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The effects of dual infection of 1-day-old broiler chicks with a chicken isolate of avian pneumovirus (APV) and a pool of pathogenic Escherichia coli strains were studied by supraconjunctival application of the bacteria simultaneously with the virus, or at 4, 7 or 11 days afterwards. When the agents were given together, the clinical disease was significantly more severe than that caused by the virus alone, but when the bacterium was given later the signs were less severe. None of the infections resulted in swollen head syndrome by 32 days. All mixed infections caused moderate to severe congestion in the turbinates, when birds were examined at 32 days of age, at which time no such lesions were present in birds having been infected with APV alone. E. coli was isolated from almost 100% of birds with mixed infections, while rates of those given only E. coli isolation varied between 56 and 67%. Furthermore, E. coli colony counts were consistently higher from mixed infection groups. Virus persistence in the choanal cleft was slightly prolonged in birds with the simultaneous mixed infection. Although the pool of E. coli included O2, O78 and O18 serotypes, only those of the O2 serotype and a small number of untypable strains were re-isolated from selected mixed and single E. coli-infected groups. Mixed APV and E. coli infection did not affect APV enzyme-linked immunosorbent assay antibody titres at 21 or 32 days. Thus, experimental infection of broiler chicks with APV and E. coli, simultaneously or at intervals afterwards, demonstrated a synergistic effect between the two agents, but none of the infection protocols caused swollen head syndrome. [ABSTRACT FROM AUTHOR]

Summary Three isolates of avian pneumovirus (APV) were isolated in Germany during 1987 and 1988 from turkeys with clinical signs of turkey rhinotracheitis and one was isolated during 1990 from a broiler breeder flock with typical signs of swollen head syndrome. The isolates were typed using type-specific reverse transcriptase-polymerase chain reactions. The three isolates from turkeys were identified as type A, while the isolate from the broiler breeders was type B. During the late 1980s no APV live-virus vaccine was used in poultry flocks in Germany, which is indicative of the presence of both types at that time. Previous isolates detected from elsewhere in Europe during the 1980s had been only of type B. [ABSTRACT FROM AUTHOR]

In longitudinal studies, 13 flocks were swabbed twice each week for the life of the flock (up to 46 days). The swabs were analyzed by type-specific reverse transcriptase polymerase chain reactions. Massachusetts type vaccinal infectious bronchitis virus (IBVs), applied at the hatchery, were usually maximal during the first week, as expected and, notably, remained detectable for 3 to 4 weeks, occasionally longer. IBV of the 793/B type (also known as 4/91 and CR88) was detected in 11/13 flocks (85%). The time of first detection of 793/B varied over several weeks and was sometimes within the first week in low amounts, which increased gradually. In some flocks, detection of 793/B remained intermittent. IBV types D274 and D1466 were each detected once, in the same flock, for short periods, in low amounts, and in the presence of higher amounts of 793/B. In swabs from a further 30 broiler flocks, plus those already mentioned, there was an incidence for 793/B, D274 and D1466 of 79, 10 and 2%, respectively. Avian pneumovirus (APV) (avian or turkey rhinotracheitis virus) vaccines, applied at the hatchery or later, were either not detected or were detected only after a delay of 1 to 3 weeks. In five flocks that received no APV-A vaccine and two flocks that received only APV type A vaccine, field infection by APV type B was detected but only during the last week or so of life. In six flocks that had received an APV-B vaccine, no field APV-B, differentiated from vaccinal APV-B by restriction enzyme analysis, was detected. In swabs from 30 other flocks, the great majority of which had not been vaccinated against APV, the incidence of APV types B and A was 50 and 3%, respectively. The results show (a) that vaccinal IBV can be detected for several weeks, (b) the dominance of the IBV 793/B type and (c) that broiler flocks may be infected simultaneously with several types of IBV. [ABSTRACT FROM AUTHOR]

Cites a survey evaluating the efficacy of infectious bronchitis virus vaccines against a novel genotype, Italy 02, which appears to be widespread throughout Great Britain and western Europe. Vaccination of chicks by spray with a commercial dose of Poulvac IBMM + Ark and Poulvac IB Primer; Findings on the ability of both combination vaccines to give excellent protection against Italy 02 challenge; Clinical characteristics of Italy 02 virus.

Empirically derived live avian metapneumovirus (AMPV) vaccines developed during the late 80s and early 90s have generally performed well in controlling turkey rhinotracheitis. Nonetheless, unstable attenuation was previously demonstrated in an AMPV subtype A vaccine. Until now this had not been investigated in subtype B vaccines due to lack of any similar availability of a vaccine progenitor or its sequence. The publication of the full genome sequence for the VCO3 vaccine progenitor facilitated a conclusive investigation of two AMPVs isolated from poults on a farm which had been vaccinated with VCO3 derived vaccine. Full genome sequencing of the isolates and their comparison to sequences of the vaccine and its progenitor, confirmed their vaccine origin. After determining the absence of extraneous infectious agents, one of these virus isolates was inoculated into 1-day-old turkeys in disease secure isolators and shown to cause disease with a severity similar to that caused by virulent field virus. This suggests that instability in live AMPV vaccines may be generalized and highlights the need for availability of vaccine progenitor sequences for the field assessment of all live viral vaccines. [ABSTRACT FROM AUTHOR]