Nathaniel Nyakaat Ninyio

The increasing outbreak of zoonotic diseases presents challenging times for nations and calls for a renewed effort to disrupt the chain of events that precede it. Nigeria’s response to the 2006 bird flu provided a platform for outbreak response, yet it was not its first experience with Influenza. This study describes the impact of SARS-CoV-2 on Influenza surveillance and, conversely, while the 1918 Influenza pandemic remains the most devastating (500,000 deaths in 18 million population) in Nigeria, the emergence of SARS CoV-2 presented renewed opportunities for the development of vaccines with novel technology, co-infection studies outcome, and challenges globally. Although the public health Intervention and strategies left some positive outcomes for other viruses, Nigeria and Africa’s preparation against the next pandemic may involve prioritizing a combination of technology, socioeconomic growth, and active surveillance in the spirit of One Health.

Hepatitis B is a major global health challenge. In the absence of an effective treatment for the disease, hepatitis B vaccines provide protection against the viral infection. However, some individuals do not have positive immune responses after being vaccinated with the hepatitis B vaccines available in the market. Thus, it is important to develop a more protective vaccine. Previously, we showed that hepatitis B virus (HBV) ‘a’ determinant (aD) displayed on the prawn nodavirus capsid (Nc) and expressed in Spodoptera frugiperda (Sf9) cells (namely, Nc-aD-Sf9) self-assembled into virus-like particles (VLPs). Immunisation of BALB/c mice with the Nc-aD-Sf9 VLPs showed significant induction of humoral, cellular and memory B-cell immunity. In the present study, the biophysical properties of the Nc-aD-Sf9 VLPs were studied using dynamic light scattering (DLS) and circular dichroism (CD) spectroscopy. Enzyme-linked immunosorbent assay (ELISA) was used to determine the antigenicity of the Nc-aD-Sf9 VLPs, and multiplex ELISA was employed to quantify the cytokine response induced by the VLPs administered intramuscularly into BALB/c mice (n = 8). CD spectroscopy of Nc-aD-Sf9 VLPs showed that the secondary structure of the VLPs predominantly consisted of beta (β)-sheets (44.8%), and they were thermally stable up to ~52 °C. ELISA revealed that the aD epitope of the VLPs was significantly antigenic to anti-HBV surface antigen (HBsAg) antibodies. In addition, multiplex ELISA of serum samples from the vaccinated mice showed a significant induction (p < 0.001) of IFN-γ, IL-4, IL-5, IL-6, IL-10, and IL-12p70. This cytokine profile is indicative of natural killer cell, macrophage, dendritic cell and cytotoxic T-lymphocyte activities, which suggests a prophylactic innate and adaptive cellular immune response mediated by Nc-aD-Sf9 VLPs. Interestingly, Nc-aD-Sf9 induced a more robust release of the aforementioned cytokines than that of Nc-aD VLPs produced in Escherichia coli and a commercially used hepatitis B vaccine. Overall, Nc-aD-Sf9 VLPs are thermally stable and significantly antigenic, demonstrating their potential as an HBV vaccine candidate.

Epizootics of highly pathogenic avian influenza (HPAI) have resulted in the deaths of millions of birds leading to huge financial losses to the poultry industry worldwide. The roles of migratory wild birds in the harbouring, mutation, and transmission of avian influenza viruses (AIVs), and the lack of broad-spectrum prophylactic vaccines present imminent threats of a global panzootic. To prevent this, control measures that include effective AIV surveillance programmes, treatment regimens, and universal vaccines are being developed and analysed for their effectiveness. We reviewed the epidemiology of AIVs with regards to past avian influenza (AI) outbreaks in birds. The AIV surveillance programmes in wild and domestic birds, as well as their roles in AI control were also evaluated. We discussed the limitations of the currently used AI vaccines, which necessitated the development of a universal vaccine. We evaluated the current development of AI vaccines based upon virus-like particles (VLPs), particularly those displaying the matrix-2 ectodomain (M2e) peptide. Finally, we highlighted the prospects of these VLP vaccines as universal vaccines with the potential of preventing an AI panzootic.

Chimeric virus-like particles (VLPs) have been widely exploited for various purposes including their use as vaccine candidates, particularly due to their ability to induce stronger immune responses than VLPs consisting of single viral proteins. In the present study, VLPs of the Macrobrachium rosenbergii nodavirus (MrNV) capsid protein (Nc) displaying the hepatitis B virus “a” determinant (aD) were produced in Spodoptera frugiperda (Sf9) insect cells. BALB/c mice immunised with the purified chimeric Nc-aD VLPs elicited a sustained titre of anti-aD antibody, which was significantly higher than that elicited by a commercially available hepatitis B vaccine and Escherichia coli-produced Nc-aD VLPs. Immunophenotyping showed that the Sf9-produced Nc-aD VLPs induced proliferation of cytotoxic T-lymphocytes and NK1.1 natural killer cells. Furthermore, enzyme-linked immunospot (ELISPOT)analysis showed the presence of antibody-secreting memory B cells in the mice splenocytes stimulated with the synthetic aD peptide. The significant humoral, natural killer cell and memory B cell immune responses induced by the Sf9-produced Nc-aD VLPs suggest that they present good prospects for use as a hepatitis B vaccine candidate.

Exploration of efficacious plant extracts that can reduce or inhibit Pseudomonas aeruginosa biofilm formation is necessary. Allium sativum is a suitable candidate because of its relative abundance. This study was carried out to determine the effect of ethanolic A. sativum extract on the expression of the P. aeruginosa biofilm gene, pelF. The presence of the pelF gene in the isolates used for this study was confirmed via polymerase chain reaction (PCR) and agarose gel electrophoresis. P. aeruginosa cultures treated with 1 g/ml of the A. sativum extract had the least turbidity (6.7 absorbance value at A600). The expression profile of the pelF gene in the treated cultures was determined via PCR using cDNA synthesized from RNA isolated from the treated P. aeruginosa cultures. The amplicons from the PCR were analyzed via agarose gel electrophoresis and a concentration dependent down-regulation of the pelF gene was observed. Further quantification of the pelF gene’s expression was performed via real-time PCR using rpoB as the reference gene. A 4-fold down-regulation of the gene was observed at 0.5 and 1 g/ml concentrations, respectively. This study suggests that the suppression of the pelF gene of P. aeruginosa by A. sativum extracts plays a role in the inhibition of P. aeruginosa biofilm formation. This is the first study to elucidate the effect of A. sativum on the expression of any of the pel genes. Key words: Allium sativum, biofilm, cDNA, down-regulation, gene expression, pelF, Pseudomonas aeruginosa, quantitative polymerase chain reaction (qPCR).

The emergence of antibiotic-resistant bacterial pathogens, especially Gram-negative bacteria, has driven investigations into suppressing bacterial virulence via quorum sensing (QS) inhibition strategies instead of bactericidal and bacteriostatic approaches. Here, we investigated several bee products for potential compound(s) that exhibit significant QS inhibitory (QSI) properties at the phenotypic and molecular levels in Chromobacterium violaceum ATCC 12472 as a model organism. Manuka propolis produced the strongest violacein inhibition on C. violaceum lawn agar, while bee pollen had no detectable QSI activity and honey had bactericidal activity. Fractionated manuka propolis (pooled fraction 5 or PF5) exhibited the largest violacein inhibition zone (24.5 ± 2.5 mm) at 1 mg dry weight per disc. In C. violaceum liquid cultures, at least 450 µg/ml of manuka propolis PF5 completely inhibited violacein production. Gene expression studies of the vioABCDE operon, involved in violacein biosynthesis, showed significant (≥two-fold) down-regulation of vioA, vioD and vioE in response to manuka propolis PF5. A potential QSI compound identified in manuka propolis PF5 is a hydroxycinnamic acid-derivative, isoprenyl caffeate, with a [M−H] of 247. Complete violacein inhibition in C. violaceum liquid cultures was achieved with at least 50 µg/ml of commercial isoprenyl caffeate. In silico docking experiments suggest that isoprenyl caffeate may act as an inhibitor of the violacein biosynthetic pathway by acting as a competitor for the FAD-binding pockets of VioD and VioA. Further studies on these compounds are warranted toward the development of anti-pathogenic drugs as adjuvants to conventional antibiotic treatments, especially in antibiotic-resistant bacterial infections.