{
  "abstract": "In this study, we evaluated the replication kinetics and protective efficacy of the gene-deleted Marek’s disease (MD) vaccine strain SC9-1 in specific-pathogen-free (SPF) chickens immunized with different doses. Chickens were divided into two groups: one group received a high dose (5000 PFU) and the other a low dose (500 PFU) of the vaccine at 1 day of age, with a non-vaccinated group serving as the control. Vaccine viral copy numbers in the spleen and feather tips were detected by quantitative PCR (qPCR) at different days post-vaccination (dpv) (3, 5, 7, 11, and 14 dpv). Meanwhile, a challenge trial was conducted where chickens were challenged with the very virulent Md5 strain (1000 PFU/bird) at 5 dpv and observed until 70 days of age. Results from the vaccination-only experiment revealed that viral replication in the spleen was detectable in 100% of chickens as early as 3 dpv, reaching its peak at 5 dpv, with the high-dose group exhibiting significantly higher viral loads than the low-dose group. In feather tips, replication was detectable in 100% of chickens by 5 dpv and peaked at 7 dpv, but no significant difference was observed between the two dose groups. The unvaccinated control group exhibited 100% mortality with characteristic gross and histopathological lesions of Marek’s disease. In stark contrast, both vaccinated groups (high and low dose) demonstrated 100% survival until the end of the observation period (70 days). No clinical signs or pathological abnormalities were observed in these groups. Furthermore, vaccination with SC9-1 did not adversely impact growth performance and the development of major immune organs, even following subsequent Md5 challenge. The results indicated that a higher initial vaccination dose of the SC9-1 vaccine was associated with elevated peak early in vivo replication level, whereas vaccination dose may not govern viral maturation and shedding levels of SC9-1 in feather-tip tissues. However, peak replication level was not a direct determinant of final protective efficacy. Notably, even the lowest tested dose (500 PFU) afforded full protection against early challenge with a very virulent MDV strain. Collectively, these observations contribute to our understanding of dose-dependent protection induced by gene-deleted MD vaccines and inform rational vaccination strategies.",
  "abstract_shown": true,
  "affiliations": [
    "Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100089, China"
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 8,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Rujun Ye"
    },
    {
      "affs": [
        0
      ],
      "name": "Ruihan Shi"
    },
    {
      "affs": [
        0
      ],
      "name": "Haijun Jiang"
    },
    {
      "affs": [
        0
      ],
      "name": "Chang Liu"
    },
    {
      "affs": [
        0
      ],
      "name": "Mengzhu Dong"
    },
    {
      "affs": [
        0
      ],
      "name": "Hairong Tian"
    },
    {
      "affs": [
        0
      ],
      "name": "Tingwen Zheng"
    },
    {
      "affs": [
        0
      ],
      "name": "Yu Zhou"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/27szgrbwvz9m6.bib",
  "cited_by": 0,
  "doi": "10.3390/v18101052",
  "fulltext_url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13709888/?tool=EBI",
  "id": "27szgrbwvz9m6",
  "issns": [
    "1999-4915"
  ],
  "landing_url": "https://europepmc.org/article/PMC/PMC13709888",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "lcc",
      "QR1-502"
    ],
    [
      "openalex",
      "1103|Animal Virus Infections Studies"
    ]
  ],
  "openalex": "W7214043937",
  "pdf_url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13709888/pdf/?tool=EBI",
  "pmcid": "PMC13709888",
  "pmid": null,
  "published": "2026-09-01",
  "publisher": "MDPI AG",
  "ris": "https://research.draconitic.com/paper/27szgrbwvz9m6.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:21:51Z",
      "native_id": "PMC:PMC13709888",
      "source": "europepmc",
      "url": "https://europepmc.org/article/PMC/PMC13709888"
    },
    {
      "first_seen": "2026-10-31T14:21:37Z",
      "native_id": "0aed75b00934468c983fb0c130ea51ec",
      "source": "doaj",
      "url": "https://doi.org/10.3390/v18101052"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "openalex:1103|Animal Virus Infections Studies",
      "subfield": "zoology-behaviour"
    }
  ],
  "title": "Immunization Dose-Dependent In Vivo Replication Kinetics and Protective Efficacy of the Gene-Deleted Marek’s Disease Vaccine SC9-1",
  "title_text": "Immunization Dose-Dependent In Vivo Replication Kinetics and Protective Efficacy of the Gene-Deleted Marek’s Disease Vaccine SC9-1",
  "type": "peer-reviewed",
  "updated_at": "2026-10-31T14:21:37Z",
  "url": "https://research.draconitic.com/paper/27szgrbwvz9m6",
  "venue": "Viruses",
  "versions": []
}