Biomedical subjects

J Gelb

Publications and source records attributed to J Gelb.

34 records · Page 2Linked to original sources

PubMedDate not supplied

Variant serotypes of infectious bronchitis virus isolated from commercial layer and broiler chickens.

Twenty infectious bronchitis virus (IBV) field isolates obtained from commercial layer and broiler chickens in 1987 and 1988 were serotyped using the virus-neutralization (VN) test. Six different previously unrecognized variant serotypes were identified from a total of seven isolates from layer chickens. Only two isolates, both from Maine, were the same variant serotype. Variant serotypes also were recovered from layer flocks in Illinois and Washington and the province of Ontario, Canada. Two different variants were isolated from the same multi-age layer complex in Connecticut. Only one of 13 broiler chicken isolates was found to be a new variant serotype, that being from birds reared in Delaware. Cross-protection studies in specific-pathogen-free chickens indicated that vaccines containing the Holland, L-1, or Connaught strains of Massachusetts (Mass) combined with Arkansas produced a broader spectrum of immunity against challenge with the layer variants than Mass (Holland) alone or Mass (L-1) + Connecticut. All vaccines tested produced solid immunity (greater than or equal to 80% protection) against the broiler variant virus.

Animals↗

PubMedDate not supplied

Response to several avian respiratory viruses as affected by infectious bursal disease virus.

After being inoculated with the infectious bursal disease virus (IBDV) at one day of age, specific-pathogen-free chickens were inoculated with either Newcastle disease virus (NDV), infectious bronchitis virus (IBV), or infectious laryngotracheitis virus (ILTV). Their immunity was challenged 2-3 weeks later with homologous virus, and antibody titers were determined for ILTV and IBV. Several studies were made to determine the effects of IBDV on the development of persistent or chronic virus infections. Chickens susceptible to IBDV were exposed to IBDV at one day and inoculated at two weeks of age with either NDV, IBV, or ILTV. Two, three, four, and five weeks postinoculation with the respiratory viruses, tracheal swabbings were collected for virus isolations. The birds were challenged with homologous virus at five weeks postinoculation. The results show that early (1-day) infections with IBDV affect the response of young birds to several avian respiratory viruses, as indicated by lowered resistance to challenge and humoral antibody levels for birds inoculated with ILTV and NDV. Birds infected with IBV and IBDV withstood IBV challenge but were much more prone to persistent infections than were birds not exposed to IBDV. High death rates and decreased weights in all IBDV-inoculated groups demonstrated the damaging effects of early IBDV infection.

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PubMedDate not supplied

Comparisons of the genomic RNA of Arkansas DPI embryonic passages 10 and 100, Australian T, and Massachusetts 41 strains of infectious bronchitis virus.

The genomic ribonucleic acid (RNA) of Arkansas DPI at embryonic passages 10 and 100, Australian T, and Massachusetts 41 strains of infectious bronchitis virus (IBV) were compared using two-dimensional, 32PpCp-labeled oligonucleotide fingerprinting. The Arkansas DPI strain embryonic passage 10 was pathogenic for chickens and had one oligonucleotide not present in the attenuated passage 100. The remaining Arkansas DPI oligonucleotides had identical electrophoretic mobility. The fingerprint patterns of the Australian T, Massachusetts 41, and Arkansas DPI IBV genomes were dissimilar, thus indicating they were genetically distinct. The distinctive fingerprint patterns of these virus strains, all identified as IBV by other criteria, indicate considerable genomic variation. Fingerprinting is reliable and sensitive, and should be used in combination with other characterization methods for identifying and differentiating IBV strains.

Animals↗

PubMedDate not supplied

Studies on interferon induction by infectious bursal disease virus (IBDV). II. Interferon production in White Leghorn chickens infected with an attenuated or pathogenic isolant of IBDV.

Infectious bursal disease virus (IBDV) isolants that differed in virulence for chickens, were compared as to: 1) induction of interferon in serum and tissues; and 2) stimulation of IBDV serum antibody. Specific-pathogen-free chickens were infected at one day and four weeks of age by the subcutaneous and intranasal routes of inoculation. The pathogenic isolant induced a more generalized interferon response than the attenuated isolant, independent of age or route of inoculation. Pathogenic IBDV stimulated interferon in serum, kidney, lung, thymus, spleen, and bursa of Fabricius. The attenuated virus induced interferon only in the bursa. The serum interferon response was greater following inoculation with pathogenic IBDV than with the attenuated virus. Serum interferon titers peaked 2-3 1/2 days after inoculation. The pathogenic and attenuated viruses stimulated similar IBDV-neutralizing antibody responses, which occurred after peak serum interferon activity.

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PubMedDate not supplied

Protection afforded infectious bronchitis virus-vaccinated sentinel chickens raised in a commercial environment.

The protective efficacy of three infectious bronchitis virus (IBV) vaccines for sentinel chickens raised with commercial Delmarva broiler chickens was evaluated during winter 1987. Specific-pathogen-free leghorn sentinel chickens were vaccinated with Massachusetts (Mass) alone, Mass and JMK, or Mass and Arkansas (Ark) combination live vaccines, or they remained unvaccinated. Four weeks post-vaccination, sentinels were placed on broiler farms at weekly intervals for 3 weeks corresponding to weeks 4, 5, and 6 of the broiler growing cycle. Vaccine efficacy was evaluated based on IBV reisolation attempts from tracheal swabbings following a 1-week field exposure period. Sentinel chickens vaccinated with Mass and Ark combination vaccine were best protected against IBV field challenge. Only four IBV isolations were made out of a 3-week total of 36 attempts, for an 11% isolation rate. IBV vaccines containing either Mass alone or Mass and JMK offered much lower levels of protection.

Animal Husbandry↗

PubMedDate not supplied

Serum antibody responses of chickens following sequential inoculations with different infectious bronchitis virus serotypes.

Sequential inoculations of chickens with different live infectious bronchitis virus (IBV) antigenic types had major effects on virus-neutralization (VN) and hemagglutination-inhibition (HI) serum antibody responses. Antibody production in IBV-inoculated chickens that were reinoculated 8 weeks later with heterologous virus was largely directed against the virus used for initial inoculation rather than the virus used for reinoculation. In addition, chickens inoculated sequentially with IBV produced a broadened spectrum of serum antibodies that reacted with IBV types to which the birds had never been exposed (JMK and Florida). Chickens inoculated sequentially with heterologous IBV tended to produce higher levels of cross-reacting antibody than birds given homologous virus inoculations. Levels of cross-reacting antibodies were lower than levels of specific antibodies directed against viruses that the birds had received. Limited studies indicated that birds with cross-reacting antibodies were not protected against challenge with the virus that the cross-reacting antibody was directed against. Implications of the research for interpreting serological data from commercial chicken flocks are discussed.

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PubMedDate not supplied

Pathogenicity and cross-protection of pigeon paramyxovirus-1 and Newcastle disease virus in young chickens.

Avian paramyxovirus-1 (PMV-1) isolates from Delaware racing pigeons were compared with Newcastle disease virus (NDV) in pathogenicity and cross-protection studies in young chickens. The pathogenicity of pigeon PMV-1 isolates was more closely related to mesogenic (Roakin) NDV than to lentogenic (La Sota) or velogenic (Texas GB) NDV strains. Pigeon PMV-1 produced 100% mortality in 1-day-old NDV-susceptible chickens following intratracheal and intracerebral inoculation. Laboratory tests often used in conjunction with chicken pathogenicity procedures for patho-typing NDV gave conflicting results. Pigeon PMV-1 isolates produced large clear plaques (up to 3.5 mm) in chicken-embryo-fibroblast cultures. Chicken embryo mean death times were considerably greater for pigeon PMV-1 (88 and 109 hr) than for Roakin (66 hr) and Texas GB (48 hr). B1 strain NDV and pigeon PMV-1 produced complete cross-protection in challenge studies in chickens. Extensive cross-reaction between pigeon PMV-1 and NDV occurred in hemagglutination-inhibition tests using polyclonal antisera. However, pigeon PMV-1 and NDV were readily distinguishable using a NDV monoclonal antibody, 2F12.

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PubMedDate not supplied

Serologic and cross-protection studies with several infectious bronchitis virus isolates from Delmarva-reared broiler chickens.

Five isolates, from broiler-type chickens, capable of causing acute respiratory disease were identified as infectious bronchitis virus (IBV). The agar-gel precipitin (AGP) test was effective in identifying the isolates as IBV. Virus-neutralization (VN) and cross-challenge tests indicated two of the isolates to be Massachusetts types and one to be a JMK type. The remaining isolates were different from strains normally encountered in chickens reared on the Delmarva Peninsula. One isolate, although serologically similar to the Connecticut strain, was able to infect Connecticut-virus-immune chickens. Another isolate was similar to Arkansas 99, a strain not previously reported in Delmarva.

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PubMedDate not supplied

Prevalence of Arkansas-type infectious bronchitis virus in Delmarva peninsula chickens.

The prevalence of Arkansas (Ark)-type infectious bronchitis virus (IBV) in Delmarva peninsula broiler-type chickens was determined. The immunity of 5-to-11-week-old commercial broilers was evaluated by intraocular inoculation with Ark-type DPI strain (Ark DPI) challenge virus and collection of tracheal swabbings 5 days later. Serum Ark-type antibody titers were obtained using the virus-neutralization test. Eighty-five flocks were tested from January to August 1981. Nearly 60% of the flocks had substantial (greater than or equal to 70%) local immunity of the upper respiratory tract. Twenty-two percent had intermediate (50-69%) and 19% of the flocks had low (less than or equal to 40%) levels of local immunity. Serum antibody titers generally agreed with challenge results. In addition, high Ark-type IBV neutralizing-antibody titers were found in 16 Delmarva broiler breeder flocks. Seven current IBV field isolates were characterized for antigenic similarity to Ark DPI. Four isolates contained Ark antigen(s) based on significant neutralization in virus-neutralization tests and on substantial immunity to challenge afforded by Ark DPI virus immunization. Three isolates did not appear to contain Ark antigen(s). Immunization of chickens with Ark DPI virus afforded substantial protection against Connecticut- and homologous-type virus challenge, partial immunity (63%) against JMK, and no protection against the Massachusetts 41 strain of IBV.

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PubMedDate not supplied

Effect of serial embryo passage of an Arkansas-type avian infectious bronchitis virus isolate on clinical response, virus recovery, and immunity.

Infectious bronchitis virus (IBV) Arkansas-type DPI strain (Ark DPI) was attenuated by serial passage in chicken embryos. Virus of passage 50 was less pathogenic for day-old maternally immune broiler-type chickens than virus of passage 10 or 25 as determined by clinical response to vaccination, virus isolation in respiratory (trachea) and nonrespiratory (kidney and cloaca) tissues, and weight-gain studies. Chickens vaccinated with virus of passage 10, 25, or 50 were at least 80% resistant to homologous virus challenge of the upper respiratory tract 4 and 6 weeks postvaccination. Serum antibody production by passage-50-vaccinated chickens was comparatively low at 4 weeks but at 6 weeks was similar to that in chickens vaccinated with virus of passage 10 or 25.

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Differentiation of infectious bronchitis virus serotypes using polymerase chain reaction and restriction fragment length polymorphism analysis.

Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis were used to differentiate between serotypes of several infectious bronchitis virus (IBV) strains. A sequence of 1720 base pairs (bp) that contains the S1 glycoprotein gene of IBV was amplified by PCR, purified, and digested with restriction enzymes. Eleven reference IBV strains were grouped according to the RFLP patterns. The IBV Holte, Arkansas DPI, SE 17, Md 27, and Iowa 97 strains could be differentiated from the other IBV strains using the restriction enzyme HaeIII. The Beaudette, Massachusetts 41, Connecticut, and Florida 88 strains had the same HaeIII RFLP pattern but could be differentiated using XcmI and BstYI restriction enzymes. The Gray and JMK strains could not be differentiated by their RFLP patterns following digestion with 23 different restriction enzymes. Twenty-six samples (field isolates and reference strains) of IBV, previously serotypes by the virus-neutralization (VN) test in embryonating eggs, were analyzed in a blind fashion. The results using the PCR and RFLP analysis agreed with the serotype for traditional and variant IBV viruses as determined by the VN test.

Base Sequence↗

PubMedDate not supplied

Efficacy in chickens of a herpesvirus of turkeys recombinant vaccine containing the fusion gene of Newcastle disease virus: onset of protection and effect of maternal antibodies.

The onset of protection against Newcastle disease and the effect of maternal antibodies to Newcastle disease virus (NDV) and Marek's disease virus (MDV) on vaccine efficacy were determined following vaccination of chickens with a recombinant herpesvirus of turkeys (HVT) vaccine expressing the fusion (F) glycoprotein gene of NDV. Onset of protection following intra-abdominal administration of the recombinant HVT/F vaccine at 1 day of age and subsequent ocular challenge with the neurotropic velogenic Texas GB strain of NDV was determined to occur between days 14 and 21 post-vaccination (PV). Vaccination with the Hitchner B1 strain of NDV resulted in protection by day 6 PV, and vaccination with an inactivated NDV oil-emulsion vaccine induced protection by day 14 PV. One-day-old broiler-type chickens with maternal antibodies to both NDV and MDV and 1-day-old specific-pathogen-free (SPF) white leghorn chickens lacking maternal antibodies were vaccinated with the recombinant HVT/F vaccine or with control vaccines, challenged intra-abdominally with the very virulent RB1B strain of MDV on day 8 PV, and challenged with the Texas GB strain of NDV on day 29 PV. The HVT/F and NDV strain Hitchner B1 vaccines provided 73% and 80% protection, respectively, against NDV in broilers, whereas both vaccines resulted in 100% protection in SPF leghorns.

Animals↗

PubMedDate not supplied

Attenuation of lentogenic Newcastle disease virus strain B-1 by cold adaptation.

The Hitchner B-1 strain of Newcastle disease virus was plaque-cloned and then serially passaged 36 times in specific-pathogen-free (SPF) chicken embryos incubated at two different temperatures. Virus passaged at a reduced temperature (29 C) was identified as cold-adapted (Ca) and virus passaged at the normal temperature (37 C) was designated non-cold-adapted (non-Ca). The Ca and non-Ca B-1 viruses were compared with the parent B-1 and a commercial B-1 vaccine. In vitro Ca B-1 characteristics included adaptation for more rapid growth at 29 C and the aquisition of temperature sensitivity indicated by substantially reduced growth at 41 C, properties not seen with non-Ca B-1. Embryo mean death times for the Ca virus (140 hr) were longer than for non-Ca B-1 (107 hr) and parent B-1 (121 hr) viruses. The Ca virus retained a rapid (< 2 hr) hemagglutination (HA) elution rate but lost the property of binding the monoclonal antibody AVS-I typical of other B-1 strains. The pathogenicity of the Ca B-1 strain was compared to the non-Ca B-1, parent B-1 strain, and a commercial B-1 strain vaccine in 1-day-old broiler-type chickens. Pathogenicity was evaluated by assessing the severity of respiratory disease signs and the incidence of airsacculitis, perihepatitis, and pericarditis lesions in inoculated chicks. A respiratory disease index was calculated for each B-1 strain based on daily observation scores that determined the presence or absence of disease signs (coughing, rales, labored breathing, death) from 1 to 14 days following intratracheal inoculation with 10(6) 50% egg infective doses of virus per chick. The lower respiratory disease index obtained for the Ca B-1 strain (0.075) indicated it was less pathogenic than the commercial B-1 vaccine (0.296) and the non-Ca (0.478) and parent (0.521) B-1 strains. Ca B-1-infected chicks had only a 5% incidence of air sac lesions, compared to chicks given non-Ca (65%), Hitchner B-1 (65%), or a commercial B-1 vaccine (30%). Immunogenicity tests performed in 1-week-old SPF leghorn chickens demonstrated that Ca B-1 induced complete protection when administered intraocularly as a single entity. However, when Ca B-1 was given in combination with a modified live infectious bronchitis virus vaccine, chickens were only partially protected (60-75%) against Texas GB strain-induced neurotropic velogenic Newcastle disease.

Animals↗

PubMedDate not supplied

Antigenic and S-1 genomic characterization of the Delaware variant serotype of infectious bronchitis virus.

A previously unrecognized infectious bronchitis virus (IBV) serotype, referred to hereafter as the Delaware variant (DE var), was isolated from commercial broiler chickens during a severe, widespread respiratory disease epornitic in the Delmarva peninsula region of the United States in January-March 1992. The DE var serotype was found to be antigenically unrelated by virus-neutralization (VN) test to nine reference IBV serotypes from North America. Additional VN tests indicated that the DE var isolates (DE/072/92, DE/121/ 92, DE/152/92, and DE/174/92) from broilers were fully or partially neutralized by monospecific antisera prepared against themselves and against two IBV field isolates (DE/492/90 and DE/903/90) recovered from a Delmarva commercial layer flock experiencing egg production losses in 1990. Antigenic relatedness values determined by VN indicated layer isolate DE/492/90 was more closely related to the broiler DE var isolates than was layer isolate DE/903/90. Cross-challenge tests performed in specific-pathogen-free chickens also demonstrated the antigenic similarity of the broiler (DE/072/92 and DE/174/92) and the layer isolates (DE/492/90 and DE/903/90), with heterologous strain protection values ranging from 55% to 100%. Protection values of DE var isolates vs. Massachusetts 41 and Arkansas DPI were considerably lower (0-60%). The S-1 gene of the US/DE/072/92 isolate of the DE var serotype was amplified by reverse transcription polymerase chain reaction, cloned, and sequenced. The DE var S-1 gene sequence was compared with the S-1 gene sequences of IBV serotypes from North America, Europe, and Australia. A dendrogram based on this analysis supported the conclusion that the DE var serotype is highly novel among IBV. A high degree of similarity (> 88%) was observed between the S-1 genes of the DE var broiler isolates (DE/072/92 and DE/174/92) and layer isolates (DE/492/90 and DE/903/90). These data, taken with the VN and cross-challenge results, establish a genetic as well as an antigenic link between the isolates from layers and broilers and indicate the DE var serotype was responsible for both infectious bronchitis outbreaks.

Animals↗

PubMedDate not supplied

Serotype identification of avian infectious bronchitis virus by RT-PCR of the peplomer (S-1) gene.

The S-1 peplomer gene sequences of 31 strains of avian coronavirus infectious bronchitis virus (IBV) from North America, Europe, and Australia were compared to identify common and unique regions for possible diagnostic applications. S-1 sequences that were conserved among serotypes and sequences that were variable between serotypes were identified. Based on conserved S-1 gene sequences, "general" degenerate oligonucleotide primers were designed that amplified IBV genomic RNA by the reverse transcriptase polymerase chain reaction (RT-PCR) procedure regardless of serotype. Primers specific for IBV serotypes Massachusetts, Connecticut, Arkansas, JMK, Delaware (DE/072/92), and California (CA/633/85) were designed from regions of the S-1 gene exhibiting extensive sequence hypervariability. The ability to identify these six serotypes of IBV by RT-PCR was demonstrated by testing the serotype-specific primers on a panel of unknown samples that included 30 reference strains and field isolates previously characterized by virus neutralization (VN). The use of serotype-specific primers in RT-PCR provides a rapid and accurate means of identifying IBV.

Amino Acid Sequence↗

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Infectious bronchitis virus antibodies in tears and their relationship to immunity.

Antibodies to infectious bronchitis virus (IBV) in chicken tears were investigated to determine if they could be used as an indicator of protective immunity. Antibody production in tears and serum was measured by enzyme-linked immunosorbent assay (ELISA) in specific-pathogen-free (SPF) white leghorn and broiler chickens vaccinated with a live attenuated vaccine containing the Massachusetts (Mass) Connaught strain of IBV. The effect of virulent infectious bursal disease virus (IBDV) infection on antibody production in tears was also evaluated. Immunity was assessed by challenging the chickens with Mass 41 and performing tracheal swabbings 5 days later. In addition, tears were also evaluated for virus-neutralizing (VN) antibodies to IBV. Following eyedrop vaccination, anti-IBV antibodies were consistently detected by ELISA in tears prior to and in higher concentrations than in the sera of SPF white leghorn and broiler chickens. Maternal IBV antibodies were present in the tear secretions of broiler chickens but in lower concentrations than in sera. Infection of SPF chicks with a virulent and immunosuppressive strain of IBDV at 1 day of age greatly reduced IBV ELISA antibody production in tears as well as serum compared with infection of chickens with IBDV at 14 days of age. IBV ELISA and VN antibody levels in tears were not accurate indicators of IBV immunity as determined by challenge with Mass 41. High tear IBV antibody titers were observed in some chickens determined to be susceptible to IBV challenge and low tear titers were detected in some protected chickens. This finding suggests that mechanisms other than antibody-mediated immunity in tears are important in viral clearance following challenge.

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