Horizontal Transmission of Turkey Herpesvirus to Chickens

Cho, B. R.; Kenzy, S. G.

doi:10.3382/ps.0540109

Cited by 25 publications

(17 citation statements)

References 7 publications

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“…Although not of major relevance to our findings, this was an unexpected observation because lateral spread of HVT among chickens infected early in life is not considered to occur (Cho & Kenzy, 1975). We do not consider that experimental errors are a likely cause of our observations , and we have now detected HVT in unvaccinated incontact birds in a number of experiments with virus detection in different laboratories and using different methods.…”

Section: Discussionmentioning

confidence: 63%

Influence of vaccine deposition site on post-vaccinal viraemia and vaccine efficacy in broiler chickens followingin ovovaccination against Marek's disease

Islam¹,

Walkden‐Brown²,

Wong³

et al. 2001

Avian Pathology

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In ovo vaccination against Marek's disease is a widely used technology in the broiler industry. A series of experiments was carried out to determine the site of vaccine deposition in the egg during automated in ovo vaccination, and the effect of vaccine deposition site and dose on vaccine responses following vaccination with cell-associated herpesvirus of turkeys in commercial broiler chickens. Vaccine deposition site following automated in ovo vaccination was principally influenced by the age of embryo, with egg size having a smaller effect. The frequency of vaccine deposition inside the embryo body increased as incubation progressed from day 17.5 to 19.5. In experiments using manual vaccine deposition intra-embryonically (IE) or extra-embryonically (EE) at day 18.5, EE vaccine deposition resulted in a significantly delayed development of post-vaccinal viraemia relative to both IE vaccination and subcutaneous vaccination at hatch. There were no effects of vaccine dose (2000, 4000 or 8000 plaque forming units) on the timing of post-vaccinal viraemia. The timing of post-vaccinal viraemia was found to be a good indicator of the level of protection provided by the vaccine against challenge with earlier viraemia associated with better protection. IE vaccine deposition induced significantly greater protection than EE deposition against challenge with a virulent strain of Marek's disease virus. IE deposition consistently produced a high level of protection (68 to 84%) irrespective of vaccine dose or challenge day, while EE vaccine deposition produced no or low levels of protection (0 to 27%) depending on the vaccine dose and day of challenge. The growth of challenged chickens was also affected by site of vaccine deposition, with significantly higher live weights at day 56 of age in IE compared with EE vaccinated groups. These data suggest that the site of vaccine deposition within the embryo is an important determinant of the success of in ovo vaccination.

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Section: Discussionmentioning

confidence: 63%

Influence of vaccine deposition site on post-vaccinal viraemia and vaccine efficacy in broiler chickens followingin ovovaccination against Marek's disease

Islam¹,

Walkden‐Brown²,

Wong³

et al. 2001

Avian Pathology

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“…HVT vaccinal virus itself does not transmit laterally to chickens and was not thought to be shed in feather dander (Cho & Kenzy, 1975;Cho, 1976) until recent reports of significant shedding . Indeed, recent developments in technology have meant that all three MDV serotypes can be precisely quantified using real-time quantitative polymerase chain reaction (PCR) from tissues, feathers and poultry dust (Islam et al, 2004(Islam et al, , 2006aBaigent et al, 2005a,b;Abdul-Careem et al, 2006;Renz et al, 2006).…”

Section: Introductionmentioning

confidence: 98%

Kinetics of Marek's disease virus (MDV) infection in broiler chickens 1: effect of varying vaccination to challenge interval on vaccinal protection and load of MDV and herpesvirus of turkey in the spleen and feather dander over time

et al. 2008

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Two experiments in commercial broiler chickens vaccinated with herpesvirus of turkeys (HVT) and challenged with Marek's disease virus (MDV) investigated the effects of the vaccination-to-challenge interval (VCI) on vaccinal protection against Marek's disease, and the kinetics of MDV and HVT load in the spleen and feather dander determined using real-time quantitative polymerase chain reaction. Experiment 1 in isolators tested VCI of 2, 4 and 7 days, while Experiment 2 in floor pens tested VCI of 0, 2, 4, 7 and 10 days. MDV challenge induced gross Marek's disease lesions in 14% to 74% of chickens by 56 days post-challenge. Vaccinal protection increased from approximately 40% to approximately 80% with increasing VCI between days 2 and 7 in both experiments, but not thereafter. MDV was detected in both the spleen and dander at 7 days post-challenge and increased rapidly to approximately 21 days post-challenge, after which levels plateaued, rose or fell gradually depending on treatment. HVT was also shed in significant amounts, 1 to 2 logs lower than for MDV, with a clear peak around 14 to 21 days post-vaccination. Vaccination significantly reduced the log(10)MDV load in the spleen (vaccinated, 2.99+/-0.20/10(6) spleen cells; unvaccinated, 4.60+/-0.23/10(6) spleen cells) and dander (vaccinated, 5.28+/-0.13/mg; unvaccinated, 6.00+/-0.18/mg) from infected chickens. The MDV load had a significant negative association with the VCI and the level of vaccinal protection. Measurement of dander production in Experiment 1 and the dust content of air in Experiment 2, combined with determination of the MDV load in these, enabled estimation of total daily shedding rates of MDV per chicken and of the MDV load in air for the first time.

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“…Unlike virulent MDV, which can effectively spread horizontally between weeks 3 and 5 after infection, resulting in infection of other chickens or reinfection (4,14), the horizontal transmission of avirulent strains is very poor or absent (24). Serotype 2 MDV and CVI988 spread horizontally 2 weeks after immunization (30,31), but neither attenuated MDV nor HVT does so (4,14), even though viral antigens can be detected for a limited period in the feather follicle epithelium of chickens infected with HVT (15,18,31,40). The CVI988 strain initially spread well by contact, but partial flock vaccination does not work in practice, as the spread of the vaccine strain was very poor and not rapid enough to precede infection with virulent strains from the field (1,29).…”

Section: Fig 5 Dynamics Of Neutralizing Antibodies In Spf White Legmentioning

confidence: 99%

Revaccination with Marek's Disease Vaccines Induces Productive Infection and Superior Immunity

Gan

Jin

et al. 2009

Clin Vaccine Immunol

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The most common lymphoproliferative disease in chickens is Marek's disease (MD), which is caused by the oncogenic herpesvirus Marek's disease virus (MDV). The emergence of hypervirulent pathotypes of MDV has led to vaccine failures, which have become common and which have resulted in serious economic losses in some countries, and a revaccination strategy has been introduced in practice. The mechanism by which revaccination invokes superior immunity against MD is unknown. After field trials which showed that revaccination provided protection superior to that provided by a single vaccination were performed, experiments were conducted to explore the interaction between revaccinated chickens and MDV. The results showed that the chickens in the revaccination groups experienced two consecutive productive infections but that the chickens in the singlevaccination groups experienced one productive infection, demonstrating that revaccination of viruses caused the chickens to have productive and then latent infections. Revaccination of the virus induced in the chickens a higher and a longer temporary expansion of the CD8 ؉ , CD4 ؉ , and CD3 ؉ T-lymphocyte subpopulations, stronger peripheral blood lymphocyte proliferative activity; and higher levels of neutralizing antibody than single vaccination. These findings disagree with the postulate that MDV antigens persist, stimulate the immune system, and maintain a high level immunity after vaccination. The suppression of productive infection by maternal antibodies in chickens receiving the primary vaccination and a lower level of productive infection in the revaccination groups challenged with MDV were observed. The information obtained in this study suggests that the productive infection with revaccinated MDV in chickens plays a crucial role in the induction of superior immunity. This finding may be exploited for the development of a novel MD vaccine that results in the persistence of the antigen supply and that maintains a high level of immunity and may also have implications for other viral oncogenic diseases in humans and animals.Herpesviruses are important pathogens associated with a wide range of diseases in human and animals. Marek's disease (MD) is an important, ubiquitous, contagious, and oncogenic disease in chickens caused by Marek's disease virus (MDV), an alphaherpesvirus (12). Apart from its importance in the poultry industry and for animal welfare (5), MD makes a significant contribution to our understanding of herpesvirus-associated oncogenicity due to the many MD lymphomas with a biological nature similar to that of the lymphoid neoplasia associated with human herpesviruses, such as Epstein-Barr virus (17). Studies have suggested that MD is a natural model for lymphomas that overexpress the Hodgkin's disease antigen, CD30 (7), and MD in small animals provides a well-defined model of general tumorigenesis and virus-induced lymphomagenesis (5,7,12,17,22). Unlike human diseases caused by herpesviruses, MD is the first lymphoproliferative disease which is effective...

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Horizontal Transmission of Turkey Herpesvirus to Chickens

Cited by 25 publications

References 7 publications

Influence of vaccine deposition site on post-vaccinal viraemia and vaccine efficacy in broiler chickens followingin ovovaccination against Marek's disease

Influence of vaccine deposition site on post-vaccinal viraemia and vaccine efficacy in broiler chickens followingin ovovaccination against Marek's disease

Kinetics of Marek's disease virus (MDV) infection in broiler chickens 1: effect of varying vaccination to challenge interval on vaccinal protection and load of MDV and herpesvirus of turkey in the spleen and feather dander over time

Revaccination with Marek's Disease Vaccines Induces Productive Infection and Superior Immunity

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