Infectious Bronchitis Virus Types Affecting European Countries-A Review.

Since its first detection in Europe in the 1940s, infectious bronchitis virus has continued to be one of the major respiratory pathogens affecting the European poultry industry. The development of effective and widely used vaccines for both broilers (live attenuated) and breeders and layers (live attenuated and inactivated) helped improve the health and welfare of poultry but never eliminated the problem. The main reason is the continual emergence of new infectious bronchitis variants (serotypes or genotypes). This review discusses the most prevalent genotypes of the last few decades in Europe. Some of these genotypes seem to be local European types; others have an origin outside Europe.

Estudio recapitulativo- Tipos del virus de la bronquitis infecciosa que afectan a los países europeos: Una revisión. Desde su primera detección en Europa en la década de los 1940s, el virus de la bronquitis infecciosa ha seguido siendo uno de los principales patógenos respiratorios que afectan a la industria avícola europea. El desarrollo de vacunas eficaces y ampliamente utilizadas tanto para pollos de engorde (vivos atenuados) como para reproductoras y ponedoras (vivos atenuados e inactivados) ayudó a mejorar la salud y el bienestar de las aves comerciales, pero nunca eliminó el problema. El problema principal es la aparición continua de nuevas variantes de bronquitis infecciosa (serotipos o genotipos). Esta revisión analiza los genotipos más prevalentes en las últimas décadas en Europa. Algunos de estos genotipos parecen ser tipos europeos locales; otros tienen un origen fuera de Europa.

Exploring the impact of physician verbal abuse on perioperative nurses.

The purpose of this study is to explore the incidence and impact of physician verbal abuse on perioperative nurses. Roy's Adaptation Model was used as the framework for this descriptive, exploratory study. Seventy-eight perioperative nurses completed the Verbal Abuse Scale questionnaire. Seventy-one nurses (91%) reported experiencing some type of verbal abuse from a physician during the past year. Results show, however, that nurses use adaptive coping behaviors and problem-focused skills to deal with the abuse.

Whatever happened to the General Surgery graduating class of 2001?

PURPOSE: Nationally approximately 20% of all categorical General Surgery (GS) residents do not complete their GS training. We ranked 57 applicants in the National Residency Match Program (NRMP) in 1996 and matched our final eighth candidate with slot 22. Although clinically stellar, 4 of these 8 residents (50%) opted to switch to different medical specialties. We pondered if other programs had difficulties with the 1996 applicant pool and hypothesized that perhaps higher ranked applicants have greater attrition rates. METHODS: Programs in which our ranked applicants matched were contacted and asked for feedback on trainee performance, research time, attrition, and future plans. RESULTS: Four applicants did not match in GS. Fifty-three surgical interns (46 men, 7 women) in 1996 are now 23 chief residents, 18 senior residents (16 did research time, 1 did an intensive care unit fellowship, and 1 required a year of remediation), and 12 non-GS trainees (orthopedic surgery = 3, anesthesiology = 3, ENT = 1, family medicine = 1, internal medicine = 1, radiology = 1, pathology = 1, and Ph.D. researcher = 1). Clinical performance was similar for both GS trainees and those who dropped out. Residents dropped out after the PG-1 year (n = 7), PGY-2 (n = 3), and 1 each after PGY-3 and PGY-4. Higher ranked applicants were no more likely to drop out than were lower ranked applicants. CONCLUSIONS: Of Mayo Clinic-Rochester-ranked GS categorical applicants in 1996, 23% dropped out of GS. Eleven of 12 dropouts selected a different field of medicine to finish their training. Attrition remains common and problematic both nationally and in individual programs.

Infectious bronchitis virus vaccine interferes with the replication of avian pneumovirus vaccine in domestic fowl.

Experiments were performed in chickens to ascertain whether application of infectious bronchitis (IB) H120 vaccine had an effect on the replication of an attenuated avian pneumovirus (APV) strain, using as indicators virus detection, humoral antibody responses and clinical protection against in vivo APV challenge. A preliminary experiment demonstrated that pharyngeal swabs were as efficient for recovery of APV as were buccal cavity swabs, and that either site was superior to swabbing the nasal cavity. APV was detected to a similar extent by both a reverse transcriptase-polymerase chain reaction (RT-PCR) and virus isolation; therefore, RT-PCR was used in subsequent experiments. In chickens vaccinated with APV alone, APV was detected by RT-PCR in most birds for 1 week after vaccination. When IB vaccine had been applied 1 week earlier, APV detection was delayed and much reduced. This interference by IBV resulted in a lower APV antibody response to vaccination. Following challenge with virulent APV, birds that had been vaccinated with APV alone were fully protected both clinically and virologically. Chickens that had received both vaccines were still protected clinically, but challenge virus could be detected in some pharyngeal swabs 4 days after challenge. In contrast, the APV vaccine had no effect on either the antibody response to the IB vaccine or the level of protection against IB challenge. It is concluded that IB vaccination interferes with the replication of APV, resulting in a reduction in the antibody response but with no adverse effect on the induction of protective immunity.

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.

Cloning, expression and immunogenicity of the avian pneumovirus (Colorado isolate) F protein.

The F protein of the Colorado isolate of avian pneumovirus (APV), expressed from a DNA plasmid, was recognized by antiserum to both A and B subgroup APVs. After two intramuscular injections of turkeys with this plasmid, a homologous antibody response was detected by enzyme-linked immunosorbent assay. This antibody also recognized subgroup A APV. However, there was no neutralization of the Colorado isolate or of subgroup A or B viruses. Although no significant clinical protection was detected following homologous challenge of poults, an anamnestic serological response was seen, suggesting that a systemic antibody response but no local mucosal immunity was induced.

Characterization of infectious bronchitis viruses isolated from outbreaks of disease in commercial flocks in Brazil.

Fifteen isolations of infectious bronchitis (IB) virus were made from a total of 126 Brazilian poultry flocks of all ages that were examined. These flocks (14 chicken and 1 quail) were experiencing a variety of IB-like conditions including respiratory disease, digestive and kidney problems, and drops in egg production. One of the isolates was of the Massachusetts serotype. The remainder were examined by means of cross-neutralization tests in tracheal organ cultures and were shown to belong to at least four antigenic groups, all different from ones described previously in other countries. Some, but not all, of the flocks from which they were isolated had been vaccinated against IB with vaccines of the Massachusetts serotype. In vivo protection studies showed that the MA5 vaccine (of the Massachusetts serotype) protected well against challenge with four of these isolates, representing the different serotypes reported in this study.

Avian pneumovirus infections of turkeys and chickens.

Avian pneumoviruses (APVs) cause major disease and welfare problems in many areas of the world. In turkeys the respiratory disease and the effect on egg laying performance are clearly defined. However, in chickens, the role of APV as a primary pathogen is less clear, although it is widely believed to be one of the factors involved in Swollen Head Syndrome. The mechanisms of virus transmission over large distances are not understood, but wild birds have been implicated. APV has recently been reported in the USA for the first time and the virus isolated was a different type or possibly a different serotype from the APVs found elsewhere. Good biosecurity is crucial for controlling infection and highly effective vaccines are available for prophylaxis. Although different subtypes and possibly different serotypes exist, there is good cross protection between them. Diagnosis is usually based on serology using ELISAs, but the available kits give variable results, interpretation is difficult and improved diagnostic tests are required.

Avian rhinotracheitis.

Turkey rhinotracheitis, now commonly termed avian pneumovirus (APV) infection, is associated with serious welfare and economic problems in susceptible populations of turkeys and probably also of chickens. The infection principally affects the upper respiratory tract, although egg-laying performance may also be affected in breeding turkeys. Secondary infections exacerbate the effects of the primary virus infection. The virus persists for only a short time both in the host and in the environment and is not known to be transmitted via the egg. Highly effective vaccines are available to control APV infections, and hence good biosecurity and careful use of these vaccines should enable infection to be controlled and spread restricted. Diagnosis and surveillance are normally performed serologically using enzyme-linked immunosorbent assays (ELISAs). Several different ELISA kits are available commercially, but these give variable results and are not wholly satisfactory since interpretation of results is difficult.

Avian pneumovirus infection of laying hens: experimental studies.

Administration of a virulent strain of avian pneumovirus (APV) to specific pathogen free laying hens by the oculonasal route failed to induce a drop in egg production or any adverse effects on eggshell quality. However, intravenous (i.v.) inoculation of the same strain caused a substantial drop in egg production and a high incidence of soft and thin-shelled eggs. Some respiratory signs were also observed and the hens appeared sick, with diarrhoea being observed in approximately one-half of the hens between 4 and 11 days post-inoculation (p.i.). APV antigen was detected in the oviduct epithelium up to 9 days p.i. This challenge model was then used to investigate the efficacy of live attenuated turkey rhinotracheitis (TRT) vaccine administered alone at 1 day old, or an inactivated TRT vaccine (at 16 weeks), or a combined programme using both vaccines, in protecting against this challenge. Neither the live nor the inactivated vaccine alone protected against clinical signs (respiratory infection or diarrhoea). However, the inactivated, but not the live, vaccine did protect against the effect of the i.v. challenge on laying performance. In contrast, the combined vaccination programme protected completely against both clinical signs and poor egg-laying performance. This protection lasted until at least 60 weeks of age. On the basis of the results with this experimental model, it is concluded that the use of live priming followed by administration of inactivated TRT vaccine is necessary to provide complete protection of laying chickens against APV challenge.

Breadth of protection of the respiratory tract provided by different live-attenuated infectious bronchitis vaccines against challenge with infectious bronchitis viruses of heterologous serotypes.

The regime of administering the infectious bronchitis (IB) Ma5 vaccine (Massachusetts serotype) at 1 day old and the heterologous 4/91 vaccine at 2 weeks of age, was shown to be highly effective in protecting the respiratory tract of specified pathogen free chickens. Protection, as measured by assessing ciliary activity of the tracheal epithelium following challenge, was excellent against challenge at 5 weeks of age with IB strains of many serotypes, isolated from disease outbreaks in different parts of the world. This vaccination protocol was more effective than revaccination with a vaccine of the same serotype as the first vaccine. Furthermore, significantly better protection was seen when the Ma5 vaccine was given before, rather than at the same time as or following, the 4/91 vaccine. It is suggested that the use of these two IB vaccines will frequently broaden the protection possible against challenge with IB isolates of many different serotypes, without the need to develop a new IB vaccine to combat each new IB serotype that emerges.

Intracloacal infection with avian infectious bronchitis virus.

An infectious bronchitis virus (IBV) strain HS-91 isolated from kidneys of chicks which died of nephrosis was inoculated via the cloaca of specific pathogen-free (SPF) chicks. These chicks showed more severe clinical signs, grosser kidney lesions and higher mortality than chicks inoculated with the same IBV strain via the trachea.

The use of virus isolation, histopathology and immunoperoxidase techniques to study the dissemination of a chicken isolate of avian pneumovirus in chickens.

A subgroup B isolate of turkey rhinotracheitis virus (TRTV) or avian pneumovirus (APV), obtained from a flock of commercial breeding chickens experiencing poor egg production, mortality and swollen head syndrome, was shown to cause substantial respiratory signs in both young SPF chickens and chicks with high levels of maternally derived TRT antibodies. This isolate replicated to high titre in the respiratory tract of experimentally inoculated SPF chickens for approximately 5 days after inoculation, but was recovered only occasionally after that time. It was never recovered from non-respiratory tract tissues. A detailed, sequential histological and immunoperoxidase study was performed. This revealed that, whilst TRT virus could be demonstrated consistently in the epithelium of upper respiratory tract tissue, although only for a short time after inoculation, the damage which it caused was minimal and recovery was rapid. This study, using a pathogenic TRT isolate obtained from diseased chickens, provides clear evidence that TRT virus can cause damage to the respiratory tract of chickens and that this damage is both localized and short lived.

Relationship between sequence variation in the S1 spike protein of infectious bronchitis virus and the extent of cross-protection in vivo.

The notion that the S1 subunit of the spike glycoprotein (S) of infectious bronchitis virus (IBV) is the major inducer of protective immunity has been examined. Groups of 10 1-day-old chicks were vaccinated with isolate UK/6/82 and challenged in-tranasally 3 or 6 weeks later with strains whose S1 protein differed from that of UK/6/82 to different extents: NL/D207/79, UK/142/86 and UK/167/84 (2%), UK/123/82 (4%), UK/918/67 (19%), USA/M41/41 and Portugal/322/82 (20%; both of the Massachusetts serotype), and NL/D1466/79 (49%). Four days after challenge tracheas were removed and observed for ciliary activity. Overall, the degree of cross-protection induced by UK/6/82 diminished as the similarity of the S1 proteins diminished, although in only two cases was the protection induced statistically less (P< 0.10) against the heterologous isolates than against the homologous strain. Even when a group as a whole was poorly protected against heterologous challenge, some individual chicks, including some challenged with D1466, exhibited high protection of the trachea. Conversely, in groups where protection was high overall, a few individuals were poorly protected. The results broadly support the view that differences in the sequence of the S1 protein do contribute to the ability of an IBV strain to break through the immunity induced by another strain. However, they also indicate that some conserved sequences in S1 and/or epitopes in the other, less variable, proteins also contribute to immunity. Moreover, individual chicks can differ greatly in their response to vaccination with IBV, a factor which should not be overlooked.

Demonstration of serum-neutralising antibody to turkey rhinotracheitis virus in serum from chicken flocks in Japan.

Since between 1989 and 1991, broiler, broiler breeder and layer chickens reared in three different prefectures of Japan, Hyogo, Ibaraki, and Miyazaki, were diagnosed clinically as having swollen head syndrome (SHS) these flocks were survey for antibody to turkey rhinotracheitis (TRT) virus using a serum neutralisation (SN) test. TRT-specific SN antibody was found in flocks of chickens in 2 out of the 3 prefectures. Thereafter, particular in the summers of both 1993 and 1994 outbreaks of SHS occurred in almost all areas of major chicken production in Japan. Almost chicken flocks affected by SHS possessed TRT SN antibody. No chicken sera collected between 1972 and 1988 possessed any SN antibody to TRT virus. It is suggested that in Japan, TRT virus is widely prevalent in areas of major poultry production.

An experimental turkey rhinotracheitis (TRT) infection in breeding turkeys and the prevention of its clinical effects using live-attenuated and inactivated TRT vaccines.

The experimental inoculation of 38-week-old turkey hens with a pool of field isolates of turkey rhinotracheitis virus (TRTV) induced a marked respiratory infection and a substantial drop in egg production. Administration of a live-attenuated TRT vaccine at 1 week of age did not protect the layers against respiratory infection, but provided good protection against the effects of challenge on laying performance. However, a combination of live priming followed by injection of inactivated vaccine provided excellent protection against both respiratory infection and drops in egg production.

A survey of the presence of a new infectious bronchitis virus designated 4/91 (793B).

On the basis of virus isolation and the demonstration of specific neutralising antibody in sera, infectious bronchitis virus (IBV) 4/91 (commonly called 793B) has been shown to be present in broiler, breeder and layer flocks of chickens in many parts of western Europe and also in Thailand and Mexico. These flocks had all been vaccinated against infectious bronchitis and the need for improved methods to control this new virus, still prevalent at least four years after it was first isolated, is discussed.

Comparison of the susceptibility of chicks of different ages to infection with nephrosis/nephritis-causing strain of infectious bronchitis virus.

Two- and 6-week-old chicks were inoculated with the Kagoshima-34 strain of avian infectious bronchitis virus. Serum, bile, Harderian gland, lachrymal fluid, saliva and tracheal washings were collected and their antibody content determined using neutralisation tests. The neutralising antibody (NA) in the serum and bile was detected earlier and in slightly higher concentration in the 6-week-old chicks. Although there was no marked difference in the levels of NA in other body fluids, it was detected earlier in the 6-week-old chicks. In both experiments, the clinical signs were more severe in the 2-week-old chicks. Recovery of virus from the trachea of both ages was not different but virus was recovered for longer in the lungs, kidneys and colon of the 2-week-old chicks. This is the first report wherein IBV-neutralising antibody in the bile is described.

Protection against turkey rhinotracheitis pneumovirus (TRTV) induced by a fowlpox virus recombinant expressing the TRTV fusion glycoprotein (F).

A recombinant fowlpox virus was produced which expressed the fusion protein (F) of turkey rhinotracheitis virus (TRTV), a pneumovirus. Turkey poults were vaccinated twice, at an interval of 2 weeks, intramuscularly and by wing web on each occasion, with the recombinant or a control fowlpox virus. Two weeks after the second vaccination the poults were challenged superconjunctivally and intranasally with virulent TRTV. A partially protective immune response was achieved; turkeys vaccinated with the F recombinant showed milder clinical signs and 1000-fold less challenge virus was recovered from the nose and trachea compared with turkeys that had been vaccinated with control fowlpox virus. Expression of the F protein induced antibodies which were detectable both by an ELISA and a virus neutralization test. These results show that the immune responses to the F protein play a major role in protection against TRTV and indicate that recombinant viruses expressing the TRTV F protein have potential as vaccines against TRT.