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Table 1 Experimental design of the immunization and challenge tests against QX-like IBV strain SD in chickensa.

From: Pathogenic characteristics of a QX-like infectious bronchitis virus strain SD in chickens exposed at different ages and protective efficacy of combining live homologous and heterologous vaccination

Group

No. of chickens

Age (d)

Vaccine

Route

Challenge

Route and dose of challenge

Day 21

Day 35

A

10

1

Ma5b

Oculo-nasally

IBV strain SD

–

Oculo-nasally, 106 EID50/bird, 0.2 mL

B

10

1

LDT3-Ab

Oculo-nasally

IBV strain SD

–

Oculo-nasally, 106 EID50/bird, 0.2 mL

C

10

1

QXb

Oculo-nasally

IBV strain SD

–

Oculo-nasally, 106 EID50/bird, 0.2 mL

D

10

1

Ma5 + H120c

Oculo-nasally

–

–

Oculo-nasally, 106 EID50/bird, 0.2 mL

E

10

1

LDT3-A + H120c

Oculo-nasally

–

IBV strain SD

Oculo-nasally, 106 EID50/bird, 0.2 mL

F

10

1

QX + H120c

Oculo-nasally

–

IBV strain SD

Oculo-nasally, 106 EID50/bird, 0.2 mL

G

10

1

QX + QXd

Oculo-nasally

–

IBV strain SD

Oculo-nasally, 106 EID50/bird, 0.2 mL

H

10

1

PBS

Oculo-nasally

IBV strain SD

–

Oculo-nasally, 106 EID50/bird, 0.2 mL

I

10

1

PBS + PBS

Oculo-nasally

–

IBV strain SD

Oculo-nasally, 106 EID50/bird, 0.2 mL

J

10

1

–

–

–

–

Oculo-nasally, PBS, 0.2 mL

  1. aAll chickens are local egg-producing chickens.
  2. bVaccination at day 1.
  3. cMa5, LDT3-A or QX vaccination at day 1, H120 vaccination at day 21.
  4. dFirst vaccination at day 1, second at day 21.