Field isolates of fowlpox virus contaminated with reticuloendotheliosis virus

Diallo, Ibrahim S.; MacKenzie, Margaret; Spradbrow, P. B.; Robinson, Wayne F.

doi:10.1080/03079459808419275

Cited by 53 publications

(35 citation statements)

References 19 publications

(18 reference statements)

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“…Simultaneous infection may involve two or more viruses, for example: fowlpox virus (FWPV) and adeno-like virus, herpesvirus or reticuloendotheliosis virus (Diallo et al, 1998;Singh et al, 2000;Diallo et al, 2010). Mixed infection may also involve viruses and bacteria, for example Staphylococcus hyicus and poxvirus (Devriese et al, 1992), C. trachomatis and herpesvirus (Deka et al, 2006), chlamydia and poxvirus (Jacobson and Telford, 1990) or other combinations, for example E. coli and pulmonary aspergillosis (Kim et al, 2003), C. psittaci, fowlpox virus, Haemophilus gallinarum and Ascaridia galli (Malkinson et al, 1987), an Avipoxvirus member, C. psittaci or fungi (Bailey et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

Mixed infection by fowlpox virus and Chlamydophila psittaci in a commercial laying hen flock

Karpińska¹,

Kozaczynski²,

Niemczuk

et al. 2014

Acta Veterinaria Hungarica

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An outbreak of fowlpox occurred in a commercial laying hen flock in one of the western provinces of Poland. Clinical signs suggested fowlpox and the diagnosis was confirmed by histopathological detection of Bollinger bodies within the epithelial cells. Detailed ultrastructural examination revealed an additional concurrent infection with chlamydia-like particles. The particles were identified by PCR as fowlpox virus and Chlamydophila psittaci. It is worth noting that both pathogens can generate morphologic forms capable of prolonged survival and inducing latent and persistent infection. We suggest a possible interaction between the two pathogens on ultrastructural level and assess the clinical consequences of the mixed infection. This study also demonstrates a potential of the transmission electron microscope (TEM) for identifying a superinfection with another pathogen (in this case C. psittaci), which may remain undetected by routine techniques.

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Section: Discussionmentioning

confidence: 99%

Mixed infection by fowlpox virus and Chlamydophila psittaci in a commercial laying hen flock

Karpińska¹,

Kozaczynski²,

Niemczuk

et al. 2014

Acta Veterinaria Hungarica

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“…Although genomic integration of REV into the FWPV genome has only been demonstrated in the last 10 years, the analysis of previous field isolates indicates that such events had occurred 50 years ago (Kim & Tripathy, 2001). In contrast to FWPV field isolates, most FWPV vaccines include only partial REV-LTR insertions of various sizes, with the exception of the Australian vaccine strain FWPV-S, which carries a nearly full-length REV provirus (Diallo et al, 1998;Hertig et al, 1997;Moore et al, 2000;Singh et al, 2000). According to the currently available information, all field FWPV isolates contain the REV-LTR and additional variable provirus fragments; the only known exception is an FWPV isolated in 1956, in which only LTR remnants and not additional provirus genes were found (Boulanger et al, 1998).…”

Section: Fowlpox Virus (Fwpv) Is the Prototype Of The Genusmentioning

confidence: 99%

Integration of the reticuloendotheliosis virus envelope gene into the poultry fowlpox virus genome is not universal

Davidson¹,

Shkoda²,

Perk³

2008

Journal of General Virology

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Fowlpox virus (FWPV) is found worldwide in poultry and wild birds. FWPV is a natural example of recombination between viruses, as reticuloendotheliosis virus (REV) fragments have been found in all poultry FWPVs and these are implicated in virulence alteration. We aimed to determine the commonality of this phenomenon and analysed FWPVs collected from 128 poultry flocks and birds over the last 10 years. Various fragments of both viruses were amplified and sequenced at the FWPV integration site, located between FWPV open reading frames 201 and 203. Seven isolates were found to contain no REV insertions, including fragments of the REV env, gag and 59 REV-long terminal repeat (LTR). We demonstrate here for the first time, the existence of poultry FWPVs without REV inserts (two from chickens, one from turkey FWPV and four from wild birds). The REV inserts were heterogeneous in size. In addition to poultry and wild bird isolates, three FWPV vaccine virus strains were examined and found to contain only remnant REV-LTR and no REV envelope gene fragments. Fowlpox virus (FWPV) is the prototype of the genusAvipoxvirus and has worldwide distribution in the poultry industry. Infection of commercial chickens and turkeys with FWPV induces two forms of disease; the relatively mild form is characterized by the development of cutaneous lesions on unfeathered areas of the skin and the more severe diphtheritic form by lesions on mucous membranes of the respiratory and gastrointestinal tracts. In addition, FWPV infection causes reduced growth rates and egg production (Tripathy & Reed, 2003).Vaccination with various live vaccines is widely practised and was thought to be effective in preventing the disease, at least until 10 years ago; since then, the vaccination efficacy has been doubted (Fatunmbi & Reed, 1996;Tripathy et al., 1998;Singh et al., 2000). The avian retrovirus reticuloendotheliosis virus (REV) (Witter & Fadly, 2003), which has inserted various genomic fragments into FWPV (Garcia et al., 2003;Hertig et al., 1997;Kim & Tripathy, 2001;Moore et al., 2000;Singh et al., 2003), was implicated as being responsible for the FWPV virulence alteration (Garcia et al., 2003;Fatunmbi & Reed, 1996). Subsequently, a field FWPV isolate containing an REV insert was used to create a modified FWPV in which the REV inserts were eliminated (Singh et al., 2005). By comparing the lesions induced by the two versions of the same FWPV, the contribution of the REV insert to the increased virulence of the progenitor FWPV was confirmed. REV-containing FWPV isolates were also found to be responsible for immunosuppression and even dissemination of REV, if a full infective provirus is integrated into the FWPV (Singh et al., 2000).REV integration also occurred in FWPV vaccine strains, leading to their immediate elimination from use (Hertig et al., 1997). Initial observations from commercial flocks suggested that FWPV vaccine contamination with REV caused tumours in the vaccinated birds (Bendheim, 1973;Bagust & Dennett, 1977;Fadly et al., 1996). The link b...

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“…Interestingly, the 3Ј LTR of the provirus in the genome of the S vaccine strain, and presumably in those of the field strains, has undergone rearrangement and lacks part of the U3 and U5 regions and all of the R region (9). Despite these alterations, the integrated retroviruses have maintained infectivity, as evidenced by the generation of anti-REV antibodies (9,22) and the detection of REV (6,9) in chickens infected with FPV field strains and the Australian S vaccine strain.…”

mentioning

confidence: 99%

“…Of more concern is the demonstration that nearly intact REV provirus has remained as an integral part of the DNAs of both Australian and United States field strains of FPV (6,9,13,22) and also in the now discontinued Australian FPV standard (S) vaccine strain (9). Interestingly, the 3Ј LTR of the provirus in the genome of the S vaccine strain, and presumably in those of the field strains, has undergone rearrangement and lacks part of the U3 and U5 regions and all of the R region (9).…”

mentioning

confidence: 99%

Reticuloendotheliosis Virus Sequences within the Genomes of Field Strains of Fowlpox Virus Display Variability

Singh

Schnitzlein

Tripathy

2003

J Virol

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Nine field strains of fowlpox virus (FPV) isolated during a 24-year span from geographically diverse outbreaks of fowlpox in the United States were screened for the presence of reticuloendotheliosis virus (REV) sequences in their genomes by PCR. Each isolate appeared to be heterogeneous in that either a nearly intact provirus or just a 248-or 508-nucleotide fusion of portions of the integrated REV 5 and 3 long terminal repeats (LTRs) was exclusively present at the same genomic site. In contrast, four fowlpox vaccines of FPV origin and three originating from pigeonpox virus were genetically homogeneous in having retained only the 248-bp LTR fusion, whereas two other FPV-based vaccines had only the larger one. These remnants of integrated REV presumably arose during homologous recombination at one of the two regions common to both LTRs or during retroviral excision from the FPV genome. Loss of the provirus appeared to be a natural event because the tripartite population could be detected in a field sample (tracheal lesion). Moreover, the provirus was also readily deleted during propagation of FPV in cultured cells, as evidenced by the detection of truncated LTRs after one passage of a plaque-purified FPV recombinant having a "genetically marked" provirus. However, the deletion mutants did not appear to have a substantial replicative advantage in vitro because even after 55 serial passages the original recombinant FPV was still prevalent. As to the in vivo environment, retention of the REV provirus may confer some benefit to FPV for infection of poultry previously vaccinated against fowlpox.

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Field isolates of fowlpox virus contaminated with reticuloendotheliosis virus

Cited by 53 publications

References 19 publications

Mixed infection by fowlpox virus and Chlamydophila psittaci in a commercial laying hen flock

Mixed infection by fowlpox virus and Chlamydophila psittaci in a commercial laying hen flock

Integration of the reticuloendotheliosis virus envelope gene into the poultry fowlpox virus genome is not universal

Reticuloendotheliosis Virus Sequences within the Genomes of Field Strains of Fowlpox Virus Display Variability

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