Differential immunomodulatory effect of vitamin D (1,25 (OH)2 D3) on the innate immune response in different types of cells infected in vitro with infectious bursal disease virus

Phytochemicals: a promising approach to control infectious bursal disease

Infectious bursal disease (IBD) is one of the dangerous diseases of poultry that affects the bursa of Fabricius, which is an important organ of the bird's immune system. IBD virus is resistant to many drugs, making its control difficult. Vaccination of IBD is in practice for a long time worldwide to control IBD, but secondary issues like vaccine failure and lower efficacy lead to their reduced use in the field. Multiple medicines are currently used, but the phytochemicals have emerged as promising agents for controlling IBD. The drugs to be developed should possess direct antiviral properties by targeting viral entry mechanisms, enhancing the host immune response, and inhibiting viral protein synthesis. Phytochemicals have potential to contribute to food security by minimizing the possibility of disease outbreaks and ensuring that consumers worldwide obtain healthy poultry products. It has been now claimed that direct and indirect activities of phytochemicals can be effective in the control of IBDV. Although available evidence suggest that the phytochemicals can contribute in controlling occurrence IBDV, there is a definite need of focused studies to gain more insight and develop rational strategies for their practical use. This review highlights the disease caused by IBDV, inhibition of viral replication, boosting the immune system, disruption of viral membrane, and important phytochemicals showing antiviral activities against IBDV.

Molecular cloning, expression analysis and functional characterization of chicken cytochrome P450 27A1: A novel mitochondrial vitamin D3 25-hydroxylase

Vitamin D₃ is hydroxylated by cytochrome P450 (CYP) before exerting biological effects. The chicken CYP involved in vitamin D₃ 25-hydroxylation has yet to be cloned, and little is known about its functional characteristics, tissue distribution, and cellular expression. We identified a novel, full-length CYP27A1 gene cloned from chicken hepatocyte cDNA that encodes a putative protein of 518 amino acids. Swiss modeling revealed that chicken CYP27A1 has a classic open-fold form. Multisequence homology alignment determined that CYP27A1 contains conserved motifs for substrate recognition and binding. Quantitative real-time PCR analysis in 2-mo-old Partridge Shank broilers demonstrated that CYP27A1 mRNA levels were highest in the liver, followed by the thigh muscles, the breast muscles, and kidneys. The transcripts of CYP27A1 in breast muscles were significantly higher in males than in females. A subcellular localization analysis demonstrated that CYP27A1 was mainly expressed in the mitochondria. In vitro enzyme assays suggested that recombinant CYP27A1 hydroxylates vitamin D₃ at the C-25 position to form 25-hydroxyvitamin D₃ (25(OH)D₃). The K_m and V_max values for CYP27A1-dependent vitamin D₃ 25-hydroxylation were estimated to be 4.929 μM and 0.389 mol min^-1 mg^-1 protein, respectively. In summary, these results suggest that CYP27A1 encodes a mitochondrial CYP that plays an important physiologic role in the 25-hydroxylation of vitamin D₃ in chickens, providing novel insights into vitamin D₃ metabolism in this species.

Effects of the Vitamin D3 on Alleviating the Oxidative Stress Induced by Diquat in Wenchang Chickens

Vitamin D₃ (VD₃) is an indispensable micronutrient in livestock and poultry feed. Its function in antioxidant stress has been reported. We investigate whether the addition of different concentrations of VD₃ to the diet affects the production performance, slaughter performance, meat quality, organ index, and gut injury on the diquat (DQ)-induced model of oxidative stress in Wenchang chickens. Four hundred and eighty one-day-old chickens were randomly divided into six groups: control (basal diet), 4000 VD (basal diet + VD₃ 4000 IU per kg feed intake), 1000 VD+DI (DQ, basal diet + VD₃ 1000 IU per kg feed intake), 2000 VD+DI (DQ, basal diet + VD₃ 2000 IU per kg feed intake), and 4000 VD+DI (DQ, basal diet + VD₃ 4000 IU per kg feed intake). The results showed that the addition of VD₃ to the diet promoted DQ-induced weight loss and reduced ADFI, slaughter rate, splenic index, and pH after 1 h and 24 h in the leg muscles. VD₃ decreased the increase in content of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) among proinflammatory cytokines (p < 0.05) and increased the reduction in anti-inflammatory cytokines content of interleukin-10 (IL-10) (p < 0.05) induced by DQ. In addition, liver and kidney injury biomarkers and the intestinal permeability index in serum were disordered after treatment with DQ (p < 0.05). VD₃ perfected the increase of D-lactic acid (D-LA), diamine oxidase (DAO), total cholesterol (T-CHO), creatinine (CR), blood urea nitrogen (BUN), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) content, aspartate transaminase (AST), alanine transaminase (ALT), and lactate dehydrogenase (LDH) activity (p < 0.05); it increased the decrease of albumin (ALB) content (p < 0.05). Meanwhile, VD₃ regulated the intestinal morphology and intestinal barrier. Moreover, DQ induced a decrease in total antioxidant capacity and antioxidant enzyme activity in the serum, liver, and jejunum (p < 0.05), and an increase in malonaldehyde (MDA) content (p < 0.05). However, the addition of different levels of VD₃ could alleviate the above phenomenon of oxidative stress in Wenchang chickens to different degrees. Thus, this research suggested that the addition of VD₃ can relieve the DQ-induced oxidative stress of Wenchang chickens, and the level of VD₃ acquisition is positively correlated with the remission effect.

Rapidly Increasing Serum 25(OH)D Boosts the Immune System, against Infections-Sepsis and COVID-19

Vitamin D deficiency is a global public health problem, a pandemic that commonly affects the elderly and those with comorbidities such as obesity, diabetes, hypertension, respiratory disorders, recurrent infections, immune deficiency, and malignancies, as well as ethnic minorities living in temperate countries. The same groups were worst affected by COVID-19. Since vitamin D deficiency weakens the immune system, it increases the risk of infections, complications, and deaths, such as from sepsis and COVID-19. Deficiency can be remedied cost-effectively through targeted food fortification, supplementation, and/or daily safe sun exposure. Its endocrine functions are limited to mineral metabolism, musculoskeletal systems, specific cell membrane interactions, and parathyroid gland functions. Except for the rapid, endocrine, and cell membrane-based non-genomic functions, all other biological and physiological activities of vitamin D depend on the adequate intracellular synthesis of 1,25(OH)2D (calcitriol) in peripheral target cells via the genome. Calcitriol mediates autocrine (intracrine) and paracrine signalling in immune cells, which provides broader, protective immune functions crucial to overcoming infections. The synthesis of 1,25(OH)2D (calcitriol) in peripheral target cells is dependent on diffusion and endocytosis of D3 and 25(OH)D from the circulation into them, which requires maintenance of serum 25(OH)D concentration above 50 ng/mL. Therefore, in acute infections such as sepsis and respiratory infections like COVID-19, it is necessary to rapidly provide its precursors, D3 and 25(OH)D, through the circulation to generate adequate intracellular calcitriol. Immune defence is one of the crucial non-hormonal functions of vitamin D. A single oral (bolus) dose or divided upfront loading doses between 100,000 and 500,000 IU, using 50,000 IU vitamin D3 increase the serum 25(OH)D concentrations to a therapeutic level of above 50 ng/mL that lasts between two to three months. This takes three to five days to raise serum 25(OH)D. In contrast, a single oral dose of calcifediol (0.014 mg/kg body weight) can generate the needed 25(OH)D concentration within four hours. Considering both D3 and 25(OH)D enter immune cells for generating calcitriol, using the combination of D3 (medium-term) and calcifediol (immediate) is cost-effective and leads to the best clinical outcome. To maximise protection against infections, particularly to reduce COVID-19-associated complications and deaths, healthcare workers should advise patients on safe sun exposure, adequate vitamin D supplementation and balanced diets containing zinc, magnesium, and other micronutrients to support the immune system. Meanwhile, governments, the World Health Organisation, the Centers for Disease Control, and governments should consider similar recommendations to physicians and the public, change the outdated vitamin D and other micronutrient recommendations directed to their population, and organise targetted food fortification programs for the vulnerable groups. This article discusses a rational approach to maintaining a sustained serum 25(OH)D concentration above 50 ng/mL, necessary to attain a robust immune system for overcoming infections. Such would cost-effectively improve the population’s health and reduce healthcare costs. It also describes three cost-effective, straightforward protocols for achieving and sustaining therapeutic serum 25(OH)D concentrations above 50 ng/mL (>125 nmol/L) to keep the population healthy, reduce absenteeism, improve productivity, and lower healthcare costs.

The Immunomodulatory Properties of Vitamin D

Since its discovery, vitamin D was shown to have both immunostimulatory and immunomodulatory effects on the immune system. A growing body of evidence so far linked vitamin D deficiency with the development and severity of several systemic and organ specific autoimmune/inflammatory diseases, such as systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, and multiple sclerosis. In the present report, the multiple and diverse effects of vitamin D on the immune system are reviewed.

Folic acid enhances proinflammatory and antiviral molecular pathways in chicken B-lymphocytes infected with a mild infectious bursal disease virus

1. This study evaluated the effect of folic acid (FA) supplementation on the proinflammatory and antiviral molecular pathways of B-lymphocytes infected with a modified live IBDV (ST-12) mild vaccine strain during a timed post-infection analysis.2. A chicken B-lymphocytes (DT-40) cell line was cultured in triplicate at a concentration of 5 × 10⁵ cells per well in 24-well plates; and was divided into three groups: 1: No virus, FA; 2: Virus, no FA; 3: Virus + FA at a concentration of 3.96 mM. The experiment was repeated three times.3. Cells in groups 2 and 3 were infected with a modified live IBDV (ST-12) mild vaccine strain at one multiplicity of infection (MOI: 1). After 1 hour of virus adsorption, samples were collected at 0, 3, 6, 12, 24 and 36 hours post-infection (hpi).4. The modified live IBDV (ST-12) mild vaccine strain triggered a B-lymphocyte specific immune response associated with the upregulation of genes involved in virus recognition (Igß), virus sensing (TLR-2, TLR-3, TLR-4 and MDA5), signal transduction and regulation (TRIF, MyD88 and IRF7), and the antiviral effector molecules (IFN-α, OAS, PKR, and viperin).5. FA supplementation modulated IBDV replication and regulated the proinflammatory and antiviral downstream molecular pathways.6. In conclusion, the low virulent pathotype serotype I modified live IBDV (ST-12) mild vaccine strain was able to trigger and mount an immune response in chicken B-lymphocytes without affecting B-cell viability. FA supplementation modulated B lymphocytes response and improved their innate immune proinflammatory and antiviral response molecular pathways.