Intermediate Plus Research Articles

Cytokines, Serological, and Histopathological Assessment of Recombinant Vaccination Strategies for Combatting Infectious Bursal Disease in Broiler Chickens.

Infectious bursal disease (IBD) represents a greatly transmissible viral disease found worldwide, causing significant health and production challenges in young chickens. The aim of this research was to assess the immune reaction induced by different vaccines targeting IBD. These vaccines included recombinant (Vac1; HVT-IBD vector), immune complex (Vac2; Bursa-Plex®), and intermediate plus (Vac3; Bursine plus) IBD vaccines. Our assessment relied on serological and histopathological analyses, as well as the pattern of immune-related cytokine expression in the bursal tissue. The vaccinated groups, along with a control positive (CP) group, were subjected to a vvIBDV challenge on their 28th day of life, while the control negative (CN) group received a mock vaccination with PBS. Our study revealed that Vac1 resulted in the most favorable growth performance, as well as maintained normal liver and kidney function, mitigating the impact of IBDV infection. Serological analysis using VP2 ELISA kits indicated that Vac1 induced the strongest immunological response among all vaccines. Histopathological examination demonstrated that Vac1 caused minimal lymphoid depletion observed in the lymphoid organs, followed by Vac2. Analysis of cytokine expression profiles showed significant upregulation in all vaccinated groups, particularly Vac1, during the pre-challenge period. Following IBDV infection, Vac1 resulted in a noteworthy increase in the expression of IL2 and IFN-γ, Vac2 showed a significant upregulation in TNF-α and granzyme, and both Vac1 and Vac3 exhibited increased levels of IL1β and IL10. In conclusion, our study suggests that the various vaccines triggered immune responses against IBD through both humoral and cell-mediated immunity. However, recombinant followed by immune complex vaccines appeared to induce more robust immunity while also being safer for broiler chickens in contrast to the intermediate plus vaccine.

Effect of Intermediate Plus Vaccine and vvIBDV on Bursa Secretory Cells and Their Glycoprotein Production.

There are two types of secretory cells in the chicken bursa of Fabricius (BF): (a) interfollicular epithelial cells (IFE), and (b) bursal secretory dendritic cells (BSDC) in the medulla of bursal follicles. Both cells produce secretory granules, and the cells are highly susceptible to IBDV vaccination and infection. Before and during embryonic follicular bud formation, an electron-dense, scarlet-acid fuchsin positive substance emerges in the bursal lumen, the role of which is unknown. In IFE cells, IBDV infection may induce rapid granular discharge, and in several cells, peculiar granule formation, which suggests that the glycosylation of protein is injured in the Golgi complex. In control birds, the discharged BSDC granules appear in membrane-bound and subsequently solubilized, fine-flocculated forms. The solubilized, fine-flocculated substance is Movat-positive and can be a component of the medullary microenvironment, which prevents the medullary B lymphocytes from nascent apoptosis. Vaccination interferes with the solubilization of the membrane-bound substance, resulting in: (i) aggregation of a secreted substance around the BSDC, and (ii) solid lumps in the depleted medulla. The non-solubilized substance is possibly not "available" for B lymphocytes, resulting in apoptosis and immunosuppression. In IBDV infection, one part of the Movat-positive Mals fuse together to form a medullary, gp-containing "cyst". The other part of Mals migrate into the cortex, recruiting granulocytes and initiating inflammation. During recovery the Movat-positive substance appears as solid, extracellular lumps between the cells of FAE and Mals. Possibly the Mals and Movat-positive extracellular lumps glide into the bursal lumen via FAE to eliminate cell detritus from the medulla.

Immunopathological comparison of in ovo and post-hatch vaccination techniques for infectious bursal disease vaccine in layer chicks.

This study was designed to compare immunopathological effects of in ovo vaccination with post-hatch vaccination against IBD in White Leghorn chicks. A total of 189 embryonated eggs were divided into six groups. At day 18 of incubation, groups A–C were administered in ovo with 228E, Winterfield 2512:10/3 and 2512/90:10/2.7, respectively, group D (post-hatch vaccination) and group E as shamed control (for quality evaluation of in ovo vaccination technique), and group F as control. The results showed that antibody titers against IBD detected by ELISA on days 2, 17, and 28 were significantly higher in all in ovo groups as compared to control groups E and F. On day 17, all vaccinated groups (in ovo and post-hatch vaccinated) showed no significant differences in antibody titers among themselves; however, at day 28, only the post-hatch group showed significantly higher antibody titers followed by in ovo vaccinated groups. The cell-mediated immunity determined by PHA-P assay was significantly higher in all vaccinated groups than the non-vaccinated groups. No clinical signs of IBD infection were observed in any of the vaccinated groups. There was only increase in bursa size of groups vaccinated with intermediate plus strains (groups A, C, and D) at day 28. The histopathology showed that all the treatment groups had mild lesions induced by IBD virus in bursa. This study concluded that in ovo vaccination with live IBD vaccines provides protective immunity to the chickens even in the presence of IBD-specific MDA; therefore, the onset of immunity was much earlier than the post-hatch vaccination and in ovo groups also maintained protective immunity against IBD for longer time.

Co-administration of toll-like receptor (TLR)-3 agonist Poly I:C with different infectious bursal disease (IBD) vaccines improves IBD specific immune response in chicken.

Toll-like receptor (TLR) agonists are emerging as promising vaccine adjuvants and immunomodulators in poultry against many diseases. Infectious bursa disease (IBD) still remains as a major threat to poultry industry. Improving the vaccine mediated immune response would help in better protection against IBD virus infection. Adjuvant potential of TLR3 agonist, Polinosinic polycytidylic acid (Poly I:C) with different IBD vaccines has been analyzed in chicken in the present study. Intermediate, intermediate plus IBD vaccine, bursaplex vaccine and their respective poly I:C combinations were used for immunization of chicken. IBD specific antibody titers, bursa to body weight ratio, body weight gain and bursal lesion scores were evaluated at weekly interval in different immunization groups. Fold changes in cytokines IL-1β and IFN-γ mRNA expression levels in spleen were also analyzed in different groups. Intermediate plus IBD vaccine induced significantly (P ≤ 0.05) higher IBD specific antibody response at 35days of age than other groups with comparatively lower body weight gain and moderate bursal lesion score. Poly I:C co-administration with intermediate IBD vaccine and bursaplex vaccine improved the IBD specific antibody titers, better body weight gain and moderately less bursal lesion score. However, Poly I:C combination with intermediate plus IBD vaccine did not improve the specific immune response. IL-1β levels were up-regulated in intermediate plus and bursaplex group, whereas IFN-γ m RNA expression levels were upregulated in intermediate IBD with Poly I:C group. In conclusion, poly I:C co-administration with intermediate IBD and bursaplex vaccine was beneficial and improved the specific immune response with least immunosuppression and bursal damage.

Safety and Efficacy Profile of Live, Intermediate Plus Vaccine Against Infectious Bursal Disease Based on Strain G6.

Infectious bursal disease (IBD) is an acute, highly contagious, immunosuppressive disease of young chickens that causes considerable economic loss in the poultry industry worldwide. Vaccination with live attenuated vaccines is still the most important method used for the control and prevention of IBD in chickens. Here we present the results of in vitro characterization, as well as efficacy and safety testing of a live, intermediate plus vaccine against IBD based on strain G6. Strain characterization confirmed that G6 strain is an intermediate plus strain, showing a high degree of homology with the existing vaccine strains of the same virulence. Safety studies showed that chickens can be vaccinated from 10 days of age. Onset and duration of immunity in specific pathogen free and maternally derived antibodies (MDA) chickens was proven to be 14 and 35 days after vaccination, respectively. When immunizing MDA-positive chickens, vaccine is capable of breakthrough at a titer of ≤500 ELISA units. The field trial conducted on commercial broilers showed a 95% protection against vvIBDV challenge. Stability of the freeze-dried vaccine after reconstitution was confirmed over a period of 3 h. Overall, IBD G6 vaccine has shown good safety and efficacy profile in accordance with European Pharmacopoeia requirements.

Decay pattern of maternally derived antibodies and antibody response of infectious bursal diseases live vaccine

Introduction: Repeated outbreaks of infectious bursal disease (IBD) despite vaccination necessitated this study. Methods: The right age of IBD vaccination, the immunogenicity and the strain of the vaccine were established. Boven gold pullets (n = 150) were used. They were grouped into 6 groups; unvaccinated and vaccinated chicks according to weeks of blood sampling. Both antibodies titres (unvaccinated and vaccinated) were determined by enzyme- linked immune sorbent assay (ELISA). Results: In broiler chicks, the maternally-derived antibodies (MDA) titre decayed from 1,500 ELISA titre at day old to zero at 35 days , while the antibody rose from a titre of 500 at day old to titre of 2000 at 40 days following vaccination and intercepted at a titre of 700 at 21 days. In pullet chicks, the MDA started with an ELISA titre of 1,500 at day old to zero at 38 days of age, while antibodies rose from a titre of 1,100 at day old to 2,000 at 35 days, and then intercepted at a titre of 800 at 22 days of age, hence the breakthrough titre of the live vaccine for pullet chicks. Significance: MDA for broiler and pullet chicks for the chicks from this hatchery completely decayed at 35 and 38 days, respectively and intercepted at a titre of 700. Thus, the chicks should be vaccinated at 21 and 22 days, respectively. Also, poultry farmer should not use the same vaccination days for chicks of different hatchery. The breakthrough titre of the vaccine was 700. Therefore, it is an intermediate plus. The decay was faster in broilers than pullets, hence vaccination days should be early in broilers than pullets.

Comparative Evaluation of Live Vector, Immune Complex and Intermediate Plus Vaccines of Infectious Bursal Disease in Broiler Chicken

Comparative Evaluation of Live Vector, Immune Complex and Intermediate Plus Vaccines of Infectious Bursal Disease in Broiler Chicken

Infectious bursal disease: outbreak investigation, molecular characterization, and vaccine immunogenicity trial in Ethiopia.

The study was conducted with the objective of isolation and molecular characterization of infectious bursal disease virus (IBDV) circulating in Ethiopia and to assess the immunogenicity of different commercially available live attenuated IBD vaccines and finally to select the appropriate vaccine strain for the existing IBDV. Outbreak samples collected from different poultry farms with IBD infection between 2013 and 2015 were used for the virus isolation and molecular characterization. IBD vaccine immunogenicity test was conducted using four different commercially available live attenuated IBD vaccine strains: namely D78, B2K, LC75, and EXTREM. Day-old Bowman brown chickens purchased from commercial farm in Debre Zeit were used for the experiment. Serum samples were collected at days 14 and 21 and screened for the presence of maternal IBDv antibodies. The screening test result revealed that most of the chickens from vaccinated progeny were positive at the age of day 14 with mean antibody titer of .42, but declined at day 21 to 0.049 below cut-off point (S/P<0.3). Chickens were divided into five different groups (four vaccinal and one control) and vaccinated at the age of day 21 and boosted after 14days. Serum samples were collected and all of them were challenged at their 42days of age with locally isolated very virulent infectious bursal disease virus (vvIBDV). From four of the vaccine strains used for immunogenicity study, the intermediate plus strains (LC75 and EXTREM) found to be superior and efficiently cross protect against the challenge with locally isolated vvIBDV. The development of clinical signs was studied and post-mortem examinations were conducted both on dead and sacrificed birds. From a total of 25 tissue samples processed for virus isolation on chicken fibroblast cell culture, 95% (18/20) of bursa and 80% (4/5) of the spleen samples showed visible cytopathic effect (CPE). The positive samples were tested by PCR and 19 of them had the expected band (643bp). Further 11 representative samples were sequenced and confirmed that the circulating virus among poultry population in the country is vvIBDV. The study has recommended to produce vaccine using intermediate plus strains to prevent and control currently circulating vvIBDV.

English

The objective of the present study was to identify the significance of the Bursal-Body index (BB index) as a tool in assessing the health status of a chicken flock especially those under experimental condition. With the unending debate on the bursa of Fabricius as a diagnostic tool, a total of 135 day-of-hatch Dominant black Cockerel hybrid were housed in six separate houses with positive pressure and filtered airflow. Houses were assigned to the three vaccines (two intermediate (A, and C), and one intermediate plus (B) vaccine strain), a challenge group (D) and control group (E). The birds were vaccinated according to manufacturer&rsquo;s directives on day 17th post hatch; challenge group was inoculated with 0.05 ml of very-virulent isolate of the infectious bursal disease virus (vvIBDV) on the same day. On day(s) 1, 2, 3, 4, 5, 7, 10, 14 and 21 post vaccination/challenge (Dpv/c) three birds were humanely sacrificed from each group with Bursal-Body ratio (BB ratio) and Bursal-Body index (BB index) recorded. The values (&gt;0.7, that is, no atrophy (mild vaccine); 0.3-0.7 (relative or transient atrophy (for intermediate or intermediate plus vaccine) and &lt;0.3 for a strong atrophy (hot vaccine or infection with vvIBDV) were recorded conforming to the first described standard, and there was not a statistical difference (p&gt;0.05) observed between the groups. This indicating that BB index could be used as a tool in assessing the health status of a flock. Key words: Avian, Bursa of Fabricius, bursal-body index (BB index), infectious bursal disease (IBD).

Determination of the serum antibody level of different age groups of broiler chicken against Infectious Bursal Disease (IBD)

A study on Infectious Bursal Disease (IBD) was conducted on broiler chicks (N=200+70) of strains: Cobb-500 and Hubbard classic at Laxmipur district of Bangladesh. The blood sample were collected at day old chicks (1st day), pre-vaccinated flocks (11th day) and post-vaccinated flocks (26th day), to measure the antibody titer by indirect ELISA method. Maternal derived antibody (MDA) mean titer of day old chicks (N=40) were found 9621.65 ± 780.78 and 4232.60 ± 301.66 for Cobb-500 and Hubbard classic respectively. MDA mean titer was measured at day eleven chicken (N=60) before vaccination and found 1963.00 ± 143 and 984.16 ± 126.4037 respectively. Of these two titers; Cobb-500 strain was found to be protective (&gt;1000) where Hubbard classic was below protective (&lt;1000) titer level. The two flocks of Cobb-500 and Hubbard classic strains of broiler chickens were vaccinated with intermediate (Bursine-2) and intermediate plus (IBD Blen) vaccine respectively at day twelve and serum was harvested on day twenty six. The mean serum titers were found 131.30 ± 36.04 and 7413.54 ± 569.39 in Cobb-500 and Hubbard classic respectively, where mean titer level of Cobb-500 was below the minimum protective level but Hubbard classic strain was developed 7413.54, protective level. These results were indicating that the maternal derived antibody titer persists above 1000 level hindering the development of antibody titer in vaccinated flocks. However, persistence of MDA titer above 1000 may causes of vaccination failure of IBD vaccine.International Journal of Natural Sciences (2014), 4(2) 22-27

Comparative Studies between Different Types of Live Infectious Bursal Disease (IBD) Vaccine Strains in Egypt

This study was carried out to test the efficacy of different live infectious bursal disease (IBD) vaccines (intermediate; classical or intermediate plus) for controlling IBD or as it is more commonly known in Egypt as gumboro disease problems in the Egyptian poultry field. The efficacy of different living attenuated commercial vaccines were applied in ten groups of (20) Specific Pathogen Free chicks (SPF) for monitoring the immunosuppression effect. The immune response were determined in nine groups of (75) two weeks old SPF chicks “for each group” in vitro by measuring Enzyme Linked Immuno-Sorbent Assay (ELISA) and Serum Neutralization Test (SNT) titer post vaccination with estimation of bursal /body weight ratio and histopathological examination of bursa of fabricious; then in vivo by challenging birds with 10 3.5 EID50 / dose challenge IBD virus strains (variant; classical and very virulent strains). Results revealed that; protection percentages were ranged between 90%-100% in birds vaccinated with intermediate or intermediate plus IBD vaccine and between 90%-95% in birds vaccinated with invasive intermediate Bursa B2K. While birds vaccinated with classical D78 gave protection 95%-100% with highest antibody ELISA mean titer and SNT were “11344 and 1024”; respectively. This confirms that under field condition, poultry industry can be protect from gumboro disease if using commercial IBD vaccine

Evaluation of immune responses by live infectious bursal disease vaccines to avoid vaccination failures.

Infectious Bursal Disease (IBD) is a viral, contagious immunosuppressive disease posing an important threat to the commercial poultry industry. Evolution of highly virulent strains of IBD virus warranted the need for detailed characterization of the immune responses offered by the currently available vaccines. Two extensively used live vaccines of varied attenuation levels - intermediate and intermediate plus - strains were analyzed for the induction of immune responses. Both the vaccines induced protective antibody titers with the onset, quicker and higher with the intermediate plus vaccine. The intermediate plus strain vaccinate was observed to induce higher levels of IFN-γ in the birds. These results were supported by immunophenotype analyses with an increase in CD8+ and simultaneous decrease in CD4+ cell population. Both vaccine strains conferred protective immunity against virulent challenge. The study warrants the use of intermediate plus vaccines in disease endemic regions and intermediate vaccines in non-endemic regions to prevent IBD infection.

Recurrent outbreaks of infectious bursal disease (IBD) in a layer farm caused by very virulent IBD virus (vvIBDV) in India: Pathology and molecular analysis

The present study was carried out to investigate and characterize the nature of infectious bursal disease virus (IBDV) involved in the recurrent outbreaks in an experimental layer farm in Bareilly, Uttar Pradesh, India using direct tissue reverse transcription- polymerase chain reaction (RT-PCR) followed by nucleotide sequencing of VP2 gene. A total of three acute IBD outbreaks with the interval of 4-6 months were recorded in the batch of 3-5 weeks-old layer chicks in the year 2012-2013. Tissues collected from necropsied birds were found RT-PCR positive for IBDV VP2 gene. Genetic analysis of the sequenced VP2 gene revealed the IBDV belonged to very virulent (vv) subtype and had amino acids at positions 222A, 256I, 294I, and 299S typical for vvIBDV strains isolated worldwide. It had only one unique amino acid change in the antigenic peak A (210-225 aa) at position 212DàN (AspàAsn), which is not observed in any of the vvIBDVs isolated in India and abroad. Phylogenetic analysis revealed the isolates were more closely related to vvIBDV strains rA and rB (U.S.A.), Gx and HLJ-7 (China), OKYM (Japan), and shared &gt;95% nucleotide homology with them. The VP2 gene shared 96.7% amino acid homology with IBDI+ vaccine strain used in India, comparatively higher among other vaccines strains, suggesting that IBD intermediate plus (IBDI+) vaccine might provide optimum cross protection, also for other vvIBDV strains. The vvIBDV strains remain a threat to poultry industry worldwide, and require regular monitoring and genetic analysis in order to keep track of the appearance and evolution of antigenically different IBDV strains or subtypes.

Evaluation of live gumboro vaccine prepared from local variant strain for control of infectious bursal disease in Egypt

Aim: The present study was designed to evaluate live Gumboro (IBD) vaccine prepared from local variant isolated strain (Egy-IBD Var 2009 Vp2 gene-, partial cds submitted in gen bank at accession no. : JN 118617) for controlling IBD problem in Egypt. Material and Methods: Local isolated variant strain was adapted on Baby Grivet Monkey kidney cell line -70(BGM-70) 7.5 4.5 used for preparation of tissue culture (T.C) live vaccine. T.C IBDV had a titer of 10 TCID /ml (10 TCID per dose) after 50 50 five passages in BGM-70 cell culture. Evaluation of prepared vaccine was done in vitro by measuring ELISA, and in vivo by protection % against very virulent or variant field IBD isolated strains. Result: Evaluation revealed that the prepared vaccine was safe; sterile; pure; non-immunosuppressive; and efficient. The Geometric Mean Titer (GMT) of ELISA for the prepared vaccine was 8271 and more than 10000 in compared with different commercial IBD vaccines; while protection percentage gave 96-100%; 92-96% and 96-98% in groups vaccinated with commercial (intermediate; intermediate plus and classical) IBD vaccines; respectively in compared to 96-100% in group vaccinated with local prepared vaccine when challenged with very virulent or variant IBD isolated strains. Conclusion: We can use live T.C. IBD vaccine prepared from local variant isolated virus strain as method for control IBD disease in Egypt.

IMMUNOGENIC RESPONSE WITH EFFICACY OF CERTAIN GUMBORO VACCINES IN BROILER

The research work was carried out to determine the immunogenic response with efficacy of six commercial Gumboro, vaccines (Nobilis® Gumboro D78 and Nobilis® Gumboro 228E, Intervet, The Netherlands; Bur-706®, Merial, France; TAD Gumboro vac® and TAD Gumboro vac forte®, Lohmann Animal Health, Germany; BursaplexTM, Merial Select, Inc. Gainesville, USA) under experimental condition in broiler chickens during the period from November 2002 to May 2003. The chickens of two groups were vaccinated with Nobilis® Gumboro D78 and Nobilis® Gumboro 228E at 14 days of age with a booster dose at 21 days of age and were challenged at 40 days of age with vvIBDV. TAD Gumboro vac® and TAD Gumboro vac forte® were inoculated into the two groups of chickens at 14 and 28 days of age and the chickens were challenged at 35 days of age with vvIBDV. Bur-706® vaccine was given to the chickens of another group at one-day-old and 14 days of age and the chickens were challenged at 28 days of age. One group of chickens was vaccinated with Bursaplex™ vaccine at 1-day-old with no booster dose and was challenged at 21 days of age. The percentage of protection in birds receiving Nobilis® Gumboro D78 and Nobilis® Gumboro 228E vaccines by intraocular route was 92.30 and 96.29 respectively, whereas the percentages of protection in birds receiving TAD Gumboro vac®, TAD Gumboro, vac forte® and Bur-706® vaccines were 95.65, 100 and 95.83 respectively. BursaplxTM provided 100% protection against challenge with vvIBDV. Chickens vaccinated with Nobilis® Gumboro D78, Nobilis® Gumboro 228E, TAD Gumboro vac®, and Bur-706®, showed significant (p &lt; 0.05, p &lt; 0.01) decrease in ELISA antibody titre up to the day of challenge infection. BursaplexTM vaccinated group also showed significant decrease in ELISA antibody titre by 7 days (p &lt; 0.05) and by 14 and 21 days (p &lt; 0.01) after primary vaccination. In case of TAD Gumboro vac forte®, 7 days (839 ± 219.34) and 14 days (258 ± 44.80) after primary vaccination, the ELISA antibody titre significantly (p &lt; 0.01) decreased but 7 days after booster vaccination, the ELISA antibody titre significantly (p &lt; 0.01) increased (1299 ± 37.51). All the control sera revealed significant (p &lt; 0.01) decrease of ELISA antibody titre up to day of challenge infection. There was an insignificant increase in ELISA antibody titre 7 days after booster vaccination in case of unvaccinated control groups for TAD Gumboro vac® and TAD Gumboro vac forte® only. Nobilis® Gumboro D78, TAD Gumboro vac® and Bur-706® vaccinated groups revealed significant (p &lt; 0.01) increase of ELISA antibody titre 7 days post-challenge while Nobilis® Gumboro 228E and BursaplexTM vaccinated groups showed significant (p &lt; 0.05) increase of antibody titre after 7 days of challenge. Insignificant increase of antibody titre was recorded in TAD Gumboro vac forte® vaccinated group. It may be concluded that TAD Gumboro vac forte® (intermediate plus) and BursaplexTM (Merial Select, Inc. Gainesville, USA) can be used to immunize the broiler birds sufficiently against IBD. However, it is necessary to estimate the optimum vaccination timing, i.e., to determine when maternal antibodies in chicks will decline to levels that the vaccines can overcome.

Protective efficacy of commercial live vaccines against very virulent infectious Bursal disease virus (vvIBDV) in Ghana

In spite of the intensive and varied vaccination procedures to control Infectious Bursa Disease (IBD), the emergence of a very virulent (vv) IBD pathotype in Ghana has led to high economic losses in the poultry industry. The potencies of two live intermediate IBD vaccine strains (TAD and Nobilis D78) and an intermediate-plus (hot) vaccine strain (228E) used in Ghana were evaluated by challenging Specific Antibody Negative (SAN) chicks with a vvIBD virus (LV/G19) which was recently isolated in Ghana. Serum samples were obtained from all chicks before vaccination and virus challenge. Antibody titres were measured by Enzyme-linked Immunosorbent assay (ELISA). Body weight, bursal weight and bursa to body weight measurements were also taken. All vaccinated chicks were fully protected from the vvIBD virus, as neither morbidity nor mortality was observed in the vaccinated chicks after challenge. The intermediate–plus (hot) IBD vaccine elicited the highest antibody titers but caused reduction in the size of the bursa of Fabricius. Taken together, the results of this study showed that vaccines currently in use in Ghana can protect chicken against the locally-isolated vvIBD virus. Key words: Infectious bursal disease, vaccine efficacy, intermediate, intermediate-plus (hot).

Gross histological changes in some lymphoid organs in broilers after vaccination against infectious bursal disease

This study was designed to detect the reactions grossly and histologically on the lymphoid organs (Bursa of Fabricious, Spleen, Thymus) in 8 day old broiler chickens vaccinated with infectious bursal disease vaccine (Intermediate plus)-(Ceva- IBDL).The study revealed no clinical signs on post vaccination days 2, 4 and 6. Gross lesions were swelling of the bursa due to the edema which obviously appeared as yellowish transudate covering the serosal surface area, and the bursa appears congested, the longitudinal striation on the surface become more prominent and congested while small gray foci appear on the surface of spleen. Microscopically there is degeneration and necrosis of lymphocytes in the medullary area and lymphoid follicles, edema between lymphoid follicles, hyperemia, lymphocytic depletion and cystic cavities developed in the medullary area of the follicles. In spleen, there were degeneration and necrosis of reticuloendothelial cells in the germinal center of the white pulp, with hyperemia in spleen and thymus. It was concluded that the intermediate plus vaccine which used in this study induced severe pathological changes in the bursa and spleen and less in the thymus on post vaccination days 2, 4 and 6.

EVALUATION OF ANATOMOPATHOLOGICAL, SEROLOGICAL, IMMUNOLOGICAL RESPONSES AND PROTECTION IN BROILERS VACCINATED WITH LIVE INFECTIOUS BURSAL DISEASE VACCINES

ABSTRACT The study was divided into three experiments. In the first one, broilers were distributed into six groups and vaccinated against infectious bursal disease at 14 days of age: T1-not vaccinated, T2-Lukert1 (intermediate), T3-Lukert2 (intermediate plus), T4-228E, T5-V877 and T6-Winterfield 2512 (“hot” strains). Bursas of Fabricius (BF) were collected at 17, 21, 28 and 35 days to measure BF relative weight (BFRW), diameter, histological examination and image processing analysis (IPA). At one, 14, 21, 28 and 35 days of age, samples of blood taken from eight birds from each group for serology analysis by ELISA test. Hot strains vaccines induced reduction of BFRW and BF diameter, higher histological score lesion degree, more lymphocyte depletion on the BF follicles and higher IBD antibody titer. In the second experiment, 16 birds from groups T1 to T6 were isolated and challenged with a very virulent strain of IBDV (vvIBDV) at 25 days of age. Only groups T4, T5 and T6 were totally protected against vvIBDV challenge. In the third experiment, the immunosuppressive potential of each vaccine was determined by examining the ability of IBDVvaccinated birds to respond to Newcastle disease (ND) vaccination and challenge. None of the vaccines was found to be immunodepressive.

Bilateral Effects of Vaccination Against Infectious Bursal Disease and Newcastle Disease in Specific-Pathogen-Free Layers and Commercial Broiler Chickens

Different infectious bursal disease virus (IBDV) live vaccines (intermediate, intermediate plus) were compared for their immunosuppressive abilities in specific-pathogen-free (SPF) layer-type chickens or commercial broilers. The Newcastle disease virus (NDV) vaccination model was applied to determine not only IBDV-induced immunosuppression but also bilateral effects between IBDV and NDV. None of the IBDV vaccines abrogated NDV vaccine-induced protection. All NDV-vaccinated SPF layers and broilers were protected against NDV challenge independent of circulating NDV antibody levels. Sustained suppression of NDV antibody development was observed in SPF layers, which had received the intermediate plus IBDV vaccine. We observed a temporary suppression of NDV antibody development in broilers vaccinated with one of the intermediate, as well as the intermediate plus, IBDV vaccines. Different genetic backgrounds, ages, and residual maternal antibodies might have influenced the pathogenesis of IBDV in the different types of chickens. Temporary suppression of NDV antibody response in broilers was only seen if the NDV vaccine was administered before and not, as it was speculated previously, at the time the peak of IBDV-induced bursa lesions was detected. For the first time, we have demonstrated that the NDV vaccine had an interfering effect with the pathogenesis of the intermediate as well as the intermediate plus IBDV vaccine. NDV vaccination enhanced the incidence of IBDV bursa lesions and IBDV antibody development. This observation indicates that this bilateral effect of an IBDV and NDV vaccination should be considered in the field and could have consequences for the performance of broiler flocks.

Admission Criteria as a Predictor of Academic Performance in a Management Programme

Most of the autonomous B-Schools in India prescribe very stringent admission criteria for entry into their programmes. However the typical criteria consist of three components of evaluation-Written Test, Group Discussion (GD) and Personal Interview (PI). Some of the schools even use Graduation Score, Psychometric tests, written analysis tests, Calligraphy tests along with the regular Written Test, GD & PI. There had been many studies particularly in the US to examine to what extent the components of admission criteria predict the academic success. GMAT and Under Graduate Grade point Average (UGPA) were the strongest predictors of the Graduate Grade Point Average. However the explanatory power of GMAT and UGPA were reasonably low. This study includes the student performance in GD, PI, Intermediate (Plus 2) and Matriculation (SSC) as the explanatory variables apart from the Written Test and Graduate level performance-most commonly used in the previous studies. The results of this study are consistent with that of other studies in terms of the predictive power of Written Test (GMAT) and Graduation Score (UGPA); it is interesting to observe that Written Test is not the best predictor as it was in the previous studies.