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蓝耳病毒在美国的流行状况,诊断及防控

放大字体  缩小字体🕓2022-08-05  来源:🔗养猪职业经理人  💛118
核心提示:作者:美国爱荷华州立大学兽医学院 张建强副教授01关于蓝耳病及蓝耳病毒的背景信息Clinical disease临床疾病Respiratory and sys

作者:美国爱荷华州立大学兽医学院 张建强副教授

01

关于蓝耳病及蓝耳病毒的背景信息

Clinical disease临床疾病

Respiratory and systemic disease呼吸道疾病

Reproductive disorders繁殖障碍

Neurological disorders神经系统障碍

Economic ompact经济影响

PRRS Virus (PRRSV)

2 types : PRRSV-1 (Typ* 1. European) and PRRSV-2 (Type 2, North American)

now 2 species:Betaarterivirus mid 1 and Betaarterivirui suid 2

PRRSV-1

First identify in Europe in 1990s (Prototype strain: Lelystad strain)

First reported in the U.S. in 1992-1993 but whole-genome sequences determined in 1999

Globally, 4 subtypes (only Subtype 1 in the U.S.)

PRRSV-2

First identified in the U.S. in 1990$ (Prototype strain: VR-2332 strain)

RFIP pattern (cutting pattern by Mlul, Hincll, and Socll) commonly used in the North America

ORFS-based genetic classification system

02

蓝耳病毒在美国的流行状况

1、所有年龄段的猪及所有检测的样品类别(2010-2021四个实验室的数据)

可常年检测到蓝耳病;

但有一定的季节性;

在夏天的检出阳性率偏低;

蓝耳病毒可以在各个生产阶段(年龄段)的猪只中检测到;

蓝耳病毒PCR检出阳性率会有波动;

在种猪群里,蓝耳病毒PCR阳性率很低。

2、PRRSV-1 and PRRSV-2

Data from ISU+ UMN + SDSU+ KSU (from 2007 to 2018)

106,392 PRRSV PCR-positive cases

100,818 cases (94.76%) positive for PRRSV-2

2,289 cases (2.15%) positive for PRRSV-1

3,285 cases (3.09%) positive for PRRSV-1 and PRRSV-2

03

蓝耳病毒的诊断方法

1、PRRSV Diagnostics蓝耳病毒诊断

specimens for testing 用于检测和诊断的样品

Pathological and histopathological evaluation 病理及组织病理评佔

Detection of viral nucleic acid, viral antigen, infectious virus 基于核酸,抗原及活病毒的检测

RT-PCR (duplex for Type 1 & Type 2)

Sequencing 测序

Immunohistochemistry 免疫组化

Direct tissue fluorescence antibody test 组织荧光抗体(FA)方法

Virus isolation病毒分离

Action of antibody 抗体检测

Detection of antibody 抗体检测

ELISA (HerdChek-PRRS X3, IDEXX): both Type 1 and Type 2 PRRSVs - Serum, Oral fluid

Indirect fluorescent antibody test (IFA): Serum; could be virus-specific IFA assay 免疫荧光抗体

Virus neutralization test: Serum; could be virus-specific VN test 中和抗体

2、PRRSV Virus Isolation in ZMAC and MARC-145 cells

It is a challenge to isolate PRRSV from oral fluid and processing fluid samples

从口腔液和睾丸/断尾液里分离蓝耳病毒很困难

Preferred specimen types for PRRSV VI: lung > serum > processing fluid and oral fluid

推荐用于分离蓝耳病毒的样品类别:肺组织 > 血清>口腔液和睾丸/断尾液

serum and lung samples: Higher success rate of PRRSV VI in ZMAC than in MARC-145 cells.

When PRRSV VI is Neg in MARC-145 cells, VI attempts in ZMAC cells are recommended

对于肺组织和血清样品,如果蓝耳病毒分离在MARC-145细胞时阴性,建议尝试ZMAC细胞

For cost-effectiveness, it is recommended to conduct PRRSV VI from clinical samples with Ct<30.

建议用 Ct值小于30的肺组织或血清样品做蓝耳病毒分离,以提高分离成功率

Impacts of PRRSV-2 genetic lineages on VI varied

o LI & L8: VI success rate ZMAC > MARC-145

O L5:success rate similar in ZMAC and MARC-145

Not all of the PRRSV islates obtained in ZMAC cells can grow in MARC-145 cells

不是所有的在ZMAC细胞分离出的蓝耳病毒株都能在MARC-145 细胞里生长

3、Is PRRSV in clinical sample and cell culture isolate the sample

995 PRRSV-2 PCR-positive specimens

548 serum, 397 lung,and other 50 sample;

Results can be summarized in three categories

category1: PRRSV-2 strains in clinical samples and MARC-145 and/or ZMAC isolates match each other

category2: Different RFLP (mismatching nucleotides at cutting sites); similar PRRSV-2 in clinical samples and isolates

Category 3:

Similar PRRSV-2 in clinical

04

蓝耳的防控

1、Biosecurity and management

To reduce the probability of introducing PRRSV into negative herds or new PRRSV variants into positive herds

Examples

2.丶Induction of protective immunity

Live virus inoculation (LVI):farm-specific wild-type virus,serum from infected pigs

Autogenous vaccines:killed farm-specific wild-type virus isolate

Commercial killed vaccines

Commercial modified live virus (MLV) vaccines

3、Supplemental prophylactic and therapeutic measures

During an acute outbreak,administer anti-inflammatories to control fever and antibiotics to manage secondary bacterial infections

Ivermectin:effectiveness?

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