Efficacy of infectious bronchitis virus vaccines against heterologous challenge

Twenty-four-week-old white Leghorn layers were inoculated subcutaneously with a killed Newcastle disease-infectious bronchitis (Massachusetts type) virus (MIBV) vaccine. Twenty-eight weeks after vaccination, the birds were challenged intraocularly with the Arkansas strain of infectious bronchitis virus (AIBV) to determine the effects of heterologous virus exposure on egg production, egg quality and serum antibody response of the birds. The challenged hens laid significantly (P less than 0.005) fewer eggs than the unchallenged layers. Eggs laid by the unchallenged groups weighed significantly more (P less than 0.005) than those laid by the challenged groups. Further, the internal quality (Haugh units) and shell quality of eggs laid by the AIBV-challenged hens was significantly (P less than 0.005) inferior to those from the unchallenged hens. In addition, the AIBV-challenged hens laid more soft-shell, misshapen and small eggs than the unchallenged hens. The Arkansas serum haemagglutination inhibition (AIBV-HI) titres of AIBV challenged birds increased up to four weeks after challenge. The corresponding MIBV haemagglutination-inhibition (MIBV-HI) titres decreased during the same period. The study indicates that killed MIBV vaccine offered no protection to birds exposed to heterologous AIBV.     

Effects of infectious bronchitis virus (Arkansas strain) on laying chickens

Seventy-seven-week-old white leghorn layers were inoculated intraocularly with the Arkansas strain of infectious bronchitis virus (AIBV) to study the effects of the virus on egg production and on antibody response of the birds. Infected hens laid fewer eggs than the controls, and those eggs weighed less than eggs laid by controls. Further, the shell quality and internal quality of eggs laid by infected birds were inferior. The serum hemagglutination-inhibition (HI) titers of infected birds increased continuously through 4 weeks postinfection; serum HI titers of the controls were negligible.     

Immune response to oil-emulsion vaccines with single or mixed antigens of Newcastle disease, avian influenza, and infectious bronchitis

Inactivated Newcastle disease virus (NDV), avian influenza virus (AIV), and infectious bronchitis virus (IBV) antigens were evaluated for immunological efficacy in monovalent and polyvalent vaccines. Vaccinated broilers were bled for hemagglutination-inhibition (HI) tests at 1- or 2-week intervals. Half of the chickens were challenged with the Largo isolate of velogenic viscerotropic (VV) NDV at 8 weeks post-vaccination, and the remainder were challenged with the Massachusetts 41 strain IBV at 9 weeks post-vaccination. Newcastle disease HI titers were reduced significantly (P less than 0.05) from those of monovalent control vaccine groups when IBV antigen was emulsified in mixtures with low (1-3x) concentrated NDV or NDV and AIV antigens. Avian influenza HI titers were significantly (P less than 0.05) lower than those of the control monovalent groups when highly concentrated NDV was part of the polyvalent vaccine. Infectious bronchitis HI titers were higher than those of control monovalent groups in 13 of 15 vaccine groups when IBV antigen was in polyvalent formulations. VV NDV challenge killed all non-NDV vaccinates and induced increased HI titers in NDV vaccinates but no morbidity or mortality. Sixty of 80 IBV vaccinates experienced a fourfold or greater HI titer increase following challenge. All non-IBV vaccinates seroconverted at 1 week post-challenge.     

Simulation of maternal immunity by inoculation of immune yolk preparations into the yolk sac of 1-day-old chickens.

Yolk harvested from eggs laid by hens hyperimmunized with killed Newcastle disease virus (NDV) was inoculated into the yolk sac of 1-day-old specific-pathogen-free (SPF) chickens. Serum hemagglutination-inhibition antibody titers reached maximum levels 1 to 4 days after yolk inoculation and declined at a rate similar to that reported for naturally acquired maternal antibody. Expected levels of immune interference were observed when yolk-inoculated chickens were vaccinated with a conventional oil-emulsion NDV vaccine. These results show that yolk-sac inoculation with yolk antibody is a suitable approach for producing maternally immune chickens for laboratory studies.     

Vaccination against the avian infectious bronchitis virus affects sperm concentration, sperm quality and blood testosterone concentrations in cockerels

1. It was previously found that cockerels vaccinated with live attenuated avian infectious bronchitis virus (AIBV) have decreased serum testosterone concentrations, epididymal stones and reduced fertility. The objectives of this study were twofold: to determine if reduced fertility following vaccination with live attenuated virus was the result of reduced sperm concentration or reduced sperm quality and to determine if vaccination with a killed strain of virus caused a similar reduction in sperm function in vivo. 2. Specific-pathogen-free Single Comb White Leghorn cockerels were divided into three treatment groups: no vaccination (NONVAC), vaccination with killed AIBV virus (KVAC) or vaccination with live attenuated AIBV virus (LVAC). Semen was collected daily from 17 to 27 weeks of age, and semen quality was assessed frequently by analysing sperm concentration, viability, motility, and ability to reach and interact with the ovum in vivo. Blood plasma was assayed for testosterone concentration. 3. Differences in sperm analysis among treatment groups were limited. Sperm viability was increased in NONVAC during week 20 which then decreased in week 22 when compared to vaccinated cockerels. Acrosome damage was increased in vaccinated cockerels in week 22, and decreased in weeks 25 and 27 when compared to controls, which correlate to the period of epididymal stone development. Plasma testosterone concentrations and sperm concentrations among treatment groups were different only at 16 and 19 weeks of age, respectively. There were no differences across treatment groups in sperm mobility through Accudenz or in numbers of sperm holes in perivitelline membranes of eggs following insemination with semen from 27-week-old cockerels. No differences were observed in viability or acrosome integrity between cockerels with and without epididymal stones within treatment groups. 4. In conclusion, pre-pubertal vaccination against AIBV and subsequent epididymal stone formation had a limited effect on sperm concentration, sperm quality and plasma testosterone concentrations. Vaccination with killed AIBV vaccine did not diminish effects on sperm function in vivo.     

Ornithobacterium rhinotracheale infection in turkeys: immunoprophylaxis studies

Ornithobacterium rhinotracheale has been shown to cause serious clinical illness and is a significant concern to the turkey industry because of its potential economic impact. In this study, 6-wk-old turkeys were vaccinated intranasally with a live or subcutaneously with a killed O. rhinotracheale vaccine. At 14 or 21 wk of age, the birds were challenged intratracheally with live O. rhinotracheale. Airsacculitis and pneumonia occurred less frequently in vaccinated birds than in unvaccinated birds after challenge with O. rhinotracheale. Ornithobacterium rhinotracheale was recovered from unvaccinated, challenged birds but not from vaccinated, challenged or from unchallenged birds. Thus, turkeys inoculated with live or killed O. rhinotracheale vaccine were protected from pathologic changes.     

A dot-immunobinding assay for infectious bronchitis virus

Common Whatman filter paper grade 1 and nitrocellulose membrane were compared for their sensitivity in a dot-immunobinding assay for detection of serum antibody titers to Arkansas avian infectious bronchitis virus (AIBV). For a blue to purple color detection, serum antibodies were bound to AIBV antigen adsorbed on the filter-paper discs or nitrocellulose membrane. Rabbit anti-chicken IgG horseradish-peroxidase (HRP) conjugate and hydrogen peroxide with 4-chloro-1-naphthol (HRP-color development reagent) were applied. The study indicates that very small amounts of antigen/antisera are needed for the dot-immunobinding assay. The test is sensitive, economical, and easy to run and can be completed within 6-8 hours.     

A standardized enzyme-linked immunosorbent assay for infectious bronchitis virus: comparison with hemagglutination-inhibition and virus-neutralization assays for measuring protective antibody levels in chickens

An enzyme-linked immunosorbent assay (ELISA) was developed to measure antibodies to infectious bronchitis virus (IBV) in chickens. The results are reported in IBV standard ELISA values calculated by comparing antibody levels in test sera with antibody levels in a series of standard reference sera. The IBV standard ELISA values were good indicators of responses to vaccination and the immune status of experimentally challenged birds. Although the assay was not serotype-specific, the sensitivity makes it ideally suited for determining the immune status of poultry flocks. The assay results compared favorably with other laboratory results, including virus-neutralization titers, hemagglutination-inhibition levels in sera, virus isolation from vaccinated/challenged birds, and the tracheal ring test results.     

Serological response in broiler chicks to different commercial Newcastle disease and infectious bronchitis vaccines.

Broiler chicks were administered vaccines against Newcastle disease and infectious bronchitis (both Arkansas and Massachusetts strains) at 2 weeks of age as either primary or secondary vaccinations. The vaccine was administered as a spray at 2 weeks of age to chicks that had received Newcastle disease vaccine alone, bronchitis vaccine alone, both vaccines in combination, or no vaccine at day 1 in the hatchery. The Newcastle disease hemagglutination-inhibition response was significantly lower in chicks receiving Newcastle disease vaccine as a secondary vaccine at 2 weeks than in those receiving the vaccine as a primary vaccination at that age. In contrast, the bronchitis hemagglutination-inhibition response was significantly higher in chicks receiving bronchitis vaccine as a secondary vaccination at 2 weeks than in those receiving the vaccine as a primary vaccination at that age.     

Epididymal stone formation and decreased sperm production in roosters vaccinated with a killed strain of avian infectious bronchitis virus

Our objective was to determine if vaccination with killed avian infectious bronchitis virus (AIBV) causes epididymal calcium stones in the rooster as is seen following vaccination with live attenuated AIBV. Specific-pathogen-free roosters were divided into three groups: nonvaccinated (NONVAC), live attenuated AIBV-vaccinated (LVAC), and killed AIBV-vaccinated (KVAC) groups. Roosters were vaccinated at 2, 6, 10, and 14 wk of age and the epididymal region was observed at 27 wk of age. Epididymal stones were present in 13% of NONVAC, 50% of KVAC, and 64% of LVAC roosters. Histologically, immune cells were seen in the interstitium of efferent ductules containing stones. We conclude that use of a killed vaccine does not reduce the incidence of epididymal stones.     

Pathogenicity and distribution of egg-drop syndrome-1976 virus (JPA-1) in inoculated laying hens

Rhode Island Red laying hens that lacked hemagglutination-inhibition antibody were inoculated orally with the JPA-1 strain of adenovirus isolated from a flock affected with egg-drop syndrome-1976 in Japan and observed for 80 days. Inoculated hens laid abnormal eggs, such as shell-less, soft-shelled, and cracked eggs and those with loss of pigmentation, from 8 days postinoculation (PI). Fifteen out of 16 hens laid abnormal eggs. Egg-production rte fell from 94% to 50% between 13 and 16 days PI. When the abnormal eggs were excluded, egg production was 17%; then it recoverd slowly, reaching 67% by the end of the experiment. The virus was recovered from various organs of inoculated hens from 3 to 7 days PI. Fluorescent antigens of the virus were observed in the epithelial cells and desquamated cells from the epithelium of the uterus and isthmus 10 and 14 days PI.     

Evaluation of the effectiveness of two infectious bronchitis virus vaccine programs for preventing disease caused by a California IBV field isolate

Infectious bronchitis virus CA99 serotype was isolated from several broiler flocks in Northern California. The virus caused late-onset respiratory disease and increased airsacculitis condemnation in affected flocks despite the use of an established infectious bronchitis virus vaccination program. An experimental study compared Holland/Arkansas and Massachusetts/Arkansas vaccination protocols to determine the efficacy of commercial infectious bronchitis virus vaccines in reducing respiratory disease and airsacculitis lesions found at processing that were associated with a CA99 field isolate. All vaccination groups were given Massachusetts/Connecticut strains of infectious bronchitis virus vaccines at age 1 day followed by vaccination with either Holland/ Arkansas or Massachusetts/Arkansas vaccine strains at 18 days of age. Birds were challenged at age 31 days with a CA99 field isolate. Gross pathology, histopathology, and virus isolation were evaluated. Chickens vaccinated with Holland/Arkansas had marginally better protection against CA99 challenge than chickens vaccinated with Massachusetts/Arkansas, although differences were not statistically significant.     

Effects of an Arkansas strain of infectious bronchitis vaccine on the head-associated lymphoid tissue (HALT).

Chicks were vaccinated with an Arkansas strain of infectious bronchitis virus (IBV) vaccine when they were 1 day (Trial 1) or 4 weeks old (Trial 2). Starting at 4 weeks 3 days of age, chicks in both trials were subjected to an assay that measures the immunofunctional response of the gland of Harder (GH), one of the components of the head-associated lymphoid tissue (HALT). The assay involved multiple ocular exposures to killed Brucella abortus antigen, after which tears were collected and titered for antibodies to B. abortus. Following this, select tissues from vaccinated and unvaccinated chicks were collected and examined microscopically for specific lesions. Both functional and structural alterations were detected in the HALT of IBV-vaccinated chicks. Antibody titers to B. abortus in vaccinated chicks were significantly lower (P less than 0.05) than in unvaccinated controls. Structurally, there were elevations (P less than 0.01) in the number of lymphoid cells and follicles found in the mucosal lining of the nasal cavity. This occurred in the vaccinated chicks of both trials. Otherwise, histologic changes were confined to the chicks vaccinated at 4 weeks of age (Trial 2). In that trial, there were elevations in lymphoid-cell and follicle numbers in the eyelid (P less than 0.01) and lacrimal gland (P less than 0.05).     

Diagnostic utility of egg yolk for the detection of avian metapneumovirus antibodies in laying hens

Surveillance and diagnosis of avian metapneumovirus (AMPV) infection typically involve measurement of serum antibodies. In the current study, eggs instead of serum samples were used for the detection of AMPV antibodies in egg-laying chicken hens by enzyme-linked immunosorbent assay (ELISA). AMPV-free commercial layer hens were experimentally challenged with AMPV strain SC1509 through intravenous or oculonasal administration. Antibody levels were determined by ELISA. AMPV antibodies were detected in egg yolks from challenged hens by 7 days postinoculation (dpi), with the peak titer at 16 dpi. Antibody levels in eggs laid at 28 dpi correlated well (r = 0.93) with sera taken 28 dpi from the same hens. In a field trial of the yolk ELISA, six broiler breeder farms were surveyed, and all tested positive for AMPV antibodies in hen eggs, although positivity varied from farm to farm. Abnormal discolored eggs collected from outbreak farms had significantly higher titers of AMPV yolk antibodies than normal eggs from the same farm, unlike clinically healthy farms, where normal and abnormal eggs had similar antibody titers. These results indicate that diagnosis of AMPV infection by yolk ELISA to detect anti-AMPV antibodies may be a suitable alternative to serologic testing.     

Studies of infectious laryngotracheitis vaccines: immunity in broilers

Broiler chickens were vaccinated at 18 days of age against infectious laryngotracheitis (ILT) using chicken-embryo-origin (CEO) and tissue-culture-origin (TCO) vaccines, each vaccine given either by drinking water, spray, or eyedrop. Controls were not vaccinated. The broilers were challenged 3 weeks later with virulent ILT virus (USDA challenge strain). Serum samples taken before challenge were analyzed by a virus neutralization (VN) test to determine titers due to vaccination. Both vaccines, regardless of route of administration, produced low VN titers, geometric mean titer (GMT) being less than 4.0 in all vaccinated groups. When administered by the same route, the CEO vaccine produced higher titers than the TCO vaccine. Titers following drinking-water or eyedrop administration of vaccines were higher than titers following spray vaccination. There was an inverse relationship between pre-challenge VN titers of groups of birds and the percentage of birds in the groups dying from ILT virus challenge. The drinking-water route of vaccination provided the most protection, while the spray provided the least.     

Fowl cholera immunity induced by various vaccines in broiler minibreeder chickens determined by enzyme-linked immunosorbent assay

Broiler minibreeder hens were vaccinated for protection against fowl cholera at 12 and 21 weeks of age using several vaccination schemes, which included a live Pasteurella multocida (CU strain) vaccine, two commercial polyvalent fowl cholera oil-based bacterins, and two experimentally prepared polyvalent oil-based bacterins. Some treatment groups received only live or killed vaccines, whereas others received a live vaccine at 12 weeks followed by a killed product at 21 weeks. At 42 weeks of age, all birds that received the live CU vaccine twice or once followed by a bacterin survived challenge. Birds that received killed vaccines only were significantly less protected but still showed a respectable survival rate of 86%. All unvaccinated controls died within 72 hr after challenge. At 72 weeks of age, overall protection was lower than that at 42 weeks, regardless of vaccination treatment. Antibody titers were usually higher in birds that received bacterins than in those receiving live vaccines, yet overall protection was still greater in those birds that received the live cholera vaccine twice.     

Serological profiles of commercial broiler breeders and their progeny. 1. Infectious bronchitis virus

Serum samples were collected from broiler breeders and their 1-day-old, 2-week-old, and 5-week-old progeny from different regions of the United States. Individual samples were tested by hemagglutination-inhibition (HI) against six infectious bronchitis virus (IBV) strains: Massachusetts 41 (Mass), H52, Connecticut 46 (Conn), Arkansas 99, SE17, and JMK. The use of multiple strains to test broiler flocks resulted in the detection of seroconversions to Conn and JMK vaccination that were not detected with the IBV Mass HI test. Further, HI titers were detected to IBV strains not used for flock vaccination. In some cases, those titers could be due to cross reactions to antigens common to each of the virus strains. In two breeder flocks, the highest HI titers were to heterologous strains.     

Efficacy in turkeys of spray vaccination with a temperature-sensitive mutant of Bordetella avium (Art Vax)

Broad-breasted white turkeys were vaccinated with a temperature-sensitive mutant of Bordetella avium (Art Vax) at 2 and 15 days of age and challenged at 22 days of age by contact with infected birds. Necropsy was performed at 35 days of age. Two vaccination protocols (eyedrop/oral and spray cabinet/spray bottle) and two challenge isolates (Arkansas 105 and North Carolina [NC] isolates) were used. Neither the spray nor the eyedrop/oral methods of vaccination prevented infection of the anterior trachea with either of the virulent challenge strains. The spray and eyedrop/oral methods of vaccination were equally effective in reducing the severity of gross lesions in the trachea. The vaccine reduced the severity of gross lesions in the tracheas of turkeys challenged with the NC isolate to a level approximately equal to that observed in unchallenged vaccinated controls, but the vaccine only moderately reduced the severity of lesions in birds challenged with the 105 isolate.     

Pathogenicity of two strains of Mycoplasma gallisepticum in broilers

Strains F and R of Mycoplasma gallisepticum (MG) were compared in two laboratory trials for their relative pathogenicity in terms of inducing airsacculitis and antibody production to MG. Chickens exposed to the R strain had significantly higher incidence of air-sac lesions (P less than 0.05) and greater severity of airsacculitis than did chicks exposed to the F strain. In both trials, chickens vaccinated simultaneously with Newcastle disease-infectious bronchitis vaccine and exposed to MG had more severe lesions than did chickens exposed to mycoplasma alone. chickens exposed to the F strain had significantly lower geometric mean hemagglutination-inhibition antibody titers to MG than did chicks exposed to the R strain. Chickens vaccinated simultaneously with Newcastle disease-infectious bronchitis vaccine and exposed to R strain had significantly lower body weights than did chickens in the other group.     

Vaccination against infectious bronchitis in young chickens--carriers or not of maternal antibodies

The immunity to infectious bronchitis afforded by spray vaccination of mycoplasma free two days-old broilers with maternal antibodies to infectious bronchitis virus was tested by comparing zootechnical scores, clinical signs, macroscopical and microscopical changes, frequency of infectious bronchitis virus isolation following challenge at one, three and five weeks of age in vaccinated, unvaccinated, challenged and unchallenged birds. This vaccination gave a very good protection to infectious bronchitis for the most part of broiler economical life; growth delays were especially avoided. However, vaccinated and unvaccinated one-week-old birds were not protected enough. No correlation was observed between haemagglutinating antibodies titres and protection. At last this vaccination caused a notable reaction in specific pathogen free control birds of the same age.