Immunological, biochemical and pathological effects of vitamin C and Arabic gum co-administration on H9N2 avian influenza virus vaccinated and challenged laying Japanese quails.

AIM: This study evaluated the effect of co-administration of vitamin C and Arabic gum (AG) supplements on the response of vaccinated (VAC) and challenged laying Japanese quails with avian influenza virus (AIV) H9N2. MATERIALS AND METHODS: One hundred and fifty 49-day-old laying Japanese quails were divided into 5 groups (G1-G5): the G1 group was a negative control, G2 group was unvaccinated + H9N2 challenged (Ch), G3 group was unvaccinated + supplements + Ch, G4 group was VAC + Ch, and the G5 group was VAC + supplements + Ch. The supplements (vitamin C, 1 g/liter of drinking water and AG, 1% ration) were given for 5 weeks post-vaccination (PV). The birds were injected subcutaneously with an inactivated H9N2 vaccine at 49 days of age. The quails were then challenged intranasally with AIV H9N2 at the 3rd week PV. Blood, tracheal swab and tissue samples were collected at the 1st, 2nd, and 3rd weeks PV, and at different time points post-challenge (PC). RESULTS: Growth performance, egg production (%), egg and eggshell weights, HI antibody titers, clinical signs, lesions, mortality, virus shedding rates, leukogram, biochemical and immunological parameters and histopathological lesions PC showed significant differences (P < 0.05) between the vaccinated-unsupplemented (G4) group and the vaccinated-supplemented (G5) group. G5 showed the highest (P < 0.05) growth performance, egg production, HI antibody titers, and heterophil phagocytic activity and the lowest heterophil/lymphocyte (H/L) ratio, mortality, virus shedding rates, creatinine level and histopathological lesion scores in the lungs. CONCLUSION: The co-administration of vitamin C and AG for 5 weeks can improve growth performance, egg production and the immune response in vaccinated laying quails challenged with AIV H9N2.

Antimicrobial, immunological and biochemical effects of florfenicol and garlic (Allium sativum) on rabbits infected with Escherichia coli serotype O55: H7.

Florfenicol (FFC) is a synthetic broad-spectrum antibiotic and garlic has a bactericidal action against coliforms. This study was carried out to compare the antimicrobial, immunological and biochemical effects of florfenicol and garlic, for their ability to treat enteropathogenic Escherichia coli serotype O55: H7 infection in rabbits. Four groups (G1-G4) were included. G1 group was the negative control; G2 group was the infected with a field-isolated strain of E. coli and untreated; G3 group was the infected+treated with FFC for 5 days; and G4 group was the infected+treated with garlic tablets for 14 days. The rabbits were observed for clinical signs, growth performance and mortality rates. Garlic-infused disks had a larger clear zone of inhibition than other antibiotic disks. Garlic treatment improved growth performance, biochemical parameters, and immunological response and reduced the fecal shedding and histopathological lesions in E. coli O55: H7 infected rabbits compared to the other groups. Colonization of E. coli more rapidly declined in G3 & G4 than in G2. Hepatic and intestinal gene expressions; tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were significantly elevated in G2 compared to the other groups, and their levels were elevated more in G3 than in G4. Serum interferon-gamma (IFN-γ) and phagocytic activity were significantly elevated in G4 compared to G3. G3 revealed macrocytic hypochromic anaemia that was confirmed histopathologically by moderate haematopoiesis of the bone marrow. In conclusion, garlic powder can reduce rabbit colibacillosis, like FFC, and can enhance the immune status of rabbits.

Effect of colibacillosis on the immune response to a rabbit viral haemorrhagic disease vaccine.

Viral haemorrhagic disease (VHD) and colibacillosis are common diseases in rabbits that cause economic losses worldwide. The effect of colibacillosis on the immune response of vaccinated rabbits against rabbit haemorrhagic disease virus (RHDV) was studied. Four groups (G1-G4) were included. G1 was the negative control group; G2 was the RHDV vaccine group; G3 was the E. coli-infected group; and G4 was the E. coli-infected + RHDV vaccine group. The E. coli infection and RHDV vaccination were simultaneously performed, with another previous infection, 3 days before vaccination. At 28 days post-vaccination (PV), the rabbits (G2-G4) were challenged intramuscularly with 0.5 ml of RHDV at a dose of 103 50% median lethal dose (LD50)/rabbit. The rabbits were observed for clinical signs, body weight gain and mortality rates. Tissue, blood, serum, and faecal samples and rectal swabs were collected at 3, 5, 7, 14, 21 and 28 days PV. Significant clinical signs and mortality and a decrease in BW were observed in the infected + RHDV vaccine group. On the 3rd day post-infection (PI), compared with all the other groups, the vaccinated group (G2) had significantly upregulated hepatic tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels; however, the infected + RHDV vaccine group had significantly higher intestinal levels of TNF-α and IL-6 than the other groups. Furthermore, E. coli infection in vaccinated rabbits led to immunosuppression, as shown by significant decreases (P < 0.05) in heterophil phagocytic activity, the CD4+/CD8+ ratio, and HI antibody responses to RHDV and a significant increase in the heterophil to lymphocyte (H/L) ratio. In conclusion, colibacillosis leads to immunosuppression involving a shift in the equilibrium of cytokines and reduced weight gain and mortality in vaccinated rabbits and could be a contributing factor in RHDV vaccination failure in rabbit farming.

Comparative immune response and pathogenicity of the H9N2 avian influenza virus after administration of Immulant®, based on Echinacea and Nigella sativa, in stressed chickens.

Avian influenza vaccines are commonly used in the poultry industry, and some medicinal plants can increase the efficacy of such vaccines. The objective of this study was to evaluate the effect of Immulant® (IMU) (a commercial product based on Echinacea and Nigella sativa) on stress induced by dexamethasone (DEX) in chickens vaccinated (VAC) against the H9N2 avian influenza virus (AIV-H9N2). Seven experimental groups were included: the negative control, VAC, DEX, VAC + DEX, VAC + DEX + IMU, VAC + IMU and IMU groups. The vaccinated chickens (at 10 days of age) were injected daily with DEX for three days pre-vaccination and for three days pre-challenge and orally administered 1% IMU for 6 weeks post-vaccination (PV). The chickens were then challenged intranasally with AIV-H9N2 at 28 days PV. Serum, blood, tracheal and cloacal swabs and tissue samples were collected in the 1st and 4th weeks PV and at different time points post-challenge. The results showed significant changes (P ≤ 0.05) in oxidative stress and antioxidant biomarkers (malondialdehyde, nitric oxide and reduced glutathione), haematological and immunological parameters, final live weights, relative organ weights and histopathological lesions between the VAC+DEX group and the VAC group. Moreover, IMU significantly increased protection rates post-challenge, HI antibody titers and heterophil phagocytic activity and decreased DEX-induced stress and virus shedding titers. In conclusion, oral administration of 1% IMU for six weeks can enhance the immune response after AI-H9N2 vaccination and reduce the pathogenicity of infection in stressed chickens.