion median inhibitory concentration (IC50) values of LAB strain AChE activity were significantly (p < 0.05) lower than those for field-collected populations. This study found high levels of resistance in the house fly field-collected populations to diazinon and fenitrothion. Replacing these two insecticides and any other OPs with novel ones that have different modes of action is an urgent need in the insect-vector control programs in Riyadh, Saudi Arabia. An altered AChE enzyme of M. domestica field populations might be partially responsible for the developed resistance. Monitoring of insecticide resistance development in M. domestica populations and a better understanding of its mechanisms are needed to design operative management strategies for controlling the house flies

The prevalence of Middle East respiratory Syndrome coronavirus (MERS-CoV) infection in livestock and temporal relation to locations and seasons

Background: The Middle East respiratory syndrome (MERS) has been reported for the first time infecting a human being since 2012. The WHO was notified of 27 countries have reported cases of MERS, the majority of these cases occur in the Arabian Peninsula, particularly in Saudi Arabia. Dromedary camels are likely to be the main source of Middle East respiratory syndrome virus (MERS-CoV) infection in humans. Methods: MERS-CoV infection rates among camels in livestock markets and slaughterhouses were investigated in Saudi Arabia. A total of 698 nasal swabs were collected and examined with Rapid assay and rtRT-PCR. Ten MERS-CoV positive samples were subjected to full genomic sequencing. In addition, the sensitivity and specificity of the Rapid immunochromatographic assay (BioNote, South Korea) was evaluated as a diagnostic tool for MERS-CoV compared to rtRT-PCR. Results: The results showed a high percentage of dromedaries (56.4%) had evidence for nasal MERS-CoV infection. Phylogenetic analysis of the ten MERS-CoV isolates showed that the sequences were closely related to the other MERS-CoV strains recovered from camels and human cases. Moreover, the results showed that 195 samples were positive for MERS-CoV by rapid assay compared to 394 positive samples of rtRT-PCR, which showed low rapid assay sensitivity (49.49%) while, the specificity were found to be 100%. Conclusion: These findings indicate that these sites are a highly-hazardous to zoonotic diseases. Keywords: MERS, Slaughterhouses, Livestock markets, Saudi Arabi