Principles of Vaccination

Witter, R. L.

doi:10.1007/978-1-4613-2613-7_8

Cited by 26 publications

(6 citation statements)

References 162 publications

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“…First, from 1961 to 1970, the period before any MD vaccines were available (Davison and Nair 2004), we see that leukosis condemnation rates rose rapidly, increasing by more than tenfold before leveling off. Second, from 1971 to 1983, the period after the first generation Herpesvirus of Turkeys (HVT) vaccine was licensed and before the second generation bivalent vaccine was licensed (Witter 1985), leukosis condemnation rates declined to a slightly lower rate than that of the early 1960s. The majority of this decline took place over the first several years after the HVT vaccine was introduced.…”

Section: Resultsmentioning

confidence: 99%

An observational study of the temporal and spatial patterns of Marek's-disease-associated leukosis condemnation of young chickens in the United States of America

Kennedy

Dunn

et al. 2015

Preventive Veterinary Medicine

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Marek’s disease, a disease primarily affecting immature chickens, is a worldwide problem that has on at least three occasions threatened the poultry industry in the United States. A rich dataset to study the epidemiology of this disease is available because the United States Department of Agriculture has required mandatory inspections of all commercially sold poultry of significant scale since the mid-20th century with over 99% of all chickens inspected. This dataset includes monthly totals aggregated by state since 1961 of the number of “young chickens” inspected and the number with “leukosis”, a condemnation category that is almost always associated with Marek’s disease in this category of birds. The objective of this study was to analyze temporal and spatial patterns in this condemnation data to gain insight into the ecology and epidemiology of the causative virus. We extracted visual patterns in the data using seasonal trend decomposition, and we tested for statistical significance using extended linear modeling techniques. The analysis confirmed previous findings that there are differences in leukosis condemnation rates between states, across years, and within years. The analysis also revealed several patterns not previously highlighted, including spatial and temporal autocorrelations in leukosis condemnation, changes to the amplitude of seasonality over time, and increasing within-year variation in condemnation rate over time. These patterns suggest that locally shared farm practices, virus transmission between farms, or viral persistence may be important to understanding the dynamics of the disease. We also discuss the plausibility of other potential explanations for these patterns.

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Section: Resultsmentioning

confidence: 99%

An observational study of the temporal and spatial patterns of Marek's-disease-associated leukosis condemnation of young chickens in the United States of America

Kennedy

Dunn

et al. 2015

Preventive Veterinary Medicine

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“…The salient findings of this report are that (i) the complete genome of the attenuated MDV-1 strain 584Ap80C (38) was cloned as an infectious BAC and that (ii) a recently developed recE-catalyzed mutagenesis protocol was successfully applied to delete the essential gB gene from the MDV-1 genome. To our knowledge, the gB-negative virus reported here represents the first MDV-1 mutant with a deletion of an essential gene and demonstrates the power and usefulness of BACs to ana- FIG.…”

Section: Discussionmentioning

confidence: 99%

“…However, after vaccination failures and description of the so-called "very virulent" MDV-1, MDV-2 strains and later attenuated MDV-1 strains (e.g., strain Rispens CVI 988) have been used in vaccine formulations (38,40). In recent years and first reported in the United States, even more virulent MDV-1, "very virulent plus" (vvϩ), MDV-1 variants appeared and caused high mortality in vaccinated flocks (39).…”

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confidence: 99%

Reconstitution of Marek's Disease Virus Serotype 1 (MDV-1) from DNA Cloned as a Bacterial Artificial Chromosome and Characterization of a Glycoprotein B-Negative MDV-1 Mutant

Schumacher

Tischer

Fuchs

et al. 2000

J Virol

190

177

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The complete genome of Marek's disease virus serotype 1 (MDV-1) strain 584Ap80C was cloned in Escherichia coli as a bacterial artificial chromosome (BAC). BAC vector sequences were introduced into the U S 2 locus of the MDV-1 genome by homologous recombination. Viral DNA containing the BAC vector was used to transform Escherichia coli strain DH10B, and several colonies harboring the complete MDV-1 genome as an F plasmid (MDV-1 BACs) were identified. DNA from various MDV-1 BACs was transfected into chicken embryo fibroblasts, and from 3 days after transfection, infectious MDV-1 was obtained. Growth of MDV-1 recovered from BACs was indistinguishable from that of the parental virus, as assessed by plaque formation and determination of growth curves. In one of the MDV-1 BAC clones, sequences encoding glycoprotein B (gB) were deleted by one-step mutagenesis using a linear DNA fragment amplified by PCR. Mutant MDV-1 recovered after transfection of BAC DNA that harbored a 2.0-kbp deletion of the 2.6-kbp gB gene were able to grow and induce MDV-1-specific plaques only on cells providing MDV-1 gB in trans. The gB-negative virus reported here represents the first MDV-1 mutant with a deletion of an essential gene and demonstrates the power and usefulness of BACs to analyze genes and gene products in slowly growing and strictly cell-associated herpesviruses.

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“…Vaccination has been widely used for control of MD, with turkey herpesvirus (HVT) being the most widely used of the vaccine types at present (Witter, 1985). Very virulent MD viruses have been described which are poorly protected against by vaccination with HVT (Eidson et al, 1978;Eidson et al, 1981;Schat et al, 1982;Witter, 1982Witter, , 1988Witter & Fadly, 1980).…”

Section: Introductionmentioning

confidence: 99%

Marek's disease virus isolates with unusual tropism and virulence for ocular tissues: Clinical findings, challenge studies and pathological features

et al. 1991

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SUMMARYOutbreaks of Marek's disease (MD) were diagnosed in two flocks from the same company. Clinical signs, mainly blindness (>90%), but also depression, mild paralysis, and 11 to 12% mortality by 20 weeks of age were observed. MD virus, serotype 1 was isolated. The isolates were designated NC-1 (flock 1) and NC-2 (flock 2).Challenge experiments were conducted with these isolates and with two reference MD virus strains (JM/102W and Md5) in unvaccinated, turkey herpesvirus-(HVT) vaccinated and bivalent-(HVT and SB-1) vaccinated chickens. Blindness, gross ocular lesions and tumour formation were observed in a high proportion of all groups challenged with NC-1 and NC-2 when compared with chickens challenged with JM/102W and Md5.In chickens challenged with isolates NC-1 and NC-2, corneal changes included oedema, midstromal cellular infiltration consisting of macrophages, lymphocytes, plasma cells and lesser numbers of heterophils, collagen degeneration and keratic precipitates consisting primarily of macrophages covering the central endothelium. Eosinophilic intranuclear inclusion bodies were present in mononuclear cells infiltrating the cornea. Changes in the uveal tract consisted of inflammatory cell infiltrates similar to those present in the cornea. Retinal lesions included disruption of the retinal pigmented epithelium, inflammatory cell infiltration in the subretinal space, photoreceptor degeneration and in severely affected eyes, necrosis of retinal cellular elements. Pecten changes consisted of necrosis and mononuclear cell infiltration. Intranuclear inclusion bodies were abundantly present in cells of the retina's ganglion and inner nuclear cell layers.The unusual clinical manifestation of MD, the unusual tropism and virulence of NC-1 and NC-2 for ocular tissues and the incomplete protection afforded by conventional vaccination suggest that these isolates may be new pathotypes.

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Principles of Vaccination

Cited by 26 publications

References 162 publications

An observational study of the temporal and spatial patterns of Marek's-disease-associated leukosis condemnation of young chickens in the United States of America

An observational study of the temporal and spatial patterns of Marek's-disease-associated leukosis condemnation of young chickens in the United States of America

Reconstitution of Marek's Disease Virus Serotype 1 (MDV-1) from DNA Cloned as a Bacterial Artificial Chromosome and Characterization of a Glycoprotein B-Negative MDV-1 Mutant

Marek's disease virus isolates with unusual tropism and virulence for ocular tissues: Clinical findings, challenge studies and pathological features

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