BACKGROUND

The present application is directed to polypeptides useful in preparing a vaccine against necrotic enteritis in poultry. More specifically, the present application is directed to aClostridium perfringenspilus polypeptide useful in preparing a vaccine against necrotic enteritis related toClostridium perfringensinfection in poultry.

Necrotic enteritis is an intestinal disease of poultry such as broiler chickens, that in 2015 was estimated to cost the poultry industry $US 6 billion in losses. Necrotic enteritis is caused primarily by certain Type A strains ofClostridium perfringensthat produce the NetB pore-forming toxin, which overgrow and adhere to the intestinal mucosa, eventually causing the characteristic lesions of the disease.Clostridium perfringensis a normal inhabitant of the intestinal tract, and typically only those strains that carry the NetB toxin can cause necrotic enteritis. Necrotic enteritis is primarily controlled by application of in-feed antibiotics, a practice that is increasingly discouraged due to the potential spread of antimicrobial resistance, and which is currently being phased out of production in some countries. It is therefore important, from both a financial and public health perspective, to find alternative approaches to control necrotic enteritis, such as the development of a vaccine.

AClostridium perfringensadherence genetic locus (VR-10B) has been recently identified through its association with NetB-positive strains (Lepp D, Gong J, Songer J G, Boerlin P, Parreira V R, Prescott J F. 2013. Identification of Accessory Genome Regions in PoultryClostridium perfringensIsolates Carrying the netB Plasmid. Journal of Bacteriology 195: 1152-1166). The identified genetic locus was found to be present in 87% of netB-positive and 42% of netB-negative isolates, of 54 poultry isolates examined. This genetic locus (subsequently renamed the collagen adhesion (CA) locus) was later shown to be involved in collagen binding, and required for necrotic enteritis pathogenesis (Wade B, Keyburn A L, Haring V, Ford M, Rood J I, Moore R J: The adherent abilities ofClostridium perfringensstrains are critical for the pathogenesis of avian necrotic enteritis. Vet Microbiol 2016, 197: 53-61; Wade B, Keyburn A L, Seemann T, Rood J I, Moore R J: Binding ofClostridium perfringensto collagen correlates with the ability to cause necrotic enteritis in chickens. Vet Microbiol 2015, 180: 299-303.).

A number ofClostridium perfringensproteins have previously been evaluated as vaccine candidates. However, these proteins offer at best partial protection against necrotic enteritis. In addition, many of these proteins are not specific to necrotic enteritis-causing strains, and are not known to play a role in necrotic enteritis pathogenesis. Therefore, it is desirable to identify alternativeClostridium perfringenspolypeptides which may be candidates for producing a vaccine against necrotic enteritis.

SUMMARY

One aspect of the present invention provides an isolatedClostridium perfringenspilus polypeptide. In another aspect, the present invention provides an immunogenic polypeptide selected from an isolatedClostridium perfringenspilus polypeptide, a variant of the pilus polypeptide; a fragment of the pilus polypeptide; and a fragment of the variant, wherein the pilus polypeptide, the variant, the fragment of the polypeptide and the fragment of the variant are immunogenic in poultry. In at least one embodiment, the pilus polypeptide is a CnaA polypeptide. In at least one embodiment, the pilus polypeptide is a FimA polypeptide. In at least one embodiment, the pilus polypeptide is a FimB polypeptide. In at least one embodiment, the pilus polypeptide is an assembled pilus.

Another aspect of the present invention provides a polynucleotide comprising a sequence encoding an isolatedClostridium perfringenspilus polypeptide or an immunogenic polypeptide as described herein. In another aspect, the present application provides a vector comprising a polynucleotide having a sequence encoding an isolatedClostridium perfringenspilus polypeptide or an immunogenic polypeptide as described herein, wherein the vector is configured for expression of the isolatedClostridium perfringenspilus polypeptide or immunogenic polypeptide in a host cell.

In another aspect, the present invention provides a vaccine for the treatment or prevention of necrotic enteritis in poultry, wherein the vaccine comprises an immunogenic polypeptide as described herein. In another aspect, the present application provides a vaccine for the treatment or prevention ofClostridium perfringensinfection in poultry, wherein the vaccine comprises an immunogenic polypeptide as described herein.

In another aspect, the present invention provides the use of an immunogenic polypeptide as described herein in the preparation of a medicament for the treatment or prevention of necrotic enteritis in poultry or for the treatment or prevention ofClostridium perfringensinfection in poultry.

In another aspect, the present invention provides a method of treatment or prevention of necrotic enteritis in poultry or for the treatment or prevention ofClostridium perfringensinfection in poultry, the method comprising administering an effective amount of an immunogenic polypeptide as described herein, or a vaccine thereof, to the poultry.

In another aspect, the present invention provides the use of an immunogenic polypeptide as described herein as a vaccine for the treatment or prevention of necrotic enteritis in poultry or for the treatment or prevention ofClostridium perfringensinfection in poultry.

A further aspect of the present invention provides an antibody which binds selectively to an immunogenic polypeptide as described herein. In another aspect, the present invention provides a method of detectingClostridium perfringensinfection in poultry by obtaining a biological sample from the poultry and detecting in the biological sample the presence of an antibody which binds selectively to an immunogenic polypeptide as described herein. Yet another aspect of the present invention provides a method of detecting an immunogenic polypeptide as described herein comprising exposing the immunogenic polypeptide to an antibody which binds selectively to the immunogenic polypeptide and detecting binding of the immunogenic polypeptide to the antibody.

