Infectious bursal disease (IBD) in chickens, caused by infectious bursal disease virus (IBDV), is an acute, contact-transmissible disease primarily affecting 3- to 6-week-old chicks, leading to severe immunosuppression. In recent years, novel variant IBDV strains (nVarIBDV) have become widespread in China, with traditional vaccines showing limited efficacy. Based on 2025 surveillance data (from Qingdao Yibang Assurance Center and other institutions), WIXBIO addresses the “variable” (variant strain prevalence) and “constant” (environmental resistance, early infection risks) characteristics of IBDV, presenting comprehensive vaccine immunization and field control strategies, recommending the WIXBIO Trivalent IBD Vaccine to establish an effective control system.
1. IBDV Characteristics Analysis
1.1 Variable: Viral Evolution Trends
- Evolutionary History: Evolved from classic virulent strains and very virulent IBDV (vvIBDV) to the currently dominant novel variant strains (nVarIBDV, A2dB1 genotype) and a minority of classic strains.
- 2025 Prevalence: Increased IBDV detection rates in white-feather broilers, young breeder chickens, and layer flocks, reported across 15 provinces (Northeast, East, and South China), with disease onset expanding to 15-35 days of age.
- Clinical Changes: Variant strains exhibit milder symptoms (primarily bursal swelling or atrophy) but induce more severe immunosuppression, reducing the efficacy of H5/H7 avian influenza and Newcastle disease vaccines by 30-40%.
1.2 Constant: Environmental Resistance and Risks
- Resistance: 외피가 없는 바이러스로, pH 2, 50°C 열 및 소독제(예: 4급 암모늄 화합물)에 매우 강하며, 계사에서 최대 4개월까지 생존합니다.
- 조기 감염 위험: 더 이른 시기의 감염(특히 14일 미만)은 파브리시우스낭에서 B 림프구 손실을 더 크게 일으켜 심각한 면역억제를 초래합니다. 2주 이내의 감염은 종종 간과됩니다.
2. Core Control Strategies
IBDV의 특성을 고려할 때 효과적인 방제는 다음 세 가지 필수 조치에 달려 있습니다:
- 높은 모체 항체 수준: 처음 15일 이내의 조기 감염을 차단합니다.
- 철저한 생물보안: 야생형 바이러스에 대한 노출을 줄입니다.
- 표적 예방접종: 중·후기 단계의 계군을 보호하려면 WIXBIO 3가 IBD 백신을 사용하십시오.
3. Field Control Measures
3.1 Selection of Chicks with High Maternal Antibodies
- 공급원: 2~3회 접종한 종계 계군(최소 2회는 불활화 nVarIBDV 백신, 예: A2dB1주)에서 병아리를 선택하여 난황을 통해 높은 항체 수준을 제공합니다.
- 효능: 모체 항체 역가 ≥1:1000은 병아리를 14~21일 동안 보호하여 조기 감염률을 50%만큼 감소시킵니다.
- 사례 연구: 높은 모체 항체를 가진 병아리를 사용한 한 산란계 농장에서는 15일 이내에 IBDV 감염률이 20%에서 5%로 감소했습니다.
3.2 Consistent Biosecurity Measures
- 세척 및 소독:
- 해당 배치가 끝난 후 분변과 사료 잔여물을 철저히 제거하십시오. 1% 과산화아세트산 또는 5% 모노퍼설페이트 칼륨 분말 스프레이로 소독하고, 3% 포름알데히드 훈증(24시간, 20 g/m³)을 병행하십시오.
- 휴지기: 배치 사이에 7~14일의 휴지기를 유지하여 잔존 바이러스를 제거합니다.
- 인력 및 장비 관리:
- 인력은 샤워 후 멸균복(121°C에서 15분간 고압멸균)으로 갈아입어야 합니다. 장비(예: 오리 그물)는 0.5% 글루타르알데하이드에 30분간 담가야 합니다.
- 차량과 수하물은 입구에서 자외선으로 소독합니다(≥30분, 강도 >70 μW/cm²).
- 환경 최적화: 야생 바이러스의 생존을 줄이기 위해 계사의 환기(암모니아 수준 <10 ppm)와 습도(50-70%)를 유지하십시오.
- 효능: A broiler farm implementing 3-4 cycles of biosecurity measures reduced IBDV detection rates from 15% to 2%.
3.3 Targeted Use of WIXBIO Trivalent IBD Vaccine
- Product Features: The WIXBIO Trivalent IBD Vaccine targets classic strains, vvIBDV, and nVarIBDV (A2dB1 genotype), incorporating recombinant VP2 subunits for broad-spectrum protection.
- Immunization Schedule:
- 1-7 Days of Age: Administer WIXBIO Trivalent Inactivated Vaccine, 0.3-0.5 mL per bird, via intramuscular (chest) or subcutaneous (neck) injection, pre-warmed to 25-30°C (30 minutes in 40°C water bath), suitable for chicks with high maternal antibodies.
- Regions with Variable Maternal Antibodies: Booster with WIXBIO attenuated live vaccine (e.g., B87 strain) after 14 days, 0.1-0.2 mL per bird, to minimize maternal antibody interference.
- Mid-to-Late Stage Protection:
- Administer a booster of WIXBIO Trivalent Inactivated Vaccine at 21-28 days to enhance long-term immunity.
- Protection rates reach 85-90%; in 2025, East China pilot farms achieved an average antibody titer of 1:256.
- 사례 연구: A Henan farm using WIXBIO Trivalent Vaccine and 7-day fallow disinfection reduced IBDV infection rates from 10% to 1%.
4. Immunization Protocols
- 보관: Refrigerate at 2-8°C; do not freeze. Use cold-chain transport (4°C).
- 예열: Warm in a 40°C water bath for 30 minutes, shaking every 5 minutes to ensure a temperature of 25-30°C.
- 주사 접종: Ensure accurate single-dose administration, with a missed dose rate <1% and leakage/bleeding rate <2%; re-administer if necessary.
- Record-Keeping: Complete the “Immunization Record Form”; collect 20-30 serum samples 21 days post-vaccination for ELISA testing (target titer ≥1:128).
5. Special Recommendations for Variant IBDV Strains
- Sample Monitoring: Per Guidelines for Poultry Disease Sample Collection and Submission, collect bursa of Fabricius (1-2 g/bird) within 3 days of disease onset for RT-PCR detection of VP2 HVR (222T, 318D mutations) to assess wild virus pressure.
- Vaccine Adjustment: If antibody titers are <1:64, prioritize IBD Vaccine, optimized using 동물세포 현탁배양 기술.
- Enhanced Biosecurity: Disinfect equipment with 0.5% glutaraldehyde before and after immunization to prevent transmission of variant strains.
6. 사례 연구
- Success Case: A broiler farm that adopted WIXBIO Trivalent Vaccine, utilized high maternal antibody chicks, and implemented biosecurity measures reduced IBDV infection rates from 10% to 1%, resulting in a 90% reduction in economic losses.
- Failure Case: A farm neglecting biosecurity and equipment disinfection experienced variant IBDV spread, with mortality rising to 8%.
7. Conclusion and Outlook
Effective IBD control requires a three-pronged approach: high maternal antibodies, stringent biosecurity, and the WIXBIO Trivalent IBD Vaccine. 2025 surveillance indicates an increasing prevalence of nVarIBDV, with heightened risks of traditional vaccine failure. Farms should integrate molecular diagnostics (RT-PCR), standardized operating procedures (SOPs), and WIXBIO’s advanced production technology while strengthening biosecurity to minimize immunosuppression and economic losses.
참고문헌:
- Fan L, et al. Novel variant infectious bursal disease virus suppresses Newcastle disease vaccination. Veterinary Microbiology, 2020.
- OIE, 육상동물 진단검사 매뉴얼, 2023.
- WIXBIO, Trivalent IBD Vaccine Development Report, 2025.
