Procedures for the haemagglutination and the haemagglutination inhibition tests for avian infectious bronchitis virus

Mannan oligosaccharides as a prebiotic for laying hens: effects on fertility, hatchability, productive performance, and immunity

This experiment examined how adding mannan-oligosaccharides (MOS) to the diet affected fertility, hatching rates, egg production, carcass characteristics, cost-effectiveness, and immune function in laying hens. One hundred and twenty Mandarah chickens (30 hens and 3 roosters per group) were randomly chosen between 34 and 50 wk old and divided into four groups. The first group was the control group, which was given just the basal diet. The basal diet was given to the second, third, and fourth experimental groups along with three different levels of MOS (0.1, 0.2, and 0.5 g/kg diet, respectively). Results found that hens fed MOS at various levels laid eggs at a significantly higher rate, enhanced egg number, egg mass and feed conversion ratio than the control group (P < 0.05). MOS seemed to improve carcass quality. The best results for egg quality (Haugh unit) and testosterone levels were seen with a dose of 0.5 g/kg of MOS compared to the control birds (P < 0.05). All MOS levels led to higher estradiol-17β (E2) levels and better economic efficiency (EE). MOS also improved the hens' immune systems as compared to the control group. Hens-fed MOS had significantly greater levels of antibodies against Influenza viruses (H9N2) and Infectious Bronchitis Virus (P < 0.05). Also, the spleen and thymus gland, both crucial immune system components, were slightly larger (P < 0.05). It's important to note that fertility rates, hatchability, and embryo mortality rates remained similar across all groups. So, our findings suggest that incorporating MOS into the birds' diet enhances their productivity, strengthens their immune system, improves EE, and contributes to the overall health of the hens.

Enhancing effect of oregano essential oil and Bacillus subtilis on broiler immune function, intestinal morphology and growth performance

The present study evaluated the effect of two categories of feed additives on chicken performance through immunological and intestinal histo-morphometric measurements. A total of 150 one-day-old male broiler chicks (Cobb) were randomly assigned to three groups. Group I received a non-supplemented basal diet. While groups II and III were treated with a basal diet supplemented with oregano essential oil (OEO) and Bacillus subtilis, respectively, in water for 28 days. Blood samples were taken at 6, 18 and 28 days for hematological analysis, phagocytosis, lymphocyte proliferation and measuring antibody responses. Additionally, growth performance indices were recorded weekly. The results showed that groups supplemented with OEO and B. subtilis improved growth performance expressed by a significant increase in weight gain (P < 0.05), with a significant reduction (P < 0.05) in feed conversion ratio (FCR). Hematological findings indicated a significant increase in blood parameters as well as a significant increase in phagocytic % & phagocytic index at all time points with a greater probiotic effect. On the other hand, OEO produced a significant increase in lymphocyte proliferation at 18 & 28 days. Humoral immunity revealed a significant increase in serum antibody titer phytobiotic & probiotic-fed groups at time points of 18 & 28 days with a superior phytobiotic effect. The histological examination showed a significant increase in villi length, villi width, crypt depth & V/C ratio. In conclusion, these results indicated positive effects of B. subtilis & OEO on both growth and immunity and could be considered effective alternatives to the antibiotic.

Different levels of single-strain probiotic (Bacillus subtilis) with proteolytic enzyme (serratiopeptidase) can be used as an alternative to antibiotic growth promoters in broiler

In the current study, the proteolytic enzyme (serratiopeptidase) was used to enhance the efficacy of Bacillus subtilis (B. subtilis) probiotic as a growth promotor in broiler chicken. The effects of serratiopeptidase on the efficacy of different levels of B. subtilis as a growth promotor in broiler chicks were evaluated regarding growth performance traits, villus histomorphometric characterization, and intestinal microbiota count. Day-old broiler chicks (n = 120) were allocated into 4 groups having 3 replicates/group. In the control group (C), the basal diet was kept without supplementation. In treatment groups (P100, P150, and P200), the basal diet was supplemented with 100, 150, and 200 mg probiotics, respectively besides 30 mg proteolytic enzyme in the 3 treated groups for 4 wk. The performance parameters were significantly affected by the supplementation of serratiopeptidase to the B. subtilis treatment groups. Feed intake (FI), body weight gain (WG), feed conversion ratio (FCR), and dressing percent were significantly improved in the treatment groups as compared to the control group. Significantly, the lowest feed intake was recorded for the P200 group. The highest body weight gain and dressing percentage were recorded for the P200 group. An improved FCR was recorded in the P200 group (1.7) as compared to the control group. The different levels of B. subtilis supplemented with serratiopeptidase revealed significant improvements (P<0.05) in the morphology of the intestine by showing increases in villus height and width and crypt depth of the small intestine. The microbial count revealed that E. coli and salmonella colonies were significantly reduced in the P200 group as compared to the control and other treatment groups. In conclusion, the supplementation of B. subtilis with serratiopeptidase as a growth promoter in broiler chicks significantly improved the overall performance, and intestinal health and reduced microbial load contributing to optimizing the performance of broiler chickens. The greatest improvement was observed in the P200 group fed with B. subtilis as a probiotic and serratiopeptidase enzyme (200 mg:30 mg).

Effect of citrus peeling (Citrus sinensis) on production performance, humoral immunity, nutrients, and energy utilization of broiler quails

Citrus citrus peeling has a wide range of vitamins and trace minerals that have antioxidant and antimicrobial properties. It is hypothesized that the addition of citrus peeling to broiler quail diets can improve their production performance, humoral immunity, nutrients, and energy utilization. A trial was performed to study the impact of a methanolic extract of citrus peeling (Citrus sinensis) on production performance, humoral immunity, nutrients, and energy utilization of broiler quails. A healthy day-old 300 quails were randomly assigned with 5 replicates each replicate had 15 birds and used CRD for the trial. Different dietary supplementations were presented to different groups. The control group was not supplemented with any supplementation in their feed. While, the 3 other groups were supplemented by 0.5 mL/kg, 1 mL/kg, and 1.5 mL/kg of methanolic extract of dried Citrus sinensis peel (DCSP) in the basal diet (DCSP0.5, DCSP1, and DCSP1.5 groups, respectively). All the birds were allowed ad libitum feeding and water. The feed intake and FCR were significantly higher in the control group, followed by DCSP0.5, and then DCSP1. The significantly lowest feed intake and FCR were observed in the DCSP1.5 group. The weight gain and dressing % were significantly improved with the increasing level of methanolic extract of Citrus sinensis. The significantly highest weights of thymus, spleen, and bursa were recorded in the DCSP1.5 group, followed by the DCSP1. The antibody titers against infectious bursal disease, New Castle disease, and infectious bronchitis disease were significantly higher in the DCSP1.5, DCSP1, and DCSP0.5 groups than in the control group. It was concluded from the study that supplementation of quails with methanolic extract of citrus at a dose rate of 0.5 to 1.5 mL/kg of feed can improve feed intake, weight gain, FCR, dressing percentage, relative weight of lymphoid organs, and digestibility coefficient. Supplementation of Citrus sinensis has also concluded positive impacts on antibody titers against various viral diseases. The best improvement in the evaluated parameters was observed at a dose of extract of citrus was 1.5 mL/kg of feed.

Synthesis of Gold-PVP Nanostructured Composites by Microplasma: A Test to Study Their Inhibiting Tendency of Avian Influenza Virus Activity

Gold–polymer nanostructured composites have a great potential in the biomedical and advanced materials field as an antimicrobial agent against various pathogens, especially viruses. In the present work, gold and gold-PVP colloids have been prepared by the electrochemical reduction of hydrogen tetrachlorauric acid (HAuCl4·3H2O) precursor. The atmospheric pressure microplasma technique was used as a reducing agent, while D-Fructose was used as a stabilizing agent in the synthesis process. X-ray Diffraction (XRD) confirmed the crystalline behavior of both gold nanostructured particles and gold-PVP nanocomposites. The morphology of the nanoparticles was examined by SEM. The absorption characteristic peaks at 541 nm and 542 nm in UV-Vis spectra confirmed the surface plasmon resonance in gold nanostructured particles and gold-PVP nanostructured composites, respectively. Dynamic light scattering studies with percentage intensity distribution revealed particle size distribution ranges from 8–288 nm for gold colloids and 15–297 nm for gold-PVP colloids. Gold-PVP nanostructured composites have shown an improvement in the antiviral activity against the H9N2 virus as compared to bare gold nanostructured particles.

Molecular evaluation and genetic characterisation of Newcastle disease virus's haemagglutinin-neuraminidase protein isolated from broiler chickens in Iran

Background

Newcastle disease (ND) virus (NDV) is one of the major pathogens in poultry farms that causes severe economic damages to the poultry industry, especially broiler chicken and turkey farms. Despite the endemicity of ND and its many epidemics in the country, the nature of the Iranian strain of the Newcastle virus is still largely unknown. This study aimed to characterise and evaluate NDV isolates obtained from commercial poultry farms in Iran in 2019 through haemagglutinin‐neuraminidase (HN) gene sequencing.

Method

HN gene of each NDV isolate was amplified and sequenced using specific primers followed by phylogenetic analysis of full length of HN gene open reading frame and amino acid (aa) sequence of HN.

Results

Phylogenetic analysis of the HN gene showed that the virus is very closely related to genotypes VII and III. Analysis of HN gene nucleotide sequences showed that all isolates encode proteins with a length of 571 aa.

Conclusion

Results of the present study are useful for a better understanding of molecular epidemiology of indigenous NDV strains and determining important molecular differences between fields and commonly used vaccine strains related to main immunogenic proteins.

Evaluation of the oncolytic property of recombinant Newcastle disease virus strain R2B in 4T1 and B16-F10 cells in-vitro

Recombinant Newcastle disease virus vectors have gained a lot of interest for its oncolytic virus therapy and cancer immune therapeutic properties due to its selective replication to high titers in cancer cells. The aim of this study was to find out the oncolytic effects of mesogenic recombinant NDV strain R2B-GFP on murine mammary tumor cell line 4T1 and murine melanoma cell line B16-F10. The anti-tumor effects of R2B-GFP virus were studied via expression of virus transgene GFP in cancer cells, evaluating its cytotoxicity and cell migration efficacies by MTT and wound healing assays respectively. In addition, the underlying apoptotic mechanism of R2B-GFP virus was estimated by TUNEL assay, colorimetric estimation of Caspase-3, 8 and 9 and the estimation of Bax to Bcl-2 ratio. The results showed a significant decrease in viability of both 4T1 and B16-F10 cells infected with R2B-GFP virus at 0.1 and 1 MOI. R2B-GFP virus could significantly induce apoptosis in the 4T1 and B16-F10 cells as compared to the uninfected control. Further, a flow cytometry analysis on apoptotic cells percentage and mitochondria membrane permeability test was also studied in R2B-GFP virus treated 4T1 and B16-F10 cell lines. The R2B-GFP virus caused an increase in loss of mitochondrial membrane permeability in both 4T1 and B16-F10 cells indicating the involvement of mitochondrial regulated cell death. Thus, the recombinant virus R2B-GFP virus proved to be a valid candidate for oncolytic viral therapy in 4T1 and B16-F10 cells.

The emergence, evolution and spread of infectious bronchitis virus genotype GI-23

Avian infectious bronchitis is a contagious viral disease, caused by avian infectious bronchitis virus (IBV), that leads to severe losses in the poultry industry all over the world. Since the 1950s, IBV has circulated in the Middle East and North Africa, and no tangible evidence has shown any effects of measures taken to control its spread or evolution. Furthermore, new IBV variants are continually discovered. Although several genetic studies on IBV have been conducted, many IBV strains from this region have either been misclassified or remain unclassified. The genotype 23 (GI-23) variant emerged and has prevailed in the Middle East by continuously evolving through inter- and/or intra-genotypic recombination. The GI-23 genotype is currently enzootic throughout Europe and Asia. Although many studies of protection against the circulating strains have been conducted, they have not been standardized according to regulatory requirements. In this review, we provide an overview of the evolution and genetic diversity of IBV genotypes and a genetic classification of IBV strains, with a focus on the GI-23 genotype. The high prevalence of IBV GI-23 strains necessitates the adoption of vaccination schemes using GI-23-based vaccines.

Association of LEI0258 Marker Alleles and Susceptibility to Virulent Newcastle Disease Virus Infection in Kuroiler, Sasso, and Local Tanzanian Chicken Embryos

Newcastle disease (ND) control by vaccination and an institution of biosecurity measures is less feasible in backyard chicken in developing countries. Therefore, an alternative disease control strategy like the genetic selection of less susceptible chicken genotypes is a promising option. In the present study, genetic polymorphism of LEIO258 marker and association with susceptibility to virulent Newcastle disease virus (NDV) infection in Kuroilers, Sasso, and local Tanzanian chicken embryos were investigated. Samples from high (15%) and less (15%) susceptible cohorts were genotyped by sequencing of LEI0258 marker. A total of 75 DNA sequences comprised of 29 Kuroiler, 29 local Tanzanian chickens, and 17 Sasso were analyzed. Neighbor-joining phylogenetic trees were constructed to depict the clustering of LEI0258 marker alleles and relationship with susceptibility. Alleles with frequency ≥3 were considered for association with susceptibility by the use of the inference technique. The present findings suggest that some LEI0258 marker genetic polymorphisms apart from LEI0258 marker allelic based on sizes may be linked with chicken MHC-B haplotypes that confer chickens variability in resistance or susceptibility to infections. Furthermore, these results demonstrate the presence of relationship between LEI0258 marker polymorphisms and variations in chicken susceptibility to NDV infection, which could be utilized in breeding programs designed to improve chicken disease resistance.

Evaluation of Japanese encephalitis virus E and NS1 proteins immunogenicity using a recombinant Newcastle disease virus in mice

Japanese encephalitis (JE) is the most important cause of acute encephalitis syndrome (AES). Japanese encephalitis virus (JEV), the prototype member of the JE serocomplex, belongs to the genus Flavivirus. The immunogenic proteins envelope (E) and non-structural protein 1 (NS1) of JEV are widely explored for the development of vaccines and diagnostics against JEV. However, there are underlying concerns such as the risk of reversion of live-attenuated vaccines to high virulence, the incomplete inactivation of pathogens in inactivated vaccines and partial vaccine coverage. Newcastle disease virus (NDV) is an efficient viral vaccine vector to express several human and animal immunogenic proteins. In the present study, we have developed a recombinant NDV (rNDV), individually expressing the E and NS1 proteins of JEV (rNDV-Ejev and rNDV-NS1jev). The recovered rNDV-Ejev and rNDV-NS1jev were characterized in 9-day-old SPF embryonated chicken eggs and in cell culture. The vaccination of rNDV-Ejev and rNDV-NS1jev showed effective immunity against JEV upon intranasal immunization in BALB/c mice. The rNDVs vaccination produced effective neutralization antibody titers against both NDV and JEV. The cytokine profiling of the vaccinated mice showed an effective Th1 and Th2 mediated immune response. The study also provided an insight that E, when used in combination with NS1 could reduce the efficacy of only E based immunization in mice. Our results suggested rNDV-Ejev to be a promising live viral vectored vaccine against JEV. This study implies an alternative and economical strategy for the development of a recombinant vaccine against JEV.

Comparative protective immunity provided by live vaccines of Newcastle disease virus or avian metapneumovirus when co-administered alongside classical and variant strains of infectious bronchitis virus in day-old broiler chicks

This study reports on the simultaneous administration of live NDV or aMPV subtype B vaccines alongside two live IBV (Massachusetts-H120 and 793B-CR88) vaccines in day-old maternal-antibody positive commercial broiler chicks. In the first experiment, chicks were divided into four groups; one unvaccinated and three groups vaccinated with live NDV VG/GA-Avinew, live H120 + CR88, or VG/GA-Avinew + H120 + CR88. In the second experiment, live aMPV subtype B vaccine was used in place of NDV. Clinical signs were monitored daily and oropharyngeal swabs were taken at regular intervals for vaccine virus detection. Blood was collected at 21 dpv for serology. 10 chicks from each group were challenged with virulent strains of M41 or QX or aMPV subtype B. For IBV, after 5 days post challenge (dpc), tracheal ciliary protection was assessed. For aMPV, clinical scores were recorded up to 10 dpc. For NDV, haemagglutination inhibition (HI) antibody titres were assayed as an indicator of protective immunity. In both experiments, ciliary protection for IBV vaccinated groups was maintained above 90%. The protection against virulent aMPV challenge was not compromised when aMPV, H120 and CR88 were co-administered. NDV HI mean titres in single and combined NDV-vaccinated groups remained above the protective titre (>3 log2). Both experiments demonstrated that simultaneous administration of live NDV VG/GA-Avinew or aMPV subtype B alongside H120 and CR88 vaccines does not interfere with protection conferred against NDV, IBV or aMPV.

Evaluation of transmission potential and pathobiological characteristics of mallard originated Avian orthoavulavirus 1 (sub-genotype VII.2) in commercial broilers

Newcastle disease (ND), caused by Avian orthoavulavirus 1 (AOAV-1), affects multiple avian species around the globe. Frequent disease outbreaks are not uncommon even in vaccinates despite routine vaccination and, in this regards, viruses of diverse genotypes originating from natural reservoirs (migratory waterfowls) play an important role in a disease endemic setting. Though genomic characterization of waterfowl originated viruses has been well-elucidated previously, there is a paucity of data on clinico-pathological assessment of mallard-originated sub-genotype VII.2 in commercial chickens. Hence, the current study was designed to evaluate its transmission potential, tissue tropism and micro- and macroscopic lesions in commercial broilers. Based on complete genome and complete F gene, phylogenetic analysis clustered the study isolate within genotype VII and sub-genotype VII.2 in close association with those reported previously from multiple avian species worldwide. The study strain was found to be velogenic on the basis of typical residue pattern in the F-protein cleavage site (¹¹²R-RQ-K-R↓F¹¹⁷), sever disease induction in chicken, tissue tropism and subsequent clinico-pathological characteristics. Giving a clear evidence of horizontal transmission, a 100% mortality was observed by 4^th and 6^th day post infection (dpi) in chickens challenged with the virus and those kept with the challenged birds (contact birds), respectively. The observed clinical signs, particularly the greenish diarrhea, and macroscopic lesions such as pinpoint hemorrhages in proventriculus and caecal tonsils were typical of the infection caused by an AOAV-1 in chickens. The virus exhibited a broad tissue tropism where genomic RNA corresponding to study virus was detected in all of the tissues collected from recently mortile and necropsied birds. The study concludes that mallard-originated Avian orthoavulavirus 1 is highly velogenic to commercial chicken and therefore ascertain continuous disease monitoring and surveillance of migratory/aquatic fowls to better elucidate infection epidemiology and subsequent potential impacts on commercial poultry.

Polymorphisms of the Chicken Mx Gene Promoter and Association with Chicken Embryos' Susceptibility to Virulent Newcastle Disease Virus Challenge

Newcastle disease is a devastating viral disease of chicken in low- and middle-income countries where the backyard production system is predominant. Marker-assisted selection of chickens that are resistant to Newcastle disease virus (NDV) is the promising strategy that needs to be explored. The aim of the present study was to investigate polymorphisms of the promoter region of the chicken Mx gene and association with Kuroiler, Sasso, and local Tanzanian chicken embryos' survival variability to virulent NDV infection. Chicken embryos were initially challenged with a minimum lethal dose of virulent NDV suspension and then were followed over time to gather information on their survival variability. Using the survival data, high and less susceptible cohorts were established, and a total of 88 DNA samples from high and less susceptible groups were genotypes by sequencing. Five single-nucleotide polymorphisms (SNPs), which were previously reported, were detected. Interestingly, for the first time, the findings demonstrated the association of the promoter region of chicken myxovirus-resistance (Mx) gene polymorphisms with chicken embryos' susceptibility to the virulent NDV challenge. At the genotypic level, the SNP4 G > A mutation that was located within the IFN-stimulating response element was associated (LR: 6.97, P=0.03) with chicken embryos' susceptibility to the virulent NDV challenge. An allele G frequency was higher in the less susceptible cohort, whereas an allele A frequency was higher in the high susceptible cohort. At the haplotype level, the haplotype group ACGC was associated (OR: 9.8, 95% CI: 1.06–79.43, P=0.042) with the same trait and had a resistant effect. In conclusion, the results have demonstrated the association of chicken Mx gene promoter polymorphisms and chicken embryos' survival variability to the virulent NDV challenge, and the information is useful for breeding programs designed to develop chicken genotypes that are resistant to Newcastle disease virus.

Taishan Pinus massoniana pollen polysaccharide inhibits subgroup J avian leucosis virus infection by directly blocking virus infection and improving immunity

Subgroup J avian leucosis virus (ALV-J) generally causes neoplastic diseases, immunosuppression and subsequently increases susceptibility to secondary infection in birds. The spread of ALV-J mainly depends on congenital infection and horizontal contact. Although ALV-J infection causes enormous losses yearly in the poultry industry worldwide, effective measures to control ALV-J remain lacking. In this study, we demonstrated that Taishan Pinus massoniana pollen polysaccharide (TPPPS), a natural polysaccharide extracted from Taishan Pinus massoniana pollen, can significantly inhibit ALV-J replication in vitro by blocking viral adsorption to host cells. Electron microscopy and blocking ELISA tests revealed that TPPPS possibly blocks viral adsorption to host cells by interacting with the glycoprotein 85 protein of ALV-J. Furthermore, we artificially established a congenitally ALV-J-infected chicken model to examine the anti-viral effects of TPPPS in vivo. TPPPS significantly inhibited viral shedding and viral loads in immune organs and largely eliminated the immunosuppression caused by congenital ALV-J infection. Additionally, pre-administration of TPPPS obviously reduced the size and delayed the occurrence of tumors induced by acute oncogenic ALV-J infection. This study revealed the prominent effects and feasible mechanisms of TPPPS in inhibiting ALV-J infection, thereby providing a novel prospect to control ALV-J spread.

Ameliorative effect of synthetic γ-aminobutyric acid (GABA) on performance traits, antioxidant status and immune response in broiler exposed to cyclic heat stress

The aim of this study was to find the effect of synthetic γ-aminobutyric acid (GABA) on the performance, antioxidant status, and immune response in broiler exposed to summer stress. A total of 400-day-old male broiler chickens (Ross 308) was randomly distributed into five treatments (5 replicates). One group served as a control (basal diet only) while the others were supplemented with GABA at the rate of 25 (GABA-25), 50 (GABA 50), 75 (GABA-75), and 100 (GABA-100) mg/kg feed. The experiment was continued for 35 days. Feed intake during the third week was significantly higher (P < 0.05) in GABA-75 and GABA-100, however, it increased significantly (P < 0.05) in GABA-100 during the fourth and fifth week. Overall mean feed intake was significantly (P < 0.05) high in GABA-75 and GABA-100. From the results, we found that body weight improved significantly (P < 0.05) in GABA-50 in week-3. During the fourth, fifth, and overall, body weight increased significantly (P < 0.05) in GABA-100. Significantly, high (P < 0.05) feed conversion ratio (FCR) was found in GABA-100 during the third, fourth, fifth, and on an overall basis. Mean Malondialdehyde (MDA) decreased significantly (P < 0.05) in GABA-100 while Paraoxonase (PON1) and Newcastle disease (ND) titer increased significantly (P < 0.05) in the same group. We concluded that performance traits, antioxidant status, and immune response improved in broiler supplemented 100 mg/kg GABA, exposed to cyclic heat stress.

Experimental infection of IS/885/00-like infectious bronchitis virus in specific pathogen free and commercial broiler chicks

Pathogenesis of an IS/885/00-like (IS/885) strain of variant infectious bronchitis virus (IBV) was examined in one day old specific pathogen free (SPF) and commercial broiler chicks. Chicks were humanely euthanized at 3, 6, 9, 12, 15, 21 and 28 days post infection (dpi) for necropsy examination, and tissues were collected for histopathology and virus detection by reverse transcription polymerase chain reaction (RT-PCR). Respiratory clinical signs and gross lesions consisting of tracheal caseous exudate and plugs, and swollen kidneys (with or without) urate deposits were observed in SPF and broiler chicks. The onset of disease developed more slowly and were of lesser severity in broiler compared to SPF chicks, reflecting the inhibitory effects of the IBV maternal-antibodies in the broiler chicks or genetic/strain susceptibility, or both. Head swelling was observed in one infected broiler chick at 15 dpi and the virus was recovered by RT-PCR and isolation. In the IS/885-infected SPF chicks, cystic oviducts were found in two female chicks. IS/885 was isolated from the cystic fluid. Using ELISA, low to moderate levels of the antibodies to IBV was detected in the SPF compared to broiler infected chicks.

•

Pathogenesis of IBV IS/885 was examined in one day old SPF and broiler chicks.

•

The virus caused respiratory distress, tracheal and kidney lesions in infected chicks.

•

Head swelling was observed in one infected broiler chick at 15 dpi.

•

Cystic oviducts were found in two female SPF chicks.

•

IBV IS/885 examined in this study was pathogenic for both SPF and broiler chicks.

Protection conferred by live infectious bronchitis vaccine viruses against variant Middle East IS/885/00-like and IS/1494/06-like isolates in commercial broiler chicks

The ability of the infectious bronchitis H120 (a Massachusetts strain) and CR88 (a 793B strain) live attenuated vaccine viruses to protect from two Middle East infectious bronchitis virus isolates, IS/885/00-like (IS/885) and IS/1494/06-like (IS/1494) in broiler chicks was investigated. Day-old chicks were separated into three groups, (I) vaccinated with H120 at day-old followed by CR88 at 14 days-old, (II) vaccinated with H120 and CR88 simultaneously at day-old and again with CR88 at 14 days-old, (III) control unvaccinated. At 30 days-old, each of the groups was challenged with virulent IS/885 or IS/1494. Protection was evaluated based on the clinical signs, tracheal and kidney gross lesions and tracheal ciliostasis. Results showed that administering combined live H120 and CR88 vaccines simultaneously at day-old followed by CR88 vaccine at 14 days-old gave more than 80 per cent tracheal ciliary protection from both of the Middle East isolates. In addition, this programme conferred 100 per cent protection from clinical signs and tracheal or kidney lesions. The other vaccination programme, H120 at day-old followed by CR88 at 14 days-old, the tracheal ciliary protection conferred were 60 per cent and 80 per cent from IS/885/00-like and IS/1494/06-like, respectively.

Transmission of infectious bronchitis virus within vaccinated and unvaccinated groups of chickens

The aim of this study was to determine whether vaccination against infectious bronchitis virus (IBV) reduces virus transmission, i.e. to test whether IBV transmission among vaccinated chickens is significantly reduced compared to that among unvaccinated chickens. In two vaccinated and two unvaccinated groups of SPF chickens, a standard measure for virus transmission, the reproduction ratio (R) was determined. R is defined as the average number of new infections caused by one typical infectious individual during its entire infectious period. A single vaccination by eye-drop with IBV H120 reduced the transmission of the IBV challenge virus among the vaccinated chickens (estimated R = 0.69, s.e. = 0.33) significantly (P < 0.05) compared to the transmission among the unvaccinated chickens (estimated R = 19.95, s.e. = 12.41). The possible implications for further study, including selection or development of vaccines are discussed.

Immunomodulatory and hepatoprotective role of feed-added Berberis lycium in broiler chicks

BACKGROUND

A large number of plants and their isolates have been shown to potentiate immunity. Some plants exert anti-inflammatory and anti-stress effects, others hepatoprotective activity. In this study, 320 1-day-old broiler chicks were randomly divided into four major groups A, B, C and D and fed rations supplemented with 0, 15, 20 and 22.5 g Berberis lycium kg⁻¹ ration respectively. Each group was further divided into two subgroups, one vaccinated against Newcastle disease (ND) and infectious bursal disease (IBD), the other non-vaccinated. Antibody titre against IBD and ND, relative weight of lymphoid organs, post-challenge morbidity and mortality, serum hepatic enzymes and total serum protein were observed.

RESULTS

Group C had higher anti-IBD and anti-ND antibody titres. Relative bursa weight in groups C and D was higher until day 28, but birds in group C performed better at later stages of examination. Relative spleen weight was highest in group C. During initial stages there was no effect on relative thymus weight, but at later stages the effect was significant. Groups C and D performed similarly in terms of relative thymus weight. The birds were challenged to field IBD through intramuscular injection at a dose rate of 0.5 mL per bird. Post-challenge morbidity was lowest in groups C and D, while treatment significantly (P < 0.001) affected mortality amongst affected (morbid) birds. Levels of serum alanine aminotransferase and alkaline phosphatase were lowest in group C. Serum protein was similar in all groups and in both vaccinated and non-vaccinated broiler chicks.

CONCLUSION

Berberis lycium added to feed at 20 g kg⁻¹ is effective in improving immunity against ND and IBD as well as liver function in broiler chicks.

Induction of eggshell apex abnormalities in broiler breeder hens

Recently, the causal relationship between eggshell apex abnormalities (EAA) and Mycoplasma synoviae was described. This eggshell pathology has only been documented in table egg layers both spontaneously and experimentally infected with M. synoviae, suggesting that meat-type layers are less prone to this condition. In this study the susceptibility of specified pathogen free (SPF) broiler breeder hens to produce eggs with EAA after M. synoviae infection was assessed. Five groups of 12 hens each were made: a negative control group, a group inoculated intratracheally (i.t.) with a M. synoviae EAA strain at 19 weeks of age, a group inoculated i.t. with this strain at 19 and 26 weeks of age, a group inoculated with M. synoviae i.t. at 19 weeks of age and infected 5 days earlier with infectious bronchitis virus D1466 (IBV), and a fifth group similar to the former but inoculated i.t. twice with an M. synoviae EAA strain at 19 and 26 weeks of age. Eggs with EAA were only produced after a single i.t. inoculation with the M. synoviae EAA strain if preceded by an infection with IBV. The production of eggs with EAA started 6 weeks after M. synoviae EAA inoculation and the proportion of eggs with EAA during the experiment was 9/449 (2%), which was much lower than that in SPF layer hens (14-22%). The present results suggest that broiler breeder hens are less susceptible to producing eggs with EAA after an infection with a M. synoviae EAA strain preceded by an IBV infection, compared with table egg layers. Similar to SPF egg layers, the mean daily egg production per hen was significantly reduced by the M. synoviae EAA strain and there was a general negative effect on eggshell strength by this strain, suggesting it could also have a detrimental effect on hatching egg quality.

Trypsin-induced hemagglutination activity of porcine epidemic diarrhea virus

The hemagglutination (HA) activity of porcine epidemic diarrhea virus (PEDV) was investigated. Two cell-adapted strains of PEDV (KPEDV-9 and SM98LVec) were subjected to HA test against erythrocytes of various origin. Both strains showed HA activity with rabbit erythrocytes only after treatment with trypsin or neuraminidase. Optimal conditions for inducing HA activity of PEDV were 2 h incubation at 37 degrees C using phosphate-buffered saline containing 0.1% BSA. These results suggest that the HA activity of PEDV is most likely caused by proteolytic action on it, which could be developed as a new diagnostic method to rapidly detect and differentiate PEDV infections from other enteric diseases.

Induction of eggshell apex abnormalities by Mycoplasma synoviae: field and experimental studies

A novel eggshell pathology, characterized by an altered shell surface, thinning, increased translucency, and cracks and breaks in the eggshell apex, has become increasingly common in layer flocks of various breeds in The Netherlands. Two field studies found an association between the eggshell apex abnormalities (EAA) and infection with Mycoplasma synoviae. M. synoviae was isolated from the oviduct of birds that produced abnormal eggs, but not from birds in control flocks, although both affected and control birds had agglutinating antibodies against M. synoviae. After a single injection with long-acting oxytetracycline, the production of abnormal eggs ceased, but then reoccurred about 12 days later. A causal relationship between EAA and M. synoviae infection was subsequently demonstrated experimentally. EAA occurred after intratracheal inoculation of birds with M. synoviae, and even more frequently in birds infected with infectious bronchitis virus 5 days before inoculation of M. synoviae. EAA also occurred, although less frequently, in birds inoculated intravenously with M. synoviae and infected with infectious bronchitis virus. EAA did not occur in birds only inoculated intravenously with M. synoviae. M. synoviae was only isolated from the oviducts of birds producing abnormal eggs. The mean daily egg production was reduced in all groups infected with M. synoviae. Examination of the eggshells by scanning electron microscopy revealed that the mammillary layer of the calcified zone was absent and that the inner eggshell membranes were thicker. Isolates of M. synoviae from the oviducts of birds from farms producing abnormal eggs were examined by amplified fragment-length polymorphism analysis and did not appear to be clonal.

Efficacy of aniseed extract as immune stimulant and growth promoter in broiler chicks

Present research was undertaken to investigate the effect of different level of 6% concentrated (w/v) aniseed extract in broiler chicks at NWFP Agricultural University Peshawar Pakistan. One hundred and sixty, day old broiler chicks were randomly assigned to four treatments, as A, B, C, receiving 20, 30 and 40 mL of 6% (w/v) concentrated aniseed infusion and D was kept as control group. Each treatment was replicated four times with ten chicks per replicate. Chicks were reared in cages in an open sided house. Vaccination was done against ND and IBD. Data were recorded for growth performance, immunity and economics. The data were subjected to statistical analysis, using Completely Randomized Design and MSTATC programme. Mean feed and water intake was nonsignificant (p > 0.05). Mean weight gain, FCR and dressing percentage was found better (p < 0.05) in group C. Mean weight of giblet, intestine, breast, fat and thigh was not altered (p > 0.05) in all groups. Mean antibody titer against IBD was higher (p < 0.05) in group C and antibody titer against ND and IB was not altered. Mean percent mortality was found higher (p < 0.05) in group D. Mean feed cost including the cost of aniseed infusion was not influenced (p > 0.05), while the gross return was found better (p < 0.05) in group B and C than other groups. Findings of the research study indicated that group C, receiving aniseed infusion at the rate of 40 ml L(-1) of water shown better growth performance, immunity and gross return. Detail research work is needed to examine the effect of aniseed in ration and its different form of extracts on poultry production under different environmental conditions.

Infectious bronchitis in laying hens: the relationship between haemagglutination inhibition antibody levels and resistance to experimental challenge

In three separate and unrelated experiments, in which vaccinated hens were challenged with virulent infectious bronchitis virus, the ability of individual hens to maintain egg production was related to their serum haemagglutination inhibition antibody titre at the time of challenge. It was found that, regardless of the vaccination programme used, the ability of laying hens to withstand infectious bronchitis virus challenge, as measured by the effect upon their egg production, is directly related to individual antibody titre at the time of challenge. In all three experiments, birds with antibody titres of >/=8 Iog2 (n = 82) did not show a significant reduction in egg production after challenge while those with titres within the range 5-7 log(2) inclusive (n = 126), over a period of 3 or 4 weeks after challenge, showed a significant reduction in their rate of egg lay, viz: 0.38, 0.33 and 0.47 eggs per hen per week, respectively and those with titres <4 log(2) (n = 101) showed, over the same time period, a reduction of 1.0, 0.45 and 1.16 eggs per hen per week, respectively. The ability of different vaccination programmes to stimulate uniformly high antibody responses to infectious bronchitis virus, and hence good overall protection of egg production was compared. It is concluded that the programme of choice is first to vaccinate the birds with a highly attenuated strain of live infectious bronchitis vaccine during rearing (H120), followed by the injection of a potent killed oil emulsion adjuvant vaccine at point-of-lay. The ability of the less attenuated H52 strain of live infectious bronchitis vaccine to interfere with response to killed vaccine was demonstrated in two of the three experiments. In both cases this interference was accompanied by an increased susceptibility of the hens to the effect of infectious bronchitis virus challenge on egg production.

Comparison of the haemagglutination inhibition test and the serum neutralisation test in tracheal organ cultures for typing infectious bronchitis virus strains

Five strains of infectious bronchitis (IB) virus, which had been compared antigenically by the serum neutralisation (SN) test in tracheal organ cultures (OC), were arbitrarily coded and then compared by the haemagglutination inhibition (HI) test. Their antigenic relationships were found to be similar by the two methods but, because of the high and variable cross reactions found in the HI test, the differences between the strains were less clear by that method. It was concluded that the HI test, in its present state of development, is considerably less type-specific than the SN test in OC, and cannot be recommended for defining antigenic relationships between strains of IB virus. However, it retains its value for diagnosing IB or for monitoring the vaccinal status of flocks.

Isolation, characterisation and preliminary cross-protection studies with a new pathogenic avian infectious bronchitis virus (strain PL-84084)

Virological 1 examination of a severe infectious bronchitis (IB)-like field case in laying hens, led to the isolation of a coronavirus antigenically different from Massachusetts, Connecticut and four Dutch IB variant strains. The virulence of the isolate for the fowl, and its dual tropism for the respiratory and genital tracts were demonstrated. In preliminary cross-protection studies Commercial vaccines did not protect against challenge with this isolate. These points and the possible economic significance of the virus are discussed.

Comparison of the enzyme-linked immunosorbent assay (ELISA), haemagglutination inhibition test and agar gel precipitation test for detection of antibodies to avian infectious bronchitis virus

The immune response after vaccination with infectious bronchitis virus (IBV) under field conditions was measured by the ELISA, haemagglutination-inhibition (HI) and agar-gel precipitin (AGP), tests. Vaccinations were performed in three flocks and one experimental group via the drinking water with the vaccine strains H 120 and H 52. In each flock 40 random serum samples were taken every 2 weeks and tested individually. In the experimental group blood samples were collected every week from each of the 10 chickens. The primary vaccination with H 120 resulted in a rapid increase of antibody titre as detected by ELISA followed by a slow decrease over the next few weeks. By the HI and AGP tests no antibody responses could be seen after this primary vaccination. Revaccination with the H 52 strain provoked a further increase in ELISA titres. In the experimental group, and in flock W, a similar increase occurred by the HI test and precipitating antibodies appeared. The formation of HI antibodies in flock T (nipple waterers) was somewhat retarded and precipitating antibodies were just detectable. In flock F revaccination did not result in the immediate production of HI and AGP antibodies. However, 6 weeks after revaccination a significant rise in ELISA, HI and AGP antibodies was observed, probably as the result of a field infection. It was demonstrated that, based on the higher sensitivity, the ELISA test is more suitable than HI and AGP to monitor antibody responses to vaccination against infectious bronchitis. Strain specificity in the HI test is discussed as a reason for its failure to detect antibodies after primary vaccination with the highly attenuated vaccine strain H 120.

Infectious bronchitis in laying hens: interference with response to emulsion vaccine by attenuated live vaccine

Pullet chicks were reared in isolation; all except a control group were variously vaccinated against infectious bronchitis. Individual haemagglutination inhibition (HI) antibody responses were measured from 1 day to 38 weeks old when all birds were challenged with virulent infectious bronchitis virus, and egg production recorded for a further 5 week period. In the controls HI titres remained low until challenge: this caused a loss of 15.1 eggs/hen. In birds injected with oil emulsion killed vaccine (OEV) at 3 and 16 weeks old, the serological response was uniformly high but on challenge the loss in egg production was 2.9 eggs/bird. Birds given H120 live vaccine at 3 weeks and H52 live vaccine at 15 weeks old had a low (23%) individual rate of serological response to the latter, and egg production after challenge was 3.63 eggs/hen less than before. In birds given H120 live vaccine at 3 weeks and emulsion killed vaccine at 16 weeks old, 100% serological response to the latter occurred and egg production was unaffected by challenge. A further group also received H120 and H52 live vaccines at 3 and 15 weeks old respectively: however, they were then subdivided into four groups and injected with emulsion vaccine at either 17, 19, 21 or 23 weeks old. Their response to H52 vaccine was variable. The proportion of birds in each sub-group responding serologically to subsequent vaccination with OEV was 45, 65, 73 and 92% respectively. After challenge egg production in these four sub-groups was reduced by 1.92, 1.15, 0.94 and 1.55 eggs/bird respectively. It is concluded that response to oil emulsion infectious bronchitis vaccine can be impaired if it is used within 8 weeks of H52 live vaccine. Best results are achieved where birds are given a primary dose of H120 live vaccine at 3 weeks old followed by emulsion vaccine 12-16 weeks later. Use of the less attenuated H52 strain of live vaccine before emulsion killed vaccine is contra-indicated.

Active and passive immunisation against nephritis induced by an avian infectious bronchitis virus

Intranasal vaccination with the H120 strain of infectious bronchitis virus (IBV) produced serum neutralisation indices of three or more in nine out of 12 birds. This afforded complete protection against intravenous challenge with the nephritogenic H52 strain of IBV and prevented the multiplication of virus in the kidney. Passive immunisation with homologous convalescent serum protected the kidney but not the respiratory tract against similar challenge. The frequency of virus isolations from the kidney was reduced, the agar gel precipitin response lowered and the haemagglutination inhibition response abolished.

Immunity following inoculation of the H120 and H52 vaccine strains of infectious bronchitis virus into the crop of the domestic fowl

The serological responses and protection associated with inoculation of the HI20 and H52 vaccine strains of infectious bronchitis virus (IBV) into the trachea and directly into the crop of chickens were compared. Intratracheal inoculation at 3 weeks of age with HI20 resulted in the moderate log2 haemagglutination inhibition (HI) titres of 6, previously found to be characteristic of this highly attenuated vaccine strain of IBV. More than 80% of these birds gave a positive reaction to the agar gel precipitin (AGP) test. These precipitin responses had waned in most birds by the time they were re-vaccinated with H52 at 11 weeks of age, when moderate but somewhat higher HI titres of 7 and 8 were obtained and 70% of the birds were AGP-positive. At 15 weeks of age, the inoculates and susceptible controls were challenged intravenously with H52. The intratracheally inoculated birds were fully protected against this challenge which severely damaged the kidneys of 80% of the controls. Crop inoculation of HI20 and H52 failed to produce circulating antibody as measured by the HI and AGP tests. Intravenous challenge, however, showed that the kidneys of 50% of the crop inoculates resisted the challenge which severely damaged the kidneys of 80% of the controls, demonstrating a degree of protection in the absence of circulating antibody.

Comparison of the enzyme linked immunosorbent assay, the haemagglutination inhibition test and the agar gel precipitation test for the detection of antibodies against infectious bronchitis and Newcastle disease in commercial broilers

Serological results as obtained by the agar gel precipitation (AGP) test, haemagglutination inhibition (HI) test (M41, D274, D1466) and an enzyme linked immunosorbent assay (ELISA) from commercial broiler flocks, which had suffered from a clinical infectious bronchitis (IB) infection in the fattening period, were compared with serological findings of control broiler flocks. In addition the Hi-test and ELISA for Newcastle disease (ND) were compared. The AGP results differ significantly between groups. The test had a low sensitivity. The results of the HI-IBV tests were similar for both groups and no difference was seen between flocks with or without clinical IB problems. The IBV ELISA showed a highly significant difference between the two groups. In contrast to the low and not significant correlation coefficients (r) between the IBV HI tests and the ELISA, the value of r between the NDV HI and ELISA was high. The results indicate an ELISA as the preferred test for the diagnosis of IB in broilers.

Detection of Massachusetts and Arkansas serotypes of infectious bronchitis virus in broilers

The objective of this study was to compare the presence of the Arkansas (Ark) and Massachusetts (Mass) serotypes of infectious bronchitis virus (IBV) in the tracheas and cecal tonsils of commercial broilers after vaccination at 1 day of age by coarse spray. When given as a single serotype vaccine, the Mass strain was detected by reverse transcriptase-polymerase chain reaction (RT-PCR)-restriction fragment length polymorphism (RFLP) only in the tracheas, whereas the Ark strain was detected in both the tracheas and cecal tonsils. By in situ hybridization, the Mass and Ark nucleocapsid (Nc) genes were detected only at 7 days in the tracheas. When both strains were given in the mixed vaccine, the Mass strain was more consistently detected by RT-PCR-RFLP in the tracheas and cecal tonsils at early stages of infection (up to 14 days) and the Arkansas strain was more consistently detected at late stages of infection (21 and 28 days). By in situ hybridization, the IBV Nc gene was more consistently detected in the trachea at early stages of infection (7, 14, and 21 days) and in the cecal tonsils at late stages of infection (21, 28, and 35 days). In general, the Mass strain was more frequently recovered from the tracheal and cecal tonsil tissues at earlier stages of infection and the Ark strain was recovered at later stages of infection.

Effect of IBV-H120 vaccination in broilers on colibacillosis susceptibility after infection with a virulent Massachusetts-type IBV strain

Vaccination against infectious bronchitis (IB) is aimed to protect against clinical IB. The question is, however, whether vaccinated birds are also protected against predisposure for colibacillosis after a subsequent IBV infection. We examined this research question in four experiments. One-day-old commercial broilers, housed in isolators, were vaccinated with IB vaccine strain H120 by coarse spray or ocularly. Twenty-eight days after vaccination, broilers were challenged with the virulent IBV strain M41. Five days later, broilers were inoculated with Escherichia coli strain 506. Body weight uniformity, severity of E. coli airsacculitis, and systemic E. coli infection at 7 days following E. coli inoculation were used as parameters for colibacillosis. IBV vaccination reduced both the number of broilers with E. coli airsacculitis as well as the severity of airsacculitis significantly after challenge with IBV-M41 and E. coli 506. However, in spray-vaccinated groups, no significant reduction of the number of birds with systemic colibacillosis or the severity of this infection was obtained, and body weight uniformity was not significantly improved compared with nonvaccinated, IBV-M41, and E. coli 506-challenged groups. Eye-drop vaccination resulted in conflicting results.

Aerosol-inducedMycoplasma synoviaearthritis: the synergistic effect of infectious bronchitis virus infection

The effect of infectious bronchitis virus (IBV) infection (10(4.5) median embryo infective dose per chick) on the induction of Mycoplasma synoviae arthritis was investigated. Mycoplasma-free brown layer pullets, approximately 5 weeks old, were exposed to an aerosol dose of > or =10(2-3) colony-forming units (CFU) of M. synoviae alone or 3 days after inoculation of a field strain of IBV (D1466) by the ocular-nasal route. Chicks injected intravenously with 10(9) CFU M. synoviae served as positive controls. Thirty-one per cent of chicks receiving M. synoviae aerosol alone developed arthritis compared with 50% of those co-infected with IBV. Ninety-five per cent of positive control birds developed arthritis. In a repeat experiment an additional group was exposed to M. synoviae aerosol 3 days after infection with IBV M41 strain. These birds also received two aerosol doses of M. synoviae 14 days apart (> or =10(0-1) CFU/bird initially and > or =10(1-3) after 14 days). Chicks injected intravenously with 10(6) CFU M. synoviae acted as positive controls. Fifty per cent of the positive controls were re-inoculated intravenously (10(8) CFU) after 14 days. Twenty-one per cent of chicks infected with M. synoviae aerosol developed arthritis compared with 33% of those co-infected with IBV D1466, and 55% of those co-infected with IBV M41. After the single intravenous, low-dose M. synoviae inoculation 11% of birds developed joint lesions, whereas 70% of those receiving the second inoculation developed lesions. These results suggest that IBV may enhance M. synoviae arthritis after aerosol exposure and that the incidence of joint pathology depends on the strain of IBV.

Characterization of an avian infectious bronchitis virus isolated in China from chickens with nephritis

One IBV isolate, SC021202, was isolated from the kidneys of the infected young chickens by inoculating embryonated eggs, and its morphology, physiochemical and haemagglutonating properties were detected. Virulence of the isolate SC021202 was determined with specific pathogen‐free (SPF) chicken inoculation. Nucleotide acid sequence of S1 gene of the isolate SC021202 was further sequenced and analysed. The physiochemical and morphological properties of the isolate SC021202 were in accordance to that of typical infectious bronchitis virus (IBV). In a pathogenicity experiment, the clinical signs and related gross lesions resembling those of field outbreak were reproduced and the virus isolate SC021202 was re‐isolated from the kidneys of the infected chicken. Sequence data demonstrated that the full length of the amplified S1 gene of the isolate SC021202 was composed of 1931 nucleotides, coding a polypeptide of 543 amino acid residues. Compared with IBV strains from GenBank, the nucleotide and deduced amino acid sequence of S1 gene of the isolate SC021202 shared 60.0–91.4% and 49.1–88.9% identities, respectively. A nucleotide fragment of ′CTTTTTAATTATACTAACGGA′ was inserted at nucleotide site 208 in the S1 gene of the isolate. These results indicated that IBV isolate SC021202 was a new variant IBV isolate and responsible for field outbreak of nephritis.