Evaluation of a Commercial Modified Live Virus Fowl Pox Vaccine for the Control of "Variant" Fowl Poxvirus Infections

Fatunmbi, Olufemi O.; Reed, Willie M.

doi:10.2307/1592268

Cited by 32 publications

(20 citation statements)

References 2 publications

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“…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).…”

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

confidence: 99%

“…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).…”

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

confidence: 99%

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

confidence: 99%

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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“…However, these vaccines no longer seem to be effective since, in recent years, several outbreaks of fowlpox have occurred in previously vaccinated flocks, resulting in significant economic losses (Fatunmbi & Reed, 1996;. Although clinical signs of the disease usually include the development of skin lesions on the unfeathered areas (cutaneous form), mucosal lesions involving the mouth, esophagus and/or trachea (diphtheritic form) have been observed during most of the outbreaks .…”

Section: Introductionmentioning

confidence: 99%

Re-emerging fowlpox: Evaluation of isolates from vaccinated flocks

2000

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Vaccines of fowlpox or pigeonpox virus origin have been routinely used for more than half a century to prevent fowlpox in commercial poultry in areas where the disease is endemic. However, in recent years, outbreaks of fowlpox have occurred in previously vaccinated flocks. One possible explanation for this problem is the emergence of variant strains of fowlpox virus (FPV). A second, not mutually exclusive, postulate is that the novel FPV exhibit enhanced virulence due to the integration of avian reticuloendotheliosis virus (REV) into their genomes. To determine if immunological variance and/or the acquisition of REV nucleotide sequences could be responsible for the ineffectiveness of current vaccines, the ability of two commercial vaccine viruses and four, recently isolated, field strains to protect chickens against challenge with one of the more virulent field viruses was evaluated. Adequate protection was provided by the vaccines and two of the four field isolates. Interestingly, the two isolates that were not protective, as well as the challenge strain, failed to elicit a strong humoral antibody response. As to possible REV participation, an antibody response to this virus was only found in those chickens receiving one of the "protective" field strains, despite the presence of REV coding sequences in all four field viruses. While REV long terminal repeats of variable lengths were detected in the genomes of all FPV strains used in this study, only the DNAs of the field strains appeared to have intact REV provirus. This retention of foreign DNA may enhance the pathogenesis of FPV, although other factors may be involved.

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“…The difference in restriction and antigen patterns observed between vaccine strains and field isolates is not unexpected because differences in these strains have also been shown in cross-protection studies. 7 However, the high degree of genetic and antigenic relatedness observed among Vac-82, FI-38, and FI-42 is surprising because Vac-82 is a vaccine strain, whereas FI-38 and FI-42 are field isolates. Furthermore, FI-38 and FI-42 were shown to be biologically different 6 despite their high genetic and antigenic relatedness, albeit such a difference may be attributed to the almost 1% difference observed between them.…”

Section: Discussionmentioning

confidence: 99%

“…7 However, the high degree of genetic and antigenic relatedness observed among Vac-82, FI-38, and FI-42 is surprising because Vac-82 is a vaccine strain, whereas FI-38 and FI-42 are field isolates. Furthermore, FI-38 and FI-42 were shown to be biologically different 6 despite their high genetic and antigenic relatedness, albeit such a difference may be attributed to the almost 1% difference observed between them. At this point, whether FI-38 and FI-42 could possibly have evolved from Vac-82 remains a conjecture, and the situation is confounded even further by the lack of information regarding the source of fowlpox vaccine used to vaccinate the flock from which FI-38 and FI-42 were isolated.…”

Section: Discussionmentioning

confidence: 99%

Use of Restriction Fragment Length Polymorphism, Immunoblotting, and Polymerase Chain Reaction in the Differentiation of Avian Poxviruses

Tadese

Reed

2003

J VET Diagn Invest

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Abstract. Restriction deoxyribonucleic acid (DNA) fragment profile analysis coupled with immunogenic protein profile analysis has provided useful information in determining the differences between vaccine strains and field isolates of fowlpox virus (FPV). The DNA of strains examined in this study clearly fell into 3 minor groups of restriction patterns similar but distinct from one another: restriction patterns exhibited by the vaccine strains except 1 vaccine strain, Vac-82; restriction profiles indicated by Vac-82 and field isolates FI-38 and FI-42; and restriction patterns indicated by field isolates FI-43, FI-51, FI-54, and FI-56. Furthermore, when the strains were analyzed and compared by immunoblotting analysis, they showed group differences similar to the differences in restriction profiles. Both techniques provided high sensitivity in verifying differences between vaccine strains and field isolates of FPV. The disparity found in restriction fragments or immunogenic protein profile between vaccine strains and field isolates does not exclude the appreciable high degree of DNA sequence conservation and homology. However, the minor disparity observed in these strains suggests a molecular basis for why vaccinated commercial flocks could have continually been infected by variant strains of FPV. A rapid and sensitive polymerase chain reaction method, which amplified a product from the 4b core protein gene of the FPV genome, was developed for identification and differentiation of members of the genus Avipoxvirus. Whereas total DNA from either vaccine strains or field isolates was used as template for amplifying a predicted product of 578 or 1409 bp, only cleavage of the amplified product (1409 bp) represented an additional detection technique for species differentiation. An attempt to distinguish between strains on the basis of amplification product was partially successful.

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Evaluation of a Commercial Modified Live Virus Fowl Pox Vaccine for the Control of "Variant" Fowl Poxvirus Infections

Cited by 32 publications

References 2 publications

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

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

Re-emerging fowlpox: Evaluation of isolates from vaccinated flocks

Use of Restriction Fragment Length Polymorphism, Immunoblotting, and Polymerase Chain Reaction in the Differentiation of Avian Poxviruses

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