The document discusses infectious coryza, caused by Haemophilus paragallinarum bacteria. There are two main serotyping schemes for H. paragallinarum - Page and Kume. Page recognizes 3 serovars (A, B, C) that represent distinct immunovars and vaccines for one serovar do not protect against the others within the same serovar. Kume also recognizes 3 serogroups that correspond to Page serovars. Chickens develop varying degrees of natural immunity after infection, with full homologous immunity developing within 2 weeks against the same serovar but also some cross-protection between Page serovars.

1. Infectious Coryza
The Organism

2. Plan of Talk
 Introduction
 The Organism
 Natural Immunity

3. Plan of Talk
 Introduction
 The Organism
 Natural Immunity

4. Introduction
 Early workers identified the causative agent as “Haemophilus
gallinarum,” an organism that required both X (hemin) and V
(NAD) factors for growth in vitro.
 However, from the 1960s to the 1980s, all isolates of the
disease producing agent have been shown to require only V
factor and have been termed Haemophilus paragallinarum.
 V-factor-independent H. paragallinarum isolates have been
encountered in the Republic of South Africa since 1989.

5. Cont. …
 Thus, the causative agent of infectious coryza is regarded as
Haemophilus paragallinarum, an organism that can be either
V-factor dependent or independent.

6. Plan of Talk
 Introduction
 The Organism
 Natural Immunity

7. The Organism
There are two different but related serotyping schemes for H.
paragallinarum have been mainly used:
1. The Page.
2. The Kume.

8. The Organism
Page Serotyping
 The most widely used serotyping scheme for H.
paragallinarum is that described by Page which recognizes 3
serovars (A, B and C).

9. Cont. …
 Some reports have cast doubt on the validity of Page’s
serovar B suggesting that the members of this serovar are
variants of serovars A and C.
 However, it has recently concluded that Page serovar B is true
serovar and that, with the exception of reference 0222,
isolates of serovar B are fully pathogenic.

10. Cont. …
 Page scheme was initially developed by using a plate or slide
agglutination test.
 It recognized 3 serovars, A, B, and C.
 The 3 Page serovars represent distinct “immunovars,”
 Inactivated vaccines based on any one Page serovar provide no
protection against the other two Page serovars.
 It is generally accepted that cross-protection occurs within every one
of Page serovars.

11. The Organism
Kume Serotyping
 The Kume serotyping scheme is an alternative to the Page
scheme.
 This recognizes 3 serogroups which have recently been shown
to correspond to Page serovars A, B and C.
 Minor differences exist and can be detected by the use of
absorbed antisera.

12. Cont. …
 It resulted in a typing scheme that, when initially proposed,
recognized 3 serogroups and 9 serovars.
 Currently the recognized Kume serovars are A-1, A-2, A-3, A-4,
B-1, C-1, C-2, C-3 and C-4.
 Cross-protection between all 4 serovars within both Kume
serogroups A and C have not yet been performed
 Serovars within a Kume serogroup are cross-protective.

13. Plan of Talk
 Introduction
 The Organism
 Natural Immunity

14. Natural Immunity
Chickens that recover from a natural infection of infectious
coryza possess varying degree of immunity.
Homologous immunity develops 2 weeks after initial
exposure (Sato and Shifrine, 1964).
Homologous immunity as well as some degree of
heterologous immunity that extends across the Page
serovars (Rimler et al. 1977).