Emergence of drug resistance among the causative organisms for respiratory tract infections represents a critical challenge to the global health care community. Further, although vaccination can prevent disease, vaccine development is impeded by several factors. Therefore, novel approaches to treat and manage respiratory infections are urgently needed. Passive immunization represents a possible alternative to meet this need. Immunoglobulin Y antibodies (IgYs) from the yolk of chicken eggs have previously been used against bacterial and viral infections in human and animals. Their advantages include lack of reaction with mammalian Fc receptors, low production cost, and ease of extraction. Compared to mammalian IgGs, they have higher target specificity and greater binding avidity. They also possess remarkable pathogen-neutralizing activity in the respiratory tract and lungs. In this review, we provide an overview of avian IgYs and describe their potential therapeutic applications for the prevention and treatment of respiratory infections.

Gastric ulcers are a major problem worldwide with no effective treatment. The objective of this study was to evaluate the use of manuka honey in the treatment of acetic acid‐induced chronic gastric ulcers in rats. Different groups of rats were treated with three different concentrations of honey. Stomachs were checked macroscopically for ulcerative lesions in the glandular mucosa and microscopically for histopathological alterations. Treatment with manuka honey significantly reduced the ulcer index and maintained the glycoprotein content. It also reduced the mucosal myeloperoxidase activity, lipid peroxidation (MDA), and the inflammatory cytokines (TNF‐α, IL‐1β, and IL‐6) as compared to untreated control group. In addition, honey‐treated groups showed significant increase in enzymatic (GPx and SOD) and nonenzymatic (GSH) antioxidants besides levels of the anti‐inflammatory cytokine IL‐10. Flow cytometry studies showed that treatment of animals with manuka honey has normalized cell cycle distribution and significantly lowered apoptosis in gastric mucosa. In conclusion, the results indicated that manuka honey is effective in the treatment of chronic ulcer and preservation of mucosal glycoproteins. Its effects are due to its antioxidant and anti‐inflammatory properties that resulted in a significant reduction of the gastric mucosal MDA, TNF‐α, IL‐1β, and IL‐6 and caused an elevation in IL‐10 levels.

Antibiotic resistant bacteria are a growing threat to global health security. Whilst the emergence of antimicrobial resistance (AMR) is a natural phenomenon, it is also driven by antibiotic exposure in health care, agriculture, and the environment. Antibiotic pressure and inappropriate use of antibiotics are important factors which drive resistance. Apart from their use to treat bacterial infections in humans, antibiotics also play an important role in animal husbandry. With limited antibiotic options, alternate strategies are required to overcome AMR. Passive immunization through oral, nasal and topical administration of egg yolk-derived IgY antibodies from immunized chickens were recently shown to be effective for treating bacterial infections in animals and humans. Immunization of chickens with specific antigens offers the possibility of creating specific antibodies targeting a wide range of antibiotic-resistant bacteria. In this review, we describe the growing global problem of antimicrobial resistance and highlight the promising potential of the use of egg yolk IgY antibodies for the treatment of bacterial infections, particularly those listed in the World Health Organization priority list.

Bee products have been used since ancient times to treat many diseases, including respiratory ailments. The present study aimed to examine the modulatory effect of honey, royal jelly, and propolis extract on peripheral blood leukocytes and lung inflammation in a mouse conalbumin-induced asthma model. The mice in group I were not sensitised or treated; they were kept as controls. The mice in group II were sensitised and challenged with conalbumin. Twenty-four hours after the first challenge with antigen, the mice in group III received 0.5 mg/kg of dexamethasone intraperitoneally per day for 18 consecutive days and kept as positive controls. The mice in groups IV, V, and VI received 650, 1000, and 30 mg/kg of honey, royal jelly, and propolis (aqueous and ethanolic extract), respectively, once per day for 18 consecutive days. Blood was collected from all of the mice for white blood cell differentiation, and the lungs were removed for histopathological studies. The groups treated with propolis extract exhibited considerable ameliorative effects against asthma, which might be explained by the flavonoids and phenolics found in propolis, which might have antioxidative effects. Otherwise, the sensitised and honey- or royal jelly-treated groups exhibited an increased incidence of asthma cascade events due to increased inflammatory cells. These results might be due to the immunostimulatory and vasodilatory effects of royal jelly and honey, which are antagonistic to bronchial asthma cases. Histopathological examination revealed that the sensitised treated propolis extract groups had significant decreases in inflammatory scores compared with other treatments and the sensitised untreated group. These results confirmed the previous data of peripheral blood cells.

Safe, passive immunization methods are required against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and its variants. Immunization of chickens with antigen is known to induce specific IgY antibodies concentrated in the egg yolk and has a good safety profile, high yield of IgY per egg, can be topically applied, not requiring parenteral delivery. Our data provide the first evidence of the prophylactic efficacy of Immunoglobulin Y antibodies against SARS-CoV-2 in mice. Lohmann hens were injected with recombinant SARS-CoV-2 RBD protein; IgY-Abs were extracted from the eggs and characterized using SDS-PAGE. Antiviral activity was evaluated using plaque reduction neutralization tests. In additional experiments, IgY-RBD efficacy was examined in mice sensitized to SARS-CoV-2 infection by transduction with Ad5-hACE2 (mild disease) or by using mouse-adapted virus (severe disease). In both cases, prophylactic intranasal administration of IgY-Abs reduced SARS-CoV-2 replication, and reduced morbidity, inflammatory cell infiltration, hemorrhage, and edema in the lungs and increased survival compared to control groups that received non-specific IgY-Abs. These results indicate that further evaluation of IgY-RBD antibodies in humans is warranted.

Identified in 2012, the Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe and often fatal acute respiratory illness in humans. No approved prophylactic or therapeutic interventions are currently available. In this study, we developed chicken egg yolk antibodies (IgY Abs) specific to the MERS-CoV spike (S) protein and evaluated their neutralizing efficiency against MERS-CoV infection. S-specific IgY Abs were produced by injecting chickens with the purified recombinant S protein of MERS-CoV at a high titer (4.4 mg/mL per egg yolk) at week 7 post immunization. Western blotting and immune-dot blot assays demonstrated specific binding to the MERS-CoV S protein. In vitro neutralization of the generated IgY Abs against MERS-CoV was evaluated and showed a 50% neutralizing concentration of 51.42 μg/mL. In vivo testing using a human-transgenic mouse model showed a reduction of viral antigen positive cells in treated mice, compared to the adjuvant-only controls. Moreover, the lung cells of the treated mice showed significantly reduced inflammation, compared to the controls. Our results show efficient neutralization of MERS-CoV infection both in vitro and in vivo using S-specific IgY Abs. Clinical trials are needed to evaluate the efficiency of the IgY Abs in camels and humans.