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Infectious Bronchitis R134A_00_1 First reported by Schalk & Hawn in 1931 in North Dakota (USA) in young chicks showing respiratory signs Distribution:

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Presentation on theme: "Infectious Bronchitis R134A_00_1 First reported by Schalk & Hawn in 1931 in North Dakota (USA) in young chicks showing respiratory signs Distribution:"— Presentation transcript:

1 Infectious Bronchitis R134A_00_1 First reported by Schalk & Hawn in 1931 in North Dakota (USA) in young chicks showing respiratory signs Distribution: Worldwide Transmission: Horizontal, direct contact Incubation period: hours. Infectious Bronchitis

2 R134A_00_2 Agent: Coronavirus (RAN) Host: Chickens of all ages Affects: respiratory tract uro-genital tract * The virus can be isolated from different organs up to ± 50 d.p.i. Infectious Bronchitis

3 R134A_00_3 Young birds: respiratory signs sneezing, coughing, nasal discharge. Mortality may reach 30%, especially in combination with secondary infections (E. coli, M. gallisepticum). Adult birds: respiratory signs egg drops alteration in the internal and external quality of eggs (misshapen and soft eggs, watery albumen). Infectious Bronchitis Pathogenesis:

4 Infectious Bronchitis R134A_00_4 Why is IB still a problem? Highly infectious Persistent in the birds Fast dissemination RNA virus - mutations - recombinations Causes different diseases Many different serotypes ?

5 Infectious Bronchitis R134A_00_5 Ciliostasis Test Tool to measure the effect of a virus on the tracheal mucosa The tracheal mucosa represents a mechanic barrier against foreign particles in the respiratory tract (muco-ciliar apparatus) Consists of motile structures (cilia) and secretory cells (Goblet cells). They trap and eliminate foreign particles (ex. dust and bacteria). Tracheal rings of vaccinated and/or challenged birds are prepared and observed under the microscope.

6 Infectious Bronchitis R134A_00_6 ריסים (( CILIAבעלי פעילות במצב תקין

7 Infectious Bronchitis R134A_00_7 ריסים (( CILIAבמצב פגוע

8 Infectious Bronchitis R134A_00_8 Ciliostasis test 10 tracheal rings3 x top 4 x middle 3 x bottom Results0 = 100% cilia moving 1 = 75% cilia moving 2 = 50% cilia moving 3 = 25% cilia moving 4 = 100% cilia moving

9 Infectious Bronchitis R134A_00_9 New serotypes of IBV can emerge as a result of few aminoacid changes in the S1 part of the spike genome of the virus Antigenic variation

10 Infectious Bronchitis R134A_00_10 Model of the structure of the S protein on the surface of the virus S1 S2 Virion membrane (Cavanagh, 1983)

11 Infectious Bronchitis R134A_00_11 Cross protection against IB viruses belonging to other serotypes may be due to the fact that most of the virus genome remains unchanged From a practical point of view it is therefore more relevant to think in terms of protectotypes rather than serotypes There are occasions when existing IB vaccines do not provide adequate protection against newly emerging serotypes With the continual emergence of new serotypes of IBV it seems prudent to evaluate the level of cross protection obtained by the use of currently available vaccines. Cross protection

12 Infectious Bronchitis R134A_00_12 Cross protection studies

13 Infectious Bronchitis R134A_00_13 4 groups (10 SPF birds) 1Massachusetts (Ma5) at 1 day 24/91 at 14 days 3Massachusetts (Ma5) at 1 day & 4/91 at 14 days 4Not vaccinated Reared in isolators Experimental design

14 Infectious Bronchitis R134A_00_14 Challenged with different field isolates 5 weeks of age by eye drop (0.1 ml) Challenge dose: log CD 50 Ciliostasis test 5 to 7 days p. challenge in all experiments, groups vaccinated and challenged with homologous virus were included Challenge

15 Infectious Bronchitis R134A_00_15 Example of results Maximum index = 40 Vaccine A: - - No protection Vaccine B: - - Good protection Ciliostasis Index

16 Infectious Bronchitis R134A_00_16 Protection against: Arkansas Average ciliostasis index Vaccines used

17 Infectious Bronchitis R134A_00_17 Protection against: Brazil Average ciliostasis index Vaccines used

18 Infectious Bronchitis R134A_00_18 Protection against: Honduras Average ciliostasis index Vaccines used

19 Infectious Bronchitis R134A_00_19 Protection against: South Africa (890/80) Average ciliostasis index Vaccines used

20 Infectious Bronchitis R134A_00_20 Protection against: Taiwan (A1121) Average ciliostasis index Vaccines used

21 Infectious Bronchitis R134A_00_21 Protection against: Holland (D274) Average ciliostasis index Vaccines used

22 Infectious Bronchitis R134A_00_22 Protection against: Holland (D1466) Average ciliostasis index Vaccines used

23 Infectious Bronchitis R134A_00_23 Conclusions The increasing prevalence of new serotypes creates difficulties in the design of adequate vaccination programs against IB It is undesirable and not always necessary to consider developing new live vaccines for each new serotype

24 Infectious Bronchitis R134A_00_24 Conclusions The concept of protectotypes is more relevant from a practical point of view The use of IB vaccines belonging to different serotypes may broaden the protection against a wide variety of antigenically different IBVs


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