As a novel coronavirus first reported by Saudi Arabia in 2012, the Middle East respiratory syndrome coronavirus (MERS-CoV) is responsible for an acute human respiratory syndrome. The virus, of 2C beta-CoV lineage, expresses the dipeptidyl peptidase 4 (DPP4) receptor and is densely endemic in dromedary camels of East Africa and the Arabian Peninsula. MERS-CoV is zoonotic but human-to-human transmission is also possible. Surveillance and phylogenetic researches indicate MERS-CoV to be closely associated with bats' coronaviruses, suggesting bats as reservoirs, although unconfirmed. With no vaccine currently available for MERS-CoV nor approved prophylactics, its global spread to over 25 countries with high fatalities highlights its role as ongoing public health threat. An articulated action plan ought to be taken, preferably from a One Health perspective, for appropriately advanced countermeasures against MERS-CoV.

Campylobacter is one of the major foodborne pathogens causing bacterial gastroenteritis worldwide. The immune response of broiler chickens to C. jejuni is under-researched. This study aimed to characterize the immune response of chickens to Campylobacter jejuni colonization. Birds were challenged orally with 0.5 mL of 2.4 x 108 CFU/mL of Campylobacter jejuni or with 0.5 mL of 0.85% saline. Campylobacter jejuni persisted in the ceca of challenged birds with cecal colonization reaching 4.9 log10 CFU/g on 21 dpi. Campylobacter was disseminated to the spleen and liver on 7 dpi and was cleared on 21 dpi from both internal organs. Challenged birds had a significant increase in anti-Campylobacter serum IgY (14&21 dpi) and bile IgA (14 dpi). At 3 dpi, there was a significant suppression in T-lymphocytes derived from the cecal tonsils of birds in the challenge treatment when compared to the control treatment after 72 h of ex vivo stimulation with Con A or C. jejuni. The T-cell suppression on 3 dpi was accompanied by a significant decrease in LITAF, K60, CLAU-2, IL-1β, iNOS, and IL-6 mRNA levels in the ceca and an increase in nitric oxide production from adherent splenocytes of challenged birds. In addition, on 3 dpi, there was a significant increase in CD4+ and CD8+ T lymphocytes in the challenge treatment. On 14 dpi, both pro and anti-inflammatory cytokines were upregulated in the spleen, and a significant increase in CD8+ T lymphocytes in Campylobacter-challenged birds’ ceca was observed. The persistence of C. jejuni in the ceca of challenged birds on 21 dpi was accompanied by an increase in IL-10 and LITAF mRNA levels, an increase in MNC proliferation when stimulated ex-vivo with the diluted C. jejuni, an increase in serum specific IgY antibodies, an increase in both CD4+ and CD8+ cells, and a decrease in CD4+:CD8+ cell ratio. The balanced Th1 and Th2 immune responses against C. jejuni might explain the ceca’s bacterial colonization and the absence of pathology in Campylobacter-challenged birds. Future studies on T lymphocyte subpopulations should elucidate a pivotal role in the persistence of Campylobacter in the ceca.

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Currently, there is no commercial vaccine to control  Clostridium perfringens  (CP) or necrotic enteritis – a clinically and economically devastating disease. Two chitosan-nanoparticle encapsulated CP (CNP-CP) vaccines using extracellular proteins (ECP) and cell wall proteins (CWP) were synthesized: a CNP-CP ECP + CWP vaccine (SC vaccine) and a CNP-CP ECP + CWP surface-adsorbed CWP vaccine (SCC vaccine). The experiment comprised a complete randomized design of 3 treatments replicated 5 times: SC, SCC and nonimmunized control.  Broilers orally gavaged with SC or SCC vaccine were primed and boosted with 70µg dose at 3- and 14-days post-hatch (dph). SDS-PAGE analysis revealed bands at 54.7 and 84.7 kDa in the ECP and 17 bands for CWP fraction. There were no differences in body weight gain, feed conversion ratio and mortality rate between treatments. At 17dph, serum of birds in the SC and SCC groups had higher neutralizing antibodies ( P <0.01) compared to the control group. At 17dph, there was an increase in bile anti-ECP IgA levels in the SC vaccinated birds and a non-significant increase in SCC vaccinated birds compared to control. At 17dph, bile specific anti-CP CWP IgA levels were greater ( P<0.05 ) in both immunized groups compared to control. At 17 and 21dph, serum anti-ECP and anti-CP CWP IgY levels in SC and SCC birds were comparable to the control. At 21dph, CD4 + /CD8 +  T-cell ratio in SC and SCC vaccinated groups were elevated ( P 0.01 ) compared to control. At 17dph, SC and SCC vaccinated birds had a significant reduction  (P 0.001)  in  -toxin levels in caecal contents compared to control. Caecal  -toxin levels remained reduced at 21dph  (P 0.05)  in SC birds and numerically reduced in SCC vaccinated birds compared to control. Jejunal CP load in SCC birds was significantly reduced by 1.4 Log 10  copy numbers of CP/g compared to control and no differences were observed in liver CP load between immunized and non-immunized birds. SC and SCC immunization did not alter TNF- , IL-10, iNOS, IL-6 or IL-17 mRNA expression. At 17 and 21dph, SC and SCC immunized birds demonstrated greater sera bactericidal activity compared to control. CNP-SC and CNP-SCC immunization induced specific immune response against  C. perfringens  and reduced CP colonization via oral route of administration.