Infectious Bronchitis Vaccine Research Articles

Cytokine and acute-phase proteins response following vaccination against infectious bronchitis in broilers.

Infectious bronchitis (IB) is an important disease of poultry, and vaccination is the best method of preventing IB in the poultry industry worldwide. This study was designed to evaluate cytokine and acute-phase protein (APP) responses and their correlations with antibody titres following vaccination regimes against IB in the broiler. Broilers were vaccinated with H120 and 1/96 vaccine strains, and MIX (H120+1/96) vaccine strains on Days 0 and 14. Heterophils/lymphocyte (H/L) ratio, APPs including chicken serum amyloid A (SAA), chicken pentraxin 3 (chPTX3), chicken interleukin 1β (IL-1β), chicken interleukin 6 (IL-6) levels and antibody titres were measured. An increase in the H/L ratio, SAA, chPTX3, IL-1β and IL-6 levels in vaccinated groups was observed 1 day after the first (highest rates) and second (lower levels) vaccination up to 3 days in three different patterns and then started to decrease. The results showed an immediate, short-lived response and moderate increases in all criteria. Changing patterns of APPs were different but in similar pattern after the first and second immunization in vaccinated groups. A positive correlation between all criteria values on Days 1 and 15 with antibody titres on Day 28 may indicate agonistic cross-regulation. Different types of IB vaccines could induce different patterns of APPs responses, which can be used to evaluate immune response outcomes in vaccine design, development and administration. The IL-6 with the highest increase can be a sensitive parameter and chPTX3 with the high increase could be an important criterion.

Safety evaluation of recombinant Newcastle disease virus expressing IBV multi-epitope chimeric live vaccine.

Newcastle Disease (ND) and Infectious Bronchitis (IB) are two significant diseases that pose threats to the poultry industry, caused by Newcastle disease virus (NDV) and Infectious bronchitis virus (IBV), respectively. Currently, the control and prevention of these diseases primarily rely on vaccination. However, commercial ND and IB vaccines face challenges such as poor cross-protection of inactivated IBV strains and interference from live vaccines when used together, leading to immunization failures. Previously, we reported the successful rescue of a recombinant NDV expressing multiple epitopes of IBV, named rNDV-IBV-T/B, which showed promising immunoprotective efficacy against both NDV and IBV. This study focuses on the biosafety of the genetically modified recombinant vaccine candidate rNDV-IBV-T/B. Immunization was performed on day-old chicks, ducklings, goslings, and ICR mice. Observations were recorded on clinical symptoms, body weight changes, and post-mortem examination of organs, as well as histopathological preparations of tissue samples. The results indicated that the rNDV-IBV-T/B vaccine candidate had no adverse effects on the growth of targeted animals (chickens) and non-target species (ducks, geese) as well as in mammals (mice). Additionally, histopathological slides confirmed that the vaccine is safe for all tested species. Further studies evaluated the potential of rNDV-IBV-T/B to spread horizontally and vertically post-immunization, and its environmental safety. The findings revealed that the vaccine candidate lacks the capability for both horizontal and vertical transmission and does not survive in the environment. In conclusion, the rNDV-IBV-T/B strain is safe and holds potential as a new chimeric live vaccine for ND and IB.

Control of Field Infectious Bronchitis Virus Genotype GI-23 (Variant 2) Using Combined Heterologous Vaccine Genotype Strains GI-13 (1/96) and GI-1 (H120)

Infectious bronchitis (IB) is a disease with significant economic impacts both on the costs of control strategies and on productive losses. Various vaccination protocols are applied, depending on homologous or heterologous protection against IB and finding the optimal balance between costs and benefits as a choice by a responsible veterinarian. The current case study aimed to demonstrate the efficacy of a heterologous vaccine combination against field IBV GI-23 (Variant 2) infection when vaccination quality was properly monitored. Two groups, each consisting of six flocks, were examined before and after improving the quality of IB vaccine application in the hatchery. These groups were vaccinated with H-120 and 1/96 vaccine strains for heterologous protection. The study involved field visits, necropsies, serology via ELISA, and oropharyngeal sampling for RT-PCR follow-up activities. Moreover, performance parameters including average body weight, feed conversion ratio, and 7 days plus total mortality were analyzed at the end of the production cycle at 40-45 days of age. Results indicated that the group with enhanced vaccination quality in the hatchery exhibited a significant decrease in IBV titers and an absence of IBV GI-23 field infection. Additionally, there was an improvement in performance data in terms of average body weight, FCR and total mortality. Hatchery vaccination proved to be more controllable and practical compared to traditional on-farm vaccination, ensuring better control of the vaccination process and massive coverage of the farm population. Keywords: Heterologous protection, Infectious bronchitis, Vaccine strain 1/96, Variant 2

Synergistic effects of oral inoculation with a recombinant Lactobacillus plantarum NC8 strain co-expressing interleukin-2 and interleukin-17B on the efficacy of the infectious bronchitis vaccine in chickens

Mucosal vaccination strategies are easier to implement than others in large-scale poultry farming. However, the adjuvants that are approved for veterinary use, which are predominantly aluminum- and oil-emulsion-based adjuvants, are not suitable for mucosal vaccination and carry a risk of adverse reactions. In this study, we engineered a novel Lactobacillus plantarum NC8 strain that co-expresses chicken interleukin-2 (IL-2) and IL-17B, which we designated NC8-ChIL2-17B, and evaluated its potential as an oral immunoadjuvant. The immunomodulatory properties of NC8-ChIL2-17B were evidenced by its ability to activate macrophages and inhibit the proliferation of infectious bronchitis virus (IBV) in vitro. We then confirmed its immunoadjuvant activity in vivo by orally administering NC8-ChIL2-17B along with a commercial IBV vaccine to chicks. The results indicated that NC8-ChIL2-17B enhanced the immune response elicited by the IBV vaccine and increased the levels of IBV-specific IgG and sIgA antibodies produced in response to IBV infection. Additionally, administration of NC8-ChIL2-17B promoted weight gain and beneficially modulated the gut microbiota, resulting in improved chicken performance. These findings suggest that oral administration of NC8-ChIL2-17B is a promising strategy to enhance the immune efficacy of the IBV vaccine in chickens, offering an efficacious alternative adjuvant.

Heterologous maternal antibodies derived from infectious bronchitis vaccines prevent the development of lesions associated with false layer syndrome

Infectious bronchitis virus (IBV) strains of the Delmarva (DMV)/1639 genotype have been causing false layer syndrome (FLS) in the Eastern Canadian layer operations since the end of 2015. FLS is characterized by the development of cystic oviducts in layer pullets infected at an early age. Currently, there are no homologous vaccines for the control of this IBV genotype. Our previous research showed that a heterologous vaccination regimen incorporating Massachusetts (Mass) and Connecticut (Conn) IBV types protects layers against DMV/1639 genotype IBV. The aim of this study was to investigate the role of maternal antibodies conferred by breeders received the same vaccination regimen in the protection against the development of DMV/1639-induced FLS in pullets. Maternal antibody-positive (MA+) and maternal antibody-negative (MA−) female progeny chicks were challenged at 1 day of age and kept under observation for 16 weeks. Oviductal cystic formations were observed in 3 of 14 birds (21.4 %) in the MA− pullets, while the lesions were notably absent in the MA+ pullets. Milder histopathological lesions were observed in the examined tissues of the MA+ pullets. However, the maternal derived immunity failed to demonstrate protection against the damage to the tracheal ciliary activity, viral shedding, and viral tissue distribution. Overall, this study underscores the limitations of maternal derived immunity in preventing certain aspects of viral pathogenesis, emphasizing the need for comprehensive strategies to address different aspects of IBV infection.

Protection Against Infectious Bronchitis Virus Vaccine Recombinants and Chicken-Selected Vaccine Subpopulations.

Outbreaks of infectious bronchitis (IB) continue to occur from novel variants of IB virus (IBV) emerging from selection of vaccine subpopulations and/or naturally occurring recombination events. S1 sequencing of Arkansas (Ark) -type viruses obtained from clinical cases in Alabama broilers and backyard chickens shows both Ark Delmarva Poultry Industry (ArkDPI) vaccine subpopulations as well as Ark vaccine viruses showing recombination with other IB vaccine viruses. IB Ark-type isolates AL5, most similar to an ArkDPI vaccine subpopulation selected in chickens, AL4, showing a cluster of three nonsynonymous changes from ArkDPI subpopulations selected in chickens, and AL9, showing recombination with Massachusetts (Mass) -type IBV, were examined for pathogenicity and ability to break through immunity elicited by vaccination with a commercial ArkDPI vaccine. Analysis of predicted S1 protein structures indicated the changes were in regions previously shown to comprise neutralizing epitopes. Thus, they were expected to contribute to immune escape and possibly virulence. Based on clinical signs, viral load, and histopathology, all three isolates caused disease in naïve chickens, although AL9 and AL5 viral loads in trachea were statistically significantly higher (30- and 40-fold) than AL4. S1 gene sequencing confirmed the stability of the relevant changes in the inoculated viruses in the chickens, although virus in some individual chickens exhibited additional S1 changes. A single amino acid deletion in the S1 NTD was identified in some individual chickens. The location of this deletion in the predicted structure of S1 suggested the possibility that it was a compensatory change for the reduced ability of AL4 to replicate in the trachea of naïve chickens. Chickens vaccinated with a commercial ArkDPI vaccine at day of hatch and challenged at 21 days of age showed that vaccination provided incomplete protection against challenge with these viruses. Moreover, based on viral RNA copy numbers in trachea, differences were detected in the ability of the vaccine to protect against these IBV isolates, with the vaccine protecting the most poorly against AL4. These results provide additional evidence supporting that IBV attenuated vaccines, especially ArkDPI vaccines, contribute to perpetuating the problem of IB in commercial chickens.

The effect of bromhexine on mucosal immune response against avian coronavirus infectious bronchitis vaccine in chickens

Avian coronavirus infectious bronchitis (IB) is one of the most important and contagious disease in chickens, all over the world. Using of chemical compounds that improve the mucosal immune response to IB vaccine can increase resistance against the virus. To examine the effect of Bromhexine on the mucosal immune response against IB vaccine, 360 one-day broiler chicks were allocated to eight groups, randomly. Group one was the control group with no vaccine so that the group only used Bromhexine. Groups 2, 3, and 4 received IB vaccine for once, twice, and three times at the age of 5, 15, and 25 days, respectively. These groups received Bromhexine from 48 hrs before the vaccination to 24 hrs after receiving the vaccine in drinking water. Group five was the negative control group and did not receive Bromhexine and IB vaccine. Sampling in group five was at the age of 15 days. Groups six, seven, and eight were the main treatment control groups and received IB vaccine at the age of 5, 15, and 25 days without Bromhexine. The chickens were slaughtered 10 days after the vaccination and nose and trachea samples were collected and the mucus surface of respiratory was rinsed. Afterwards, specific immunoglobin A (IgA) level against IB vaccine in the respiratory mucus was measured through ELISA using chicken IgA specific antiglobulin. The results showed that the use of Bromhexine on the first vaccination had no effect on mucosal immune response. However, with the second and third vaccinations, antibody titter to IB vaccine was higher than chickens received vaccine without Bromhexin. It appears that using Bromhexine in booster IB vaccination can improve specific mucosal immune response.

Immunogenicity and protective efficacy of an inactivated infectious bronchitis virus vaccine candidate from a local isolate of Bangladesh

Objective: Infectious bronchitis (IB), a highly infectious acute viral disease, is a major burden to the chicken industry worldwide. The research aimed to develop an inactivated IB vaccine using local isolates and assess its immunogenicity compared to other commercial live IB vaccines. Materials and Methods: An inactivated vaccine using a candidate IB virus (PP067159.1: Alim_IB_1001) of the QX genotype was developed according to WOAH guidelines. Chickens were vaccinated with three doses (0.25, 0.5, and 1.0 ml) at 7 days old, with a booster at 37 days old via subcutaneous (SC) and intramuscular (IM) routes. Blood samples were collected on days 7, 37, and 67 to measure immune response by indirect ELISA. On day 67, chickens were challenged with a virulent IBV strain to assess vaccine protection. The experimental IB vaccine’s immunogenicity, protective efficacy, and antibody duration were compared to a live IB vaccine (Live CEVAC® IBird) using three vaccination schedules: killed-followed-killed, live-followed-killed, and live-followed-live. Results: Chickens vaccinated with SC with 1.0 ml showed higher antibody titers compared to other SC and IM routes of vaccination. SC vaccination with 0.5 and 1 ml provided the highest protection (93%). The killed-followed-killed vaccination method produced a more consistent and protective level of antibody titers in chickens compared to the other vaccination schedules. The experimental inactivated IB vaccine led to a higher survival rate (93%) compared to live-followed-killed (87%) and live-followed-live (73%), with statistical significance (p < 0.01). All three chicken groups maintained protective antibody titers (>396) at 307 days, but titers declined faster in the live-followed-live and live-followed-killed groups compared to the killed-followed-killed group. Conclusion: The study found that the experimental inactivated IB vaccination can protect com¬mercial-layer chickens from natural IB outbreaks of the QX genotype.

Comparative histopathology of three Serotypes of live infectious bronchitis vaccine (IB88 – 4/91 – H120) in broiler chickens

Infectious bronchitis in birds, caused by a coronavirus, is a highly contagious viral disease that causes economic losses in the poultry industry worldwide. It affects the respiratory, urinary, and genital tracts, and control and prevention are focused on vaccination and biosecurity measures. This study compares histopathological lesions caused by IB88, H120, and IB4-91 vaccines in broiler chickens aged 1 to 5 days. One hundred Ross 308 chickens were divided into four groups: group 1 received the IB4-91 vaccine, group 2 was administered the H120 vaccine, group 3 received the IB88 vaccine, and group 4 served as the control group. Over a period of five days, starting from the second day, five chickens from each group were randomly selected and euthanized. Histopathological samples were collected from the trachea, lungs, and kidneys, processed into slides, and examined under an optical microscope for comparative analysis. When comparing the control and vaccinated groups, there were significant differences regarding histopathological indicators. These included hyperemia and infiltration of inflammatory cells in the kidney, lung hyperemia, infiltration of inflammatory cells, necrosis of respiratory epithelium, and hyperplasia of tracheal mucous cells. Differences were noted between the IB4-91 and H120 groups regarding inflammatory cell infiltration, respiratory epithelium necrosis, tracheal mucous cell hyperplasia, and renal hyperemia. Similarly, variations were observed between the IB88 and H120 groups regarding respiratory epithelium necrosis and tracheal inflammatory cell infiltration. Furthermore, differences were identified in tracheal mucosal hyperplasia and renal hyperemia between the IB4-91 and IB88 groups. These findings highlight distinct histopathological responses induced by different vaccines in broiler chickens and emphasize the importance of vaccine selection in poultry health management.

Response of broiler breeder pullets when fed hydrolyzed whole yeast from placement to 22 wk of age

The study examined the effects of feeding broiler breeder pullets hydrolyzed whole yeast (HY) from hatch to 22 wk of age (WOA). A total of 524-day-old Ross 708 pullets were placed in floor pens (∼24 birds/pen) for the starter (0-4 WOA) and grower (5-18 WOA) phases, then transferred to the egg production facility and redistributed to ∼20 birds/pen for the prelay phase (19-22 WOA). Two diets were allocated to pens (0-18 WOA; n = 11) and (19-22 WOA; n-12). The diets were a control corn and soybean meal diet formulated to meet specifications and control plus 0.05% HY (HY). Birds had ad libitum access to feed in the first week and daily feed allocation based on pen BW from 2 WOA. Birds had free access to water throughout the trial. Body weight (BW) and uniformity (BW CV) were monitored. Boosters for infectious bronchitis and New Castle disease vaccines were administered at 18 WOA, and samples of pullets bled for antibody titer 5-day later. One pullet/pen was randomly selected, weighed, bled for plasma biochemistry, and necropsied for organ weights, ceca digesta for short-chain fatty acids (SCFA), and leg bones morphometry. In the starter and grower phases, birds fed HY were lighter and gained less (P < 0.05) than control birds. However, there were no diet effects (P > 0.05) on growth, the BW prelay phase, or BW uniformity throughout the trial. There were no (P > 0.05) diet effects on breast, gastrointestinal, liver and bursa weights, serum antibody titers, plasma biochemistry, SCFA and bone attributes. However, pullets fed HY had heavier (P = 0.047) spleen and tended to have lower (P = 0.080) plasma concentrations of aspartate aminotransferase (AST) relative to control pullets. In conclusion, the parameters assessed showed no negative consequences of feeding HY to broiler breeder pullets. However, effects on the spleen and plasma AST may indicate modest modulation of immunity and metabolism. The impact of the provision of HY during broiler breeder pullet phase on reproductive performance and chick quality should be investigated.

Adjuvant effects of novel water/oil emulsion formulations on immune responses against infectious bronchitis (IB) vaccine in mice

Vaccines have long made use of adjuvants to boost the immune response of the body and reduce the amount of vaccine needed as well as the expense of producing the vaccine. Many vaccine adjuvants are in development, but their application in veterinary vaccinations is restricted due to their lack of efficacy or undesirable side effects. For this reason, it is essential to develop novel adjuvants. To address the issue that the currently available infectious bronchitis (IB) vaccine often fails to produce sufficient immune responses, Coral Biotechnology tested two of their newly developed water-in-oil (W/O) type emulsion adjuvants (Coralvac RZ 528 and Coralvac RZ 506) in the IB vaccine. These adjuvants were tested in a mouse model to determine whether it worked with an inactive IBV H120 vaccine. Vaccine formulations were prepared by combining a virus concentration of 1 × 106 EID50/0.1 ml with an emulsion of the W/O type in a specific ratio. Once the formulations were ready, it was injected intramuscularly as a single dosage, and the mice were monitored for 21 days afterwards. The results showed that anti-IB antibody titer (IgG and IgG1), CD3+ CD8+ T cell responses as well as IFN- γ cytokine production, and splenocyte proliferation were all considerably higher in the IBV H120 with Coralvac RZ 528 and IBV H120 with Coralvac RZ 506 formulation groups than in the viral control group. According to our findings, the humoral and cellular immune responses of mice were significantly enhanced by these novel vaccine adjuvants. Thus, our results provide evidence that the W/O type emulsion adjuvants developed by Coral Biotechnology may be a useful adjuvant in IBV vaccines.

Efficiency of Various Poultry Vaccination Methods in Industrial Poultry Farming

Introduction. Due to the growth of poultry stocking density in the allotted area in conditions of the industrial poultry farming, the issue of ensuring the epizootic welfare through vaccine-prophylaxis proves to be relevant. Another important aspect of poultry farming is reducing production costs, which could be achieved, among other things, through implementation of the cost-efficient methods of vaccination. A manual mode of spray vaccination method, which is currently used at the poultry farms, has a disadvantage because the dose of vaccine received by different birds may be unequal. However, under modern conditions, in order to increase the labour productivity and efficiency, the efforts are made to get the poultry vaccination process automated. The vaccination frame spray machines used in the industrial poultry farming have not been studied or evaluated before in a comparative aspect. Thus, the purpose of this research is to compare two methods of spray vaccination in chickens at the operating poultry farm with regard to the biological efficiency and economic profitability.Materials and Methods. The objects of the study were the young Brown Nick crossbreed chickens (n=46 heads). Vaccination was carried out in the young poultry at the age of 42-days. During the research, the dried live Newcastle disease and avian infectious bronchitis vaccines were used. To control the quality of vaccination, the amount of antibodies was estimated in the blood serum of poultry aged 56, 70 and 95 days old by ELISA method with TICAN equipment. Two groups of poultry were studied. In group 1 the “DESVAK” hand sprayer was used (“DESVAK” KIT– 2 model, produced by Ceva Santé Animale), in group 2 the automated frame spray machine was used (“SIMBIO ITERIS” model, produced by SIMBIO).Results. As a result of studies, in group 2 the higher intensity of immunity was obtained, showing on average the following figures: 56 days – antibody titre was 29 % higher (p≤0.05); 70 days – antibody titre was 18 % higher (p≤0.005); 95 days – antibody titre was 15 % higher (p≤0.05) compared to group 1. Economic efficiency was calculated based on the indicators of labour costs and labour intensity of the vaccination process: when using a frame spray machine, the costs turned out to be 2.3 times lower (1,131.4 person-rubbles) than with the DESVAK sprayer (2,590.4 person-rubbles). Additionally, the labour intensity of the vaccination process per head decreased by 5 times. In group 1 it was 0.0015 person-hour/head, in group 2 – 0.0003 person-hour/head.Discussion and Conclusion. Based on the results of the study, it was found that the spray vaccination method by means of the frame spray machine (the automated mode) is more efficient according to both biological and economic indicators compared to the manual mode. Taking into account all of the above, the frame spray machines could be recommended to the veterinary specialists for carrying out vaccine prophylaxis at the poultry farms by the spray method.

Evaluation of protection and immunity induced by infectious bronchitis vaccines administered by oculonasal, spray or gel routes in commercial broiler chicks

Broiler chicks’ responses following combined IBV live attenuated Massachusetts and 793B strains through gel, spray or oculonasal (ON) vaccination routes were cross-compared. Subsequently, the responses following IBV M41 challenge of the unvaccinated and vaccinated groups were also assessed. Post-vaccination humoral and mucosal immune responses, alongside viral load kinetics in swabs and tissues, were determined using commercial ELISA assays, monoclonal antibody-based IgG and IgA ELISA assays and qRT-PCR respectively. After challenged with IBV-M41 strain, humoral and mucosal immune responses, ciliary protection, viral load kinetics, and immune gene mRNA transcriptions between the three vaccination methods were examined and compared. Findings showed that post-vaccinal humoral and mucosal immune responses were similar in all three vaccination methods. Post vaccinal viral load kinetics is influenced by method of administration. The viral load peaked in the ON group within the tissues and the OP/CL swabs in the first and third weeks respectively. Following M41 challenge, ciliary protection and mucosal immune responses were not influenced by vaccination methods as all three methods offered equal ciliary protection. Immune gene mRNA transcriptions varied by vaccination methods. Significant up-regulation of MDA5, TLR3, IL-6, IFN-α and IFN-β genes were recorded for ON method. For both spray and gel methods, significant up-regulation of only MDA5 and IL-6 genes were noted. The spray and gel-based vaccination methods gave equivalent levels of ciliary protection and mucosal immunity to M41 virulent challenge comparable to those provided by the ON vaccination. Analysis of viral load and patterns of immune gene transcription of the vaccinated-challenged groups revealed high similarity between turbinate and choanal cleft tissues compared to HG and trachea. With regards to immune gene mRNA transcription, for all the vaccinated-challenged groups, similar results were found except for IFN-α, IFN-β and TLR3, which were up-regulated only in ON compared to gel and spray vaccination methods.

Effect of chicken infectious bronchitis vaccine on morphogenesis and differentiation of cells in caecal tonsils

The study of the chickens’ immune system morphofunctional state allows assessing critical periods of their development and the body as a whole, as well as the effectiveness of vaccine prevention methods. The purpose of this study was to identify morphological and immunohistochemical changes in the caecal tonsils of chickens aged 8, 20, 40, 90, 110 days for vaccine prevention of infectious bronchitis. During the study, the following research methods were used: cytological, histological, immunohistochemical, morphometric, light-optical, statistical. Histological preparations of caecal tonsils of poultry aged 8, 20, 40, 90, 110 days of vaccinated and unvaccinated groups were analysed and studied. Up to 20 days of age, no lymphoid nodules were detected in the caecal tonsils of chickens, both vaccinated and non-vaccinated groups. Histological and morphometric studies were conducted, which showed that vaccination of poultry accelerates the development of lymphoid formations in the early stages of the postnatal period of ontogenesis, especially in chickens aged 20 days, which is manifested by an increase in the number and size of lymphoid nodules of caecal tonsils relative to the control group. Immunohistochemical studies have established that the placement and accumulation of T-lymphocytes with markers CD4+ , CD8+ , as well as B-lymphocytes (CD20+ ) and CD45RA+ cells in caecal tonsils, namely in lymphoid nodules and diffuse accumulation of lymphoid cells, depend on the age of chickens and multiplicity of vaccinations. It was proved that in chickens aged 8 days, the number of T-lymphocyte subpopulations with surface markers CD4+ , CD8+ prevailed over CD45RA+ and CD20+ . With the increase in the number of immunizations (after three-fold vaccination against infectious bronchitis of chickens), immunocytometric studies indicated that in vaccinated chickens aged 40 and 90 days, there was a clear increase in the number of mature B-lymphocytes by 1.58 and 1.37 times, respectively. Considering the fact that the number of CD8+ lymphocytes in vaccinated chickens aged 40 days was 1.49 times greater than the number of CD4+ cells, this led to a sharp decrease in the immunoregulatory index of the caecal tonsils, which must be factored in when carrying out preventive vaccinations

Comparing real-time RT-PCR to the conventional method for titration of live attenuated avian infectious bronchitis vaccine

Comparing real-time RT-PCR to the conventional method for titration of live attenuated avian infectious bronchitis vaccine

Effects of Dietary Supplementation of Vitamin E on Growth Performance and Immune System of Broiler Chickens

As a potent antioxidant, Vitamin E may lessen the potentially harmful consequences of such oxidative stress to protect broilers against immune-pathological damage. Broiler chicken growth and viability are enhanced by Vitamin E supplementation. The present study aimed to investigate the effects of Vitamin E dietary supplementation on broiler chickens’ growth performance and health status. A total of 48 one-day-old Ross chicks were randomly divided into two groups of control and treatment (supplementation of Vitamin E at a dose of 300 mg/kg diet) with three replicates per group. The study included an equal number of Ross breed chicks and Vitamin E dosage in two trials on two different dates (January and March, 2022). In both trials, the obtained results indicated no significant changes in weight gain in the control and treatment groups. In both trials, there were no significant differences in the spleen weight of the control and treated groups; however, from day 1 to 28 of the second trial, the bursa of Fabricius was heavier in the treated group than in the control group. Additionally, Vitamin E had no significant effects on the mitogenic responses to phytohemagglutinin (PHA) and Concanavalin A (Con A). Dosages of 20 and 10 µl for both PHA and Con A did not significantly affect the rate of pure lymphocyte proliferation in chicks fed 300 mg Vitamin E /kg feed. Cell-mediated immunity did not differ significantly between the two trials. The percentages of CD4, CD8, Bu1, and MHCII molecules in the spleen and cecal tonsil of the chicks that received Vitamin E 300 mg/kg feed did not change significantly. The antibody titers against infectious bronchitis and infectious bursal disease vaccines showed no significant differences. On day 42, there was a trend toward an increase in antibody titer in the case of the Newcastle disease vaccine. In conclusion, 300 mg/kg of Vitamin E added to the diet did not improve growth performance and immunity in broiler chicks. Keywords: Broiler chicken, Growth performance, Immune system, Vitamin E

Efficacy of Two Vaccination Strategies against Infectious Bronchitis in Laying Hens.

Vaccination remains the leading control method against infectious bronchitis (IB) in poultry despite the frequently observed IB outbreaks in vaccinated flocks. Here, two vaccination regimes were evaluated against challenge with the Massachusetts (Mass) infectious bronchitis virus (IBV) strain that was linked to egg production defects in Western Canada. One vaccination strategy included live attenuated IB vaccines only, and the other used both inactivated and live attenuated IB vaccines. The two immunization programs involved priming with a monovalent live attenuated IB vaccine (Mass serotype) at day-old, followed by intervals of bivalent live attenuated IB vaccines containing the Mass and Connecticut (Conn) serotypes given to the pullets at 2-, 5-, 9-, and 14-week-old. Inactivated IB vaccine (Mass serotype) was administrated to only one group of the vaccinated birds at 14-week-old. At the peak of lay, the hens were challenged with the Mass IBV isolate (15AB-01) via the oculo-nasal route. The efficacy of the vaccines was assessed following the challenge by observing clinical signs, egg production, egg quality parameters, seroconversion, and systemic T-cell subsets (CD4+ and CD8+ cells). Moreover, the viral genome loads in the oropharyngeal (OP) and cloacal (CL) swabs were quantified at predetermined time points. At 14 days post-infection (dpi), all the hens were euthanized, and different tissues were collected for genome load quantification and histopathological examination. Post-challenge, both vaccination regimes showed protection against clinical signs and exhibited significantly higher albumen parameters, higher anti-IBV serum antibodies, and significantly lower levels of IBV genome loads in OP swabs (at 3 and 7 dpi) and trachea and cecal tonsils compared to the mock-vaccinated challenged group. However, only the birds that received live attenuated plus inactivated IB vaccines had significantly lower IBV genome loads in CL swabs at 7 dpi, as well as decreased histopathological lesion scores and IBV genome loads in magnum compared to the mock-vaccinated challenged group, suggesting a slightly better performance for using live attenuated and inactivated IB vaccines in combination. Overall, the present findings show no significant difference in protection between the two vaccination regimes against the Mass IBV challenge in laying hens.

Evolution of avian infectious bronchitis vaccine viruses reisolated from vaccinated broilers

Genetic and phenotypic diversity among infectious bronchitis virus (IBVs) is a key element of the epidemiology of avian infectious bronchitis. Virtually, all studies have focused on the evolution of wild viruses. Live-attenuated vaccine strains deserve a special attention. Two strains of IBV, 2T/17 and 16T/17, detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR) in samples from H120 vaccinated chickens showing respiratory signs, were genetically analysed targeting the S1 gene. The total RNA was extracted by the classical Trizol method. The whole S1 gene was amplified in an end-point RT-PCR using a specific primer pair, before being sequenced. The obtained sequences were compared to those of vaccine strains and reference viruses and finally subjected to a phylogenetic analysis. The two isolates turned out to be vaccine strains as evidenced by the monophyletic cluster they formed with the H120 vaccine strain (100% bootstrap). Also, they shared with this vaccine strain 99.60% and 99.47% of nucleotides (nt) for strain 2T/17 and 16T/17 respectively. The sequence alignment revealed, for each of the two strains, one non-synonymous nt substitution outside the hypervariable regions: C56T and T39G leading to two amino acid (aa) substitutions: Alv19Val and Cys13Trp, respectively for the strain 2T/17 and 16T/17. The second hypervariable region of strain 2T/17 displayed 2 nt substitutions at positions 345 and 347, resulting in an aa substitution Lys116Thr. As for 16T/17 strain, it harboured two non-synonymous nt substitutions (T353G and T380G), leading to two aa substitutions: Val118Gly and Met127Arg. The chromatogram analysis revealed minor and major peaks at all positions where nt changes were observed. Nucleotides associated with minor peaks matched with those observed in the sequence of the H120 vaccine strain at the same positions, indicating subpopulation selection. Only the substitution T353G results in a mutation as evidenced by the absence of minor peak at this position. Viral subpopulations contained in IBV live-attenuated vaccines are susceptible to be in vivo selected and emerge as persistent pathotype with reversion to virulence. This draws attention to the need of monitoring the evolution of IBV vaccine strains.

Detection of MDA titer of ınfectious bronchitis virus and comparison of antibody titer produced by two different ınfectious bronchitis vaccine

The infectious bronchitis (IB) is divesting infectious diseases of poultry. Hence, this study determined the maternally derived antibody (MDA) titer of IBV and comparison of two IB vaccine in layer. A total of 1600 birds were equally allocated into two groups (group-A and group-B). The group-A and group-B were vaccinated by two different vaccines having the strain “B1-Strain of ND+Massachusetts B-41 Strains of IBV” and “Hitchner-B1 Strain of ND+Massachusetts H120 Strains of IBV” respectively. Blood samples were collected and antibody titer was detected by indirect ELISA test. Results showed that both groups had the protective level of MDA titer and both the vaccines significantly (p&amp;lt;0.01) increased the antibody mean titer than the MDA. Between the groups, the highest antibody mean titer (11544.43±177.51) was observed in group-B at 5 weeks age and had significant (p&amp;lt;0.01) difference with group-A (10222.11±96.96). The effect size of the antibody titer was higher in group-B (14.25; CI: 9173.82-9564.39; n=46 at 5 weeks birds) than group-A (9.54; CI: 8580.19-9131.68; n=46 at one-day-old birds) respectively. Shortly, the MDA mean titer was in protective condition and both the IB vaccinated groups had the significantly (p&amp;lt;0.05) higher antibody mean titer than the protective level of antibody titer (&amp;gt;853).

Development of SYBR green RT-qPCR assay for titrating bivalent live infectious bronchitis vaccines

Infectious bronchitis (IB) is a highly contagious viral disease of chickens caused by IB virus (IBV) that can cause substantial economic losses in the poultry industry. IBV variant infections have been continuously reported since the initial description in the 1930s. QX-like IBVs are the predominant circulating genotype globally. A homologous QX vaccine has superior protection efficacy compared with that of other available vaccines, and the combination of Massachusetts (Mass)-like and QX-like strains is being used to combat QX-like IBV infections. Inoculation of embryonated chicken eggs is the standard method for the titration of IBV, and the titer is expressed as 50% egg infectious dose (EID50). However, this method cannot effectively distinguish or quantify different genotypic strains in a mixture of different viruses, especially in the absence of neutralizing monoclonal antibodies. In this study, quantitative real-time PCR (RT-qPCR) was applied using specific primers for the QX- and Mass-like strains to quantitate IBV infection and for comparison with the conventional virus titration quantitative method. A strong positive correlation was observed between RT-qPCR cycle threshold values and the different EID50 concentrations. This method was further used to titrate bivalent IB vaccines, and the amount of individual genotype virus was determined based on specific primers. Thus, this RT-qPCR assay may be used as a highly specific, sensitive, and rapid alternative to the EID50 assay for titering IBVs.