345 research outputs found
Two similar commercial live attenuated AMPV vaccines prepared by random passage of the identical field isolate, have unrelated sequences
No full textSince late ‘80 s Avian metapneumovirus subtype A causes sufficient disease in Europe for commercial companies to have started developing live attenuated vaccines. Here, two of those vaccines were fully consensus sequenced alongside their progenitor field strain (#8544). Sequences comparison shows that the attenuation of field strain #8544 was associated with no common substitutions between the two derived vaccines. This finding suggests that the attenuation of field viruses via serial passage on cell cultures or tissues is the result of a random process, rather than a mechanism aiming to achieve a specific sequence. Furthermore, field vaccination strategies would greatly benefit by the unambiguous vaccine markers identified in this study, enabling a prompt and confident vaccines detection
Review of “St. Clive:” An Eastern Orthodox Author Looks Back at C. S. Lewis
No full textReview of C. J. S. Hayward, “St. Clive:” An Eastern Orthodox Author Looks Back at C. S. Lewis (Wheaton, Illinois: C. J. S. Hayward Publications, 2000-19). 381 pages. $49.99. ISBN 9781794669956
Identification of IBV QX vaccine markers: Should vaccine acceptance by authorities require similar identifications for all live IBV vaccines?
No full textBV genotype QX causes sufficient disease in Europe for several commercial companies to have started developing live attenuated vaccines. Here, one of those vaccines (L1148) was fully consensus sequenced alongside its progenitor field strain (1148-A) to determine vaccine markers, thereby enabling detection on farms. Twenty-eight single nucleotide substitutions were associated with the 1148-A attenuation, of which any combination can identify vaccine L1148 in the field. Sixteen substitutions resulted in amino acid coding changes of which half were in spike. One change in the 1b gene altered the normally highly conserved final 5 nucleotides of the transcription regulatory sequence of the S gene, common to all IBV QX genes. No mutations can currently be associated with the attenuation process. Field vaccination strategies would greatly benefit by such comparative sequence data being mandatorily submitted to regulators prior to vaccine release following a successful registration process
Impiego di Metapneumovirus aviare (AMPV) come possibile vaccino vivo ricombinante per l’espressione di proteine immunogene del Coronavirus della Bronchite infettiva
No full textThe study investigates the ability of subtype A Avian metapneumovirus (AMPV) to accept foreign genes and be used as a vector for delivery of Infectious bronchitis virus (IBV) QX genes to chickens. Initially the GFP gene was added to AMPV at all gene junctions in conjunction with the development of cassetted full length DNA AMPV copies. After 3 recombinant viruses had been recovered by reverse genetics, GFP positions supporting gene expression while maintaining virus viability in vitro, were determined. Subsequently, either S1 or nucleocapsid (N) genes of IBV were positioned between AMPV M and F genes, while later a recombinant was prepared by inserting S1 and N at AMPV MF and GL junctions respectively. Immunofluorescent antibody staining showed that all recombinants expressed the inserted IBV genes in vitro and furthermore, all recombinant viruses were found to be highly stable during serial passage. Eyedrop inoculation of chickens with some AMPV-IBV recombinants at one-day-old induced protection against virulent IBV QX challenge 3 weeks later, as assessed by greater motility of tracheal cilia from chickens receiving the recombinants. Nonetheless evidence of AMPV/IBV seroconversion, or major recombinant tracheal replication, were largely absent
Field avian Metapneumovirus evolution avoiding vaccine induced immunity
No full textLive avian metapneumovirus (AMPV) vaccines have largely brought turkey rhinotracheitis (TRT) under control in Europe but unexplained outbreaks still occur. Italian AMPV longitudinal farm studies showed that subtype B AMPVs were frequently detected in turkeys some considerable period after subtype B vaccination. Sequencing showed these to be unrelated to the previously applied vaccine. Sequencing of the entire genome of a typical later isolate showed numerous SH and G protein gene differences when compared to both a 1987 Italian field isolate and the vaccine in common use. Experimental challenge of vaccinated birds with recent virus showed that protection was inferior to that seen after challenge with the earlier 1987 isolate. Field virus had changed in key antigenic regions allowing replication and leading to disease in well vaccinated birds
Molecular investigation of a full-length genome of a Q1-like IBV strain isolated in Italy in 2013
No full textSince 1996 a new Infectious Bronchitis virus (IBV) genotype, referred to as Q1, circulated in China and was reported for the first time in Italy in 2011, associated with an increase of mortality, kidney lesions and proventriculitis. During northern Italian outbreak of respiratory disease in a broiler flock in 2013, an IBV strain was detected by RT-PCR and characterized as Q1-like based on partial S1 sequence. The virus was isolated and named γCoV/Ck/Italy/I2022/13. All coding regions of the isolate were sequenced and compared with 130 complete genome sequences of IBV and TCoV, downloaded from ViPR. This showed the highest identity with a Chinese strain CK/CH/LDL/97I (p-distance=0.044). To identify potential recombination events a complete genome SimPlot analysis was carried out which revealed the presence of possible multiple recombination events, but the minor parent strains remained unknown. A phylogenetic analysis of the complete S1 gene was performed using all complete S1 sequences available on ViPR and showed the isolate clustered with an Q1-like strain isolated in Italy in 2011 (p-distance=0.004) and a group of Chinese Q1-like strains isolated from the mid 90’s (p-distance equal or higher than 0.001). It could be hypothesized that the isolate descended from the Italian 2011 Q1-like strain or was the result of a separate introduction from China through commercial trade or migratory birds; but the data currently available does not distinguish between these possibilities
Rapid detection of subtype B avian metapneumoviruses using RT-PCR restriction endonuclease digestion indicates field circulation of vaccine-derived viruses in older turkeys
No full textLive vaccines predominantly control avian metapneumovirus (aMPV) infection in poultry flocks, but vaccine virus can be found for extended periods after application. The most frequently used aMPV vaccine in Italy, VCO3 subtype B, was shown to contain a unique Tru9I restriction endonuclease site within the amplicons produced by a commonly used aMPV diagnostic reverse transcriptase (RT)-nested polymerase chain reaction (PCR). Analysis of European and database logged subtype B aMPV sequences confirmed that the sequence occurred only in the VC03 vaccine. A subsequent RT-PCR restriction endonuclease study of field samples, collected from turkeys between 2007 and 2012, detected subtype B vaccine-derived strains in 12 of 90 samples tested that were collected from birds under 12 weeks of age
THE PIGEON (COLUMBA LIVIA) IS NOT SENSITIVE TO AVIAN METAPNEUMOVIRUS SUBTYPE B AND DOES NOT PLAY ANY ROLE IN VIRUS SPREAD IN EXPERIMENTAL CONDITIONS
No full textAvian metapneumovirus (AMPV) causes an upper respiratory tract infection in turkeys leading to turkey rhinotracheitis. In other avian species, including chickens, it is also involved in the aetiology of multifactorial diseases such as swollen head syndrome. Sensitivity of wild birds to AMPV and their role in maintaining and spreading the virus to poultry is still a matter of debate. Recently the sensitivity of pigeons to AMPV of subtype A or B has been claimed, based on very limited PCR detections from wild or experimentally infected birds. In order to have conclusive evidence regarding the sensitivity of pigeons to AMPV of subtype B and its role in spreading the virus to turkeys, two experimental trials were planned in secure isolation conditions. In trial 1 two isolators were modified to host turkeys and pigeons in the same environment, separated only by a net. Drinkers were shared between groups. 16 Pigeons were infected with AMPV and housed in one isolator with naïve turkeys. Similarly turkeys were infected and housed with naïve pigeons. Additional turkeys and pigeons were kept in different isolators as uninfected controls. Post-infection clinical signs, virus shedding and immune response were assessed for three weeks. In trial 2, commercial two-weeks old turkeys were divided in two groups of ten and housed in two different isolators. Birds in isolator A were challenged as previously described. Four days post-infection, five 7 weeks old naïve pigeons were introduced in the isolator A and kept with the infected turkeys for 24 hours, then removed, sprayed with 0,5 % of Wirkon S solution. After 10 minutes, pigeons were rinsed with water, dried, and introduced in the isolator B, where 10 naïve turkeys were housed. Clinical sign were monitored for 10 days. Pigeons were found refractory to AMPV experimental infection and neither able to spread the virus to naïve turkeys. Our paper shows that pigeons are highly unlikely to play any relevant role in the environmental spread of subtype B AMPV. Pigeons are not biological vector or reservoir species for AMPV subtype B
Evidenze sperimentali della resistenza del Piccione (Columba Livia) all’infezione da Metapneumovirus aviare e della sua irrilevanza nella trasmissione dell’infezione al tacchino
No full textAvian metapneumovirus (AMPV) causes an upper respiratory tract infection in turkeys leading to turkey rhinotracheitis. In other avian species, including chickens, it is also involved in the etiology of multifactorial diseases such as swollen head syndrome. Sensitivity of wild birds to AMPV and their role in maintaining and spreading the virus to poultry is still a matter of debate. Recently the sensitivity of pigeons to AMPV of subtype A or B has been claimed, based on very limited PCR detections from wild or experimentally infected birds. In order to have conclusive evidence regarding the sensitivity of pigeons to AMPV of subtype B and its role in spreading the virus to turkeys, two experimental trials were planned in secure isolation conditions. In trial 1 two isolators were modified to host turkeys and pigeons in the same environment, separated only by a net. Drinkers were shared between groups. Pigeons were infected with AMPV and housed in one isolator with naïve turkeys. Similarly turkeys were infected and housed with naïve pigeons. Additional turkeys and pigeons were kept in different isolators as uninfected controls. Post-infection clinical signs, virus shedding and immune response were assessed for three weeks. In trial 2, commercial two-weeks old turkeys were divided in two groups and housed in two different isolators. Birds in isolator A were challenged as previously described. Four days post-infection, 7 weeks old naïve pigeons were introduced in the isolator A and kept with the infected turkeys for 24 hours, then removed, sprayed with 0,5 % of Wirkon S® solution. After 10 minutes, pigeons were rinsed with water, dried, and introduced in the isolator B, where 10 naïve turkeys were housed. Clinical sign were monitored for 10 days. Pigeons were found refractory to AMPV experimental infection and neither able to spread the virus to naïve turkeys. Our paper shows that pigeons are highly unlikely to play any relevant role in the environmental spread of subtype B AMPV. Pigeons are not biological vector or reservoir species for AMPV subtype B
A comparison of AMPV subtypes A and B full genomes, gene transcripts and proteins led to reverse-genetics systems rescuing both subtypes
No full textAvian metapneumovirus (AMPV) infection of poultry causes serious disease in most countries and subtype A reverse-genetic (RG) systems have allowed a generation of viruses of known sequence, and proved useful in developments towards better control by live vaccines. While subtype B viruses are more prevalent, bacterial cloning issues made subtype B RG systems difficult to establish. A molecular comparison of subtype A and B viruses was undertaken to assess whether subtype A RG components could be partially or fully substituted. AMPV subtype A and B gene-end sequences leading to polyadenylation are, to our knowledge, reported for the first time, as well as several leader and trailer sequences. After comparing these alongside previously reported gene starts and protein sequences, it was concluded that subtype B genome copies would be most likely rescued by a subtype A support system, and this assertion was supported when individual subtype A components were successfully substituted. Application of an advanced cloning plasmid permitted eventual completion of a fully subtype B RG system, and proved that all subtype-specific components could be freely exchanged between A and B systems
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