The minimum protective dose of the herpesvirus turkeys vaccine against Marek's disease

Purchase, H. G.; Okazaki, W.; Br, Burmester

doi:10.1136/vr.91.4.79

Cited by 22 publications

(8 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We found that 1.5 PFU of cell-free HVT vaccine was required to induce viremia in 50% of antibodynegative line P chickens. This value correlates well with previous ID 50 data (Churchill and Baxendale, 1972;Patrascu et al, 1972;Purchase et al, 1972) and supports the validity of our in vitro assay procedure. We found only a negligible (9.7%) drop in titre of cell-associated vaccine after 4 hours at 4°C whereas these conditions produced a 22.7% drop in the titre of cell-free HVT vaccine; the drop in cell-free HVT titre was even more severe under conditions of continuous agitation (Table 1).…”

Section: Vaccine Titresupporting

confidence: 80%

Differential effect of maternal antibodies on efficacy of cellular and cell‐free Marek's disease vaccines

Witter

Burmester

1979

Avian Pathology

View full text Add to dashboard Cite

Section: Vaccine Titresupporting

confidence: 80%

Differential effect of maternal antibodies on efficacy of cellular and cell‐free Marek's disease vaccines

Witter

Burmester

1979

Avian Pathology

View full text Add to dashboard Cite

“…The challenge times used in this study (14, 21 and 28 d.p.v. ) were selected to enable sampling of birds for vaccine virus measurement at several time-points prior to challenge, and are comparable with those used in previous studies on vaccinal protection (de Boer et al, 1981(de Boer et al, , 1987Purchase et al, 1972). Birds were kept for a further 53 days after the final challenge, and were monitored for morbidity and mortality.…”

Section: Methodsmentioning

confidence: 98%

“…Responses of chicks to MD vaccines, including CVI988 (de Boer et al, 1981(de Boer et al, , 1986(de Boer et al, , 1987 and HVT (Purchase et al, 1972;Basarab & Hall, 1976;Eidson et al, 1978), have previously been measured by viraemia assay to confirm replication of vaccine virus in the blood, by PD 50 assay to show immune protection against challenge virus, and by serological assay to demonstrate antibodies against vaccine virus. Our test quantifies CVI988 in chicks by measurement of viral DNA in feather tips.…”

Section: Correlation Of Protection With Cvi988 Level In Feathersmentioning

confidence: 99%

Correlation of Marek's disease herpesvirus vaccine virus genome load in feather tips with protection, using an experimental challenge model

Baigent

Smith

Currie³

et al. 2007

Avian Pathology

View full text Add to dashboard Cite

We previously developed a real-time polymerase chain reaction (PCR) assay for absolute quantitation of serotype 1 Marek's disease virus in feather tips of chickens, and this has been used clinically to monitor a flock's response following vaccination with CVI988, an attenuated serotype 1 strain. The level of vaccine virus in feather tips associated with protection against challenge by virulent virus is not known. Here, we used an experimental challenge model, in which one dose of vaccine gives over 90% protection against mortality, to investigate correlation between the CVI988 level in feathers and protection. One-day-old chickens were vaccinated with 1, 0.1 or 0.01 commercial dose of CVI988 vaccine, and were then challenged with a virulent strain (RB-1B) 14, 21 or 28 days later. Replication of CVI988 virus was followed in each bird by real-time PCR analysis of feather DNA samples. Since the PCR does not differentiate between CVI988 and RB-1B, samples were taken only prior to challenge to ensure that the virus being measured was CVI988. Administration of one dose of vaccine ensured a uniform, rapid and high replication amongst birds, while replication following administration of the 0.1 or 0.01 dose was very variable. However, given time, a low early level of vaccine virus eventually replicated to high levels in some birds. Both the dose of vaccine virus administered and the level of vaccine virus in feather tips at 13 days post vaccination showed significant correlation with protection against challenge. A level of CVI988 vaccine virus of 132 genome copies/10000 feather tip cells was calculated to be the level required for 90% protection in this experimental model. The potential of this assay, and its limitations for monitoring protection in the field, are discussed.

show abstract

“…Following demostration of the efficacy of using lyphilized cell-free HVT as a vaccine against Marek's disease (MD) (Calnek et al, 1970;Churchill, 1971;Patrascu et al, 1972;Purchase et al, 1972;Zanella, 1971;Zanella ef a/., 1973;Zygraich ef a/., 1972), efforts have been made to improve the techniques of vaccine preparation, as well as to develop methods of assay in vitro and in vivo.…”

Section: Introductionmentioning

confidence: 99%

Lyophilized turkey herpesvirus (HVT): Stability of vaccine and minimum protective dose

Zanella

Bettoni

Mambelli

1974

CAVP

View full text Add to dashboard Cite

SUMMARYThe research reported showed that: the stability of cell-free HVT vaccine, Iyophilized and sealed under vacuum, is very high: after one year at 4°-6°C and after 10 days at 37°C the titre decreased only about 0.4 log 10 ; the stability of the vaccine, when reconstituted for use in the diluent (sucrose-phosphate buffer), is high (80%) for at least 2 hours; the degree of protection, found in 3 tests, was about 90% with an inoculum of 20 to 100 pfu, and the PD 50 was 4.9 pfu of virus per chick.

show abstract

The minimum protective dose of the herpesvirus turkeys vaccine against Marek's disease

Cited by 22 publications

References 0 publications

Differential effect of maternal antibodies on efficacy of cellular and cell‐free Marek's disease vaccines

Differential effect of maternal antibodies on efficacy of cellular and cell‐free Marek's disease vaccines

Correlation of Marek's disease herpesvirus vaccine virus genome load in feather tips with protection, using an experimental challenge model

Lyophilized turkey herpesvirus (HVT): Stability of vaccine and minimum protective dose

Contact Info

Product

Resources

About