Vaccination of chickens against a Belgian nephropathogenic strain of infectious bronchitis virus B1648 using attenuated homologous and heterologous strains

White Leghorn chicks without and with maternally derived antibodies (MDA) to infectious bronchitis virus (IBV) and broiler chicks with MDA were vaccinated at 1 day of age either with H120 vaccine, combined H120 and D274 vaccines or with a non-commercial attenuated strain derived from the virulent Belgian nephropathogenic IBV strain, B1648. Protection following challenge with virulent B1648 was assessed 4 weeks later by virus isolation from the trachea, antigen detection in the kidney by immunofluorescence and mortality rates. Vaccination with either homologous or heterologous vaccines reduced the duration of virus replication in the trachea of all groups compared to unvaccinated controls. Homologous vaccination reduced the incidence of virus replication in the kidney. Heterologous vaccination (H120 to D274) did not reduce kidney infection in the MDA + groups; however, partial kidney-protection was found in the MDA - group. There was no correlation between serum antibody titres measured by ELISA and the degree of kidney protection.     

Emergence of a nephropathogenic avian infectious bronchitis virus with a novel genotype in India

We describe the emergence of a nephropathogenic avian infectious bronchitis virus (IBV) with a novel genotype in India. The Indian IBV isolate exhibited a relatively high degree of sequence divergence with reference strains. The highest homology was observed with strain 6/82 (68%) and the least homology with strain Mex/1765/99 (34.3%).     

Increased level of protection of respiratory tract and kidney by combining different infectious bronchitis virus vaccines against challenge with nephropathogenic Brazilian genotype subcluster 4 strains

Genotyping of seven infectious bronchitis virus (IBV) strains isolated in Brazil showed that all belonged to the common Brazilian genotype and that these strains were closest to the subcluster of strain IBV/Brazil/2007/USP-19. Pathotyping of four selected Brazilian strains showed that they all caused a considerable level of ciliostasis in the trachea but at a somewhat lower level than did M41 and Brazilian strains 50/96, 57/96, 62/96 and 64/96 representing four different serotypes that had been reported earlier. In contrast to the M41 challenge strain, all Brazilian isolates replicated in kidney tissue in a high percentage of non-vaccinated challenged birds, clearly showing that they are nephropathogenic. As for the tracheal protection, the results using Massachusetts (Mass) vaccination against the recent strains seemed to show protection higher on average than for the strains reported earlier. A single or twofold vaccination with a Mass vaccine resulted in a mean tracheal protection level against the four challenge strains of 92% and 90%, respectively, whereas a single and twofold vaccination with a Mass vaccine halved the percentage of infected kidneys (14% and 13%, respectively, P?P?相似文献   

Pathogenicity of Australian strains of avian infectious bronchitis virus

The pathogenicity of 25 strains of infectious bronchitis virus (IBV) isolated in Australia between 1961 and 1994 was compared in white leghorn specific pathogen-free chicks. Twelve strains were nephropathogenic and 10 respiratory, the other three being of mixed pathogenicity. The IBV strains identified as nephropathogenic induced clinical nephritis, gross and histological kidney lesions, and mortality of 5-90%. According to the severity of these features, the nephropathogenic strains could be further subdivided into strains of high, moderate or low pathogenicity. The three strains of mixed pathogenicity induced tracheitis, mild clinical nephritis and kidney lesions but no mortality. The 10 respiratory strains caused histological lesions in the trachea but not in the kidney, and did not induce clinical nephritis or mortality. Of 12 IBV strains isolated between 1961 and 1976, nine were nephropathogenic, inducing mortality of 15-90%. In contrast, of 13 strains isolated between 1981 and 1994, only three were nephropathogenic, inducing mortality of 5-37%, whereas nine were respiratory. Seven of these nine strains, unlike other respiratory strains, failed completely to replicate in the kidney. The results indicated a change in the prevalent IBV strains from highly nephropathogenic (1960s to 1970s) to respiratory (1980s to early 1990s); moreover, the late 1980s saw the emergence of respiratory strains with altered tissue tropism.     

Sequence of the spike protein of the Belgian B164S isolate of nephropathogenic infectious bronchitis virus

The sequence of the gene encoding the spike glycoprotein (S) of the 1984 Belgian nephropathogenic isolate B1648 has been determined and shown to encode a protein of 1171 amino acids. Comparison of the deduced amino acid sequence of the S1 (amino-terminal half) of S, which induces virus-neutralizing antibodies, with that of vaccinal strains D274, H120 and D1466 revealed that it differed from them by 21, 25 and 49%, respectively, and by 24 to 25% from the North American nephropathogenic isolates Gray and Holte. The deduced amino add sequence of the S2 (carboxy-terminal) half of S differed by 10 to 12% (25% from D1466).     

Antigenic variation in strains of avian infectious bronchitis virus

Summary Fifteen british field strains of IBV were compared using cross serum neutralization tests in embryonated eggs with seven standard reference strains of IBV. While the British field strains were considered to form a relatively homogeneous group considerable antigenic variation did occur. It was considered that it was not feasible at this time to describe accurately a serotype classification for IBV, similar to that described for other virus groups.     

Serological relationship among ten strains of avian infectious bronchitis virus

Ten strains of avian infectious bronchitis virus (IBV) were studied serologically by cross-neutralization test using rabbit and chicken immune sera. With the chicken sera all 10 IBV strains were antigenically related. In particular, anti-KH serum neutralized all heterologous strains except of the Ishida strain; Nerima strain was neutralized by all antisera except of anti-Ishida serum. Most cross-reactions were less or more heterologous, thus all 10 IBV strains seemed to belong to one serological type. Using rabbit sera, all strains except of Connecticut A-5968, cross-reacted with certain other strains. Most cross-reactions were partially heterologous showing one-way-relationship; heterologous relations were observed less frequently than with chicken sera.     

Genetic grouping for the isolates of avian infectious bronchitis virus in Taiwan

Summary In order to differentiate recent isolates of avian infectious bronchitis virus (IBV) in Taiwan, polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and direct sequencing methods were used to type 25 IBV Taiwan isolates. Two conserved sequences that flank the hypervariable region I (HVR I) in the N-terminus of S1 protein gene were chosen as primers. Sequences of 228–231 base pairs (bp) were amplified by PCR from 25 Taiwan isolates and 4 reference strains (H120, Conn, JMK, Holte). PCR products were digested with 5 restriction endonucleases,BsoFI,DdeI,MboII,AluI,RsaI, and different IBV isolates were grouped according to their RFLP patterns. The RFLP patterns of the 4 reference strains in this study matched the published sequences in GenBank. Except 1 vaccine strain, the other 24 Taiwan isolates were different from these 4 and 18 other IBV strains whose sequences were published. The data from PCR-RFLP and sequencing of IBV genomes showed that the 24 Taiwan isolates can be divided into 2 distinct groups, I and II. Seven RFLP patterns are identified in group I and only 1 in group II.     

Phylogenetic analysis of avian infectious bronchitis virus strains isolated in Japan

Summary To define the origin and evolution of recent avian infectious bronchitis virus (IBV) in Japan, a genetic analysis was performed. By phylogenetic analysis based on the S1 gene including the sequence of the hypervariable regions, IBV isolates in Japan were classified into five genetic groups, which included two already-known groups (Mass and Gray). Among them, three major genetic groups were associated with the recent outbreaks of IB in Japan. One group is indigenous to Japan and could not be placed within the known existing groups in other countries. The remaining two groups, which have emerged recently, are related to isolates in China and Taiwan.     

Susceptibility of three genetic lines of chicks to infection with a nephropathogenic T strain of avian infectious bronchitis virus

Mortality rates were compared in three genetic lines of specific pathogen-free chicks inoculated with one of two doses of a nephropathogenic strain of avian infectious bronchitis (IB) virus. The mortality rates were influenced primarily by the chick strain, but also by age and dose of virus. Chicks of the inbred S line were highly susceptible. After inoculation with a low dose of virus at 2 and 4 weeks of age, mortality was 90 and 45%, respectively. Chicks of the HWL non-inbred line were also susceptible, with mortality rates after inoculation at 2 and 4 weeks of age of 70 and 25%, respectively. Chicks of the inbred W line were resistant and non-significant mortality of 10% occurred only in 2-week-old chicks inoculated with a high dose of virus. Viral distribution in tissues of susceptible S and resistant W chicks did not differ, and virus was present in the trachea, lung and kidney of chicks from both lines throughout the acute phase (between days 3 and 7) of infection. Viral titres in the trachea and kidney in susceptible S chicks were slightly but not significantly higher than in the other chicks during the acute phase of infection. Histopathological assessment indicated an earlier onset of a regenerative phase in the trachea of W chicks than in S chicks. S chicks, in contrast to W chicks, showed no signs of renal regeneration. Additionally, the kidneys of S chicks differed from those of W chicks in showing more severe nephritis, more tubular necrosis and less heterophil infiltration and lymphocytic response throughout the acute phase of infection. The results indicate that chicken lines may differ greatly in their susceptibility to fatal IB nephritis and that resistance is likely to be under the control of immune responses to viral infection.     

Leukocyte subpopulations in kidney and trachea of chickens infected with infectious bronchitis virus

Using immunohistochemical methods, we studied the nephropathogenicity of the infectious bronchitis virus (IBV)-strain V1648- and the leukocyte phenorypes in the pathological lesions in the kidneys and the trachea formed after inoculation with this virus strain. One-day-old WLA chickens were intravenously inoculated, and after 5, 7 and 11 days their kidneys, trachea and lungs were removed. Monoclonal antibodies were used to detect viral antigen, and lymphoid and non-lymphoid cell populations. In serial sections, the detection of the viral antigen was correlated to the phenotypes of the cells. At days 5 and 7 after inoculation, viral antigen was detected in the epithelium and the interstitium of the kidney tubuli and in the epithelium of the trachea. The infiltrated cells in these tissues were mainly of the T cell phenotype. The cellular immune reaction was correlated with the detection of viral antigen.     

Morphogenesis of avian infectious bronchitis virus in primary chick kidney cells

Summary Primary chick kidney cells were infected with avian infectious bronchitis virus (IBV) and examined by electron microscopy. Virus particles entered the cells by viropexis and distinction could be made between engulfment by cell processes (phagocytosis) and entry by micropinocytosis in coated transport vesicles.Virus maturation occurred by budding into either the cisternae of the endoplasmic reticulum or cytoplasmic vacuoles, and evidence was obtained to suggest that the viral surface projections could be attached during the budding process. Late in infection large numbers of virus particles were present, mainly in cytoplasmic vacuoles, and the majority were released by cell lysis. Release by fusion of vacuoles with the plasma membrane was also observed, and individual virions could be transported from the endoplasmic reticulum to the surface within coated vesicles.With 10 Figures     

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.     

Protection of chickens against renal damage caused by a nephropathogenic infectious bronchitis virus

The ability of the infectious bronchitis (IB) Ma5 and 4/91 live-attenuated vaccines to protect against kidney damage caused by a nephropathogenic strain of IB virus (B1648) was investigated. Protection parameters considered were gross and microscopic renal pathology, and the use of a polymerase chain reaction to detect IB RNA in kidney tissue. By each parameter, Ma5 vaccine alone provided poor protection, but 4/91 alone or the combined program both protected well.     

Replication and cytopathogenicity of avian infectious bronchitis virus in chicken embryo kidney cells

Archives of Virology - The formation of syncytia and their subsequent necrosis were the characteristic cytopathic effects produced in chicken embryo kidney cell cultures infected with the IBV 42...     

Plastic multiwell plates to assay avian infectious bronchitis virus in organ cultures of chicken embryo trachea.

Simple assay systems for infectivity titrations of avian infectious bronchitis virus (IBV) in chicken embryo trachea organ cultures (OC) were developed using plastic multiplate wells with one tracheal ring per well; these assays appeared to be much more satisfactory than the conventional rolled-tube method. The medium, 0.05 M HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid)-buffered Eagle minimal essential medium was not changed during observation. A medium containing 0.4% bovine serum albumin did not influence the virus yield, but did stabilize virus viability during storage. Reproducibility of results obtained in the OC system was confirmed by performing replicate titrations of the Beaudette strain with three different passage histories. The mean virus titers in the OC were lower than those in chicken embryos, depending on the IBV passage histories. The time required for ciliostasis was related not only to the concentration of virus, but also to the IBV passage history. Application of OC techniques for the constant serum-variable virus neutralization test gave low neutralization indexes with excellent reproducibility as compared with those obtained in the chicken embryo assay system. Also, the slopes of neutralization curves obtained by assays in OC were less steep than those seen in the chicken embryo system.     

Presence of viral antigens and antibody in the trachea of chickens infected with avian infectious bronchitis virus

Following infection of chickens with infectious bronchitis virus (strain M41) viral antigens were detected by immunofluorescence in the basal layer of the tracheal mucosal epithelium for 44 days. The enzyme-linked immunosorbent assay (ELISA) first detected virus-specific antibody in tracheal washes 7 days after infection and at 10 days these antibodies reached a level that was maintained for at least 44 days, although there was considerable variation between chickens. In contrast a neutralisation test did not detect antibody until day 20 ; titres were in the range 2.2 to 3.2 log2 reaching a maximum at day 27. ELISA detected anti-viral IgA in tracheal washes only on day 7, whereas IgG was detected in all samples containing anti-viral antibody. Serum anti-viral antibodies were detected by ELISA at 7 days and reached peak titres at 10 days, which were maintained. In contrast, serum neutralising antibodies were first detected at 10 days and increased to peak titres on day 24. The implications of the differences between the results of ELISA and neutralisation tests are discussed.     

Epitopes on the spike protein of a nephropathogenic strain of infectious bronchitis virus

Summary Infectious bronchitis virus (IBV), the first coronavirus described, was initially associated with severe respiratory disease. However, outbreaks have more recently also been associated with nephropathogenesis. Topographically interrelated antigenic determinants of the nephropathogenic Gray strain of IBV were characterized using eleven monoclonal antibodies (MAbs). Four MAbs (IgG 2a) defined epitopes that were both conformation-independent and group specific, reacting with Gray, Arkansas (Ark), and Massachusetts 41 (Mass 41) strains. Seven MAbs (IgG 1) defined conformation-dependent epitopes that could differentiate the Gray from the Ark and Mass strains. The spike protein specificity of the MAbs was determined with the conformation-independent MAbs and one MAb that reacted only in non-denaturing western blot assays. Competitive binding studies using these MAbs suggested a high degree of functional dependency among the associated epitopes as might be expected with a protein of complex secondary and tertiary structure. At least two regions associated with complete protection of infected embryos were identified that consisted of both conformation-dependent and independent epitopes. However, a non-neutralizing MAb, which did not protect the embryo from gross lesions, did inhibit virus-induced lesions and replication in the kidneys. These MAbs should be valuable tools in studying IBV pathogenesis.