WO2008121958A1

WO2008121958A1 - Use of prrsv vaccines to reduce pcv2 viremia

Info

Publication number: WO2008121958A1
Application number: PCT/US2008/058898
Authority: WO
Inventors: Wayne Chittick; Marika Genzow
Original assignee: Boehringer Ingelheim Vetmedica, Inc.
Priority date: 2007-04-02
Filing date: 2008-03-31
Publication date: 2008-10-09

Abstract

Methods and compositions for the prophylaxis, prevention, amelioration, reduction in severity of, reduction in the incidence of, and/or treatment of porcine circovirus associated diseases (PCVAD) are provided Preferred compositions include porcine reproductive and respiratory syndrome virus antigenic material Such compositions can be administered in any conventional manner, whereby such administration leads to the prophylaxis, prevention, amelioration, reduction in severity of, reduction in the incidence of, and/or treatment of porcine circovirus associated diseases (PCVAD) prophylaxis, prevention, amelioration, reduction in severity of, reduction in the incidence of, and/or treatment of porcine circovirus associated diseases (PCVAD)

Description

USE OF PRRSV VACCINES TO REDUCE PCV2 VIREMIA

RELATED APPLICATIONS

This application claims the priority benefit of U S Serial No 60/909,607, filed April 2, 2007, the teachings and content of which is hereby incorporated by reference in its entirety

BACKGROUND OF THE INVENTION

TECHNICAL FIELD The present invention belongs to the field of vaccines against infectious diseases, such as diseases associated with porcine circovirus type 2 infection (PCV2) More particularly, it relates to vaccines against porcine reproductive and respiratory syndrome virus (PRRSV), and uses thereof

BACKGROUND INFORMATION

Porcine circovirus type 2 (PCV2) is a small (17 -22 nm in diameter), icosahedral, non- enveloped DNA virus, which contains a single-stranded circular genome PCV2 shares approximately 80% sequence identity with porcine circovirus type 1 (PCV1) However in contrast with PCV1 , which is generally non-virulent, PCV2 has emerged as a major contributor to disease and mortality, with reports of disease associated with this virus reported around the globe (Chae, Veterinary Journal (2005), 169(3), 326-336) Porcine circovirus associated diseases (PCVAD) is a relatively new term for a variety of swine diseases associated with PCV2 infection PCVAD can be subclinical or can include one or more of the following clinical manifestations concurrently multisystemic disease with weight loss (also known as postweaning multisystemic wasting syndrome, PMWS), high mortality (doubling of historical mortality rate without introduction of a new known pathogen), respiratory disease, including dyspnoea or pneumonia, porcine respiratory disease complex (PRDC), porcine dermatitis and nephropathy syndrome (PDNS), enteritis or enteric signs including diarrhoea and weight loss, reproductive disorders including abortions stillbirths and fetal mummification (with presence of fetal myocarditis associated with PCV2 antigen in lesions) These PCV2-assocιated diseases are rapidly becoming a major threat to the health of swine in the United States and in other countries Thus, development of vaccines against PCV2 infection is of interest and has been reported in the art (WO 2007028823, WO 2006132605 WO 2006132598, WO 2006113373, WO 2006072065, WO 03/49703, WO 01/16330, WO 00/77188, WO 00/77216, WO 00/01409, WO 99/29717, WO 99/29871 , WO 99/18214, US 6,703,023) PCV2 vaccines are now also commercially available (Ingelvac® CircoFLEX™, Boehπnger lngelheim Vetmedica Inc, St Joseph, MO, USA, CircoVac®, Menal SAS, Lyon, France, Suvaxyn® PCV2 One Dose, Fort Dodge Animal Health, Overland Park, Kansas)

Studies have shown that clinically sick pigs have significantly elevated duration and magnitude of viremia, usually higher than 1 0 x 10⁷ PCV2 genomes per ml_ of serum Therefore, the quantification of PCV2 in serum may be a method by which accurate identification of PCVAD pigs is accomplished ( Method of qPCR Brunborg et al (2004), J Virol Meth 122, 171-178) Literature also suggests that controlling co-factors in PCVAD is essential for the management of the disease (Allan et al (2000), Vet Rec 170-171)

PCVAD may be accompanied by a variety of concurrent viral or bacterial infections, inter aha infection with porcine reproductive and respiratory syndrome virus (PRRSV) PRRSV is a (+)stranded ssRNA virus belonging to the family of arteriviridae The virus exists as two genotypes referred to as "US" and "EU" type, which share about 50% sequence homology (Dea S et al (2000) Arch Virol 145 659-88), and which can be also distinguished by their immunological properties

Isolation of PRRSV and manufacture of vaccines have been described in a number of publications (WO 92/21375 , WO 93/06211 , WO93/03760, WO 93/07898, WO 93/14196, WO 94/18311 , WO 96/36356, WO 96/40932 ,WO 97/00696, WO 97/27288, WO 97/31651 , WO 99/38582, WO 99/39582, WO 00/065032, WO 06/055331 , EP 0 676 467, EP 0 732 340 EP 0 835 930, DE 4 432 338) PRRS vaccines are also commercially available (Ingelvac® PRRS MLV, Boehπnger lngelheim Vetmedica GmbH, lngelheim, Germany, Ingelvac® PRRS KV and Ingelvac® PRRS ATP, Boehπnger lngelheim Vetmedica Inc, St Joseph/MO, USA, and Porcilis^® PRRS, Intervet Deutschland GmbH, Unterschleiβheim, Germany) Furthermore, approaches have been reported wherein constructs or compositions may comprise antigens or components of both PCV2 and PRRSV (WO 03/062407, KR2006019886 , CN1800375, EP1281760) Porcine circovirus type 2 infection has also been reported to decrease the efficacy of a modified live porcine reproductive and respiratory syndrome virus vaccine (Opπessnig et al , Clinical and Vaccine Immunology (2006), 13(8), 923-929)

BRIEF SUMMARY OF THE INVENTION

The present invention is related to new uses of PRRS vaccines

In particular, it relates to the use of vaccines against PRRSV for the prophylaxis, prevention, amelioration, or treatment of diseases associated with porcine circovirus type 2 infection, in particular PCVAD In such embodiments, the administration of PRRSV vaccines or immunogenic compositions reduces the incidence of, or seventy of, diseases, clinical signs, or symptoms associated with PCV2 infection

In one aspect the invention concerns the use of an immunogenic composition comprising antigenic material of porcine reproductive and respiratory syndrome virus (PRRSV) for the prophylaxis, prevention, amelioration reduction in the incidence of, or severity of or treatment of porcine circovirus associated diseases (PCVAD)

In another aspect, the present invention relates to the use of an immunogenic composition comprising antigenic material of porcine reproductive and respiratory syndrome virus (PRRSV) to decrease the duration or magnitude of viremia of porcine circovirus type 2 (PCV2) in PCV2-ιnfected subjects in particular pigs

The teachings and content of all references cited herein are hereby incorporated by reference in their entireties

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to the use of vaccines against PRRS for the prophylaxis, prevention, amelioration, or treatment of diseases associated with porcine circovirus type 2 infection in particular PCVAD

In one aspect the invention concerns the use of an immunogenic composition comprising antigenic material of porcine reproductive and respiratory syndrome Virus (PRRSV) for the prophylaxis, prevention, amelioration, or treatment of porcine circovirus associated diseases (PCVAD)

An "immunogenic composition ' refers to a composition of matter that comprises at least one antigen which has the capability to elicit an immunological response in the subject to which it is administered Such an immune response can be a cellular and/ or antibody- mediated to the antigen comprised in the composition A "vaccine" is generally referred to as a pharmaceutical composition intended to elicit an immune response with the aim to establish full or partial immunity to disease, or at least some degree of protection, in particular against infective disease Usually, an immunological response includes but is not limited to one or more of the following effects the production or activation of one or more of the following immune system components antibodies, B cells, helper T cells, suppressor T cells, cytotoxic T cells and/or yd T cells directed specifically to an antigen or antigens included in the composition or vaccine of interest Preferably, the host will display either a therapeutic or protective immunological response such that resistance to new infection will be enhanced and/or the clinical severity of the disease reduced Such protection will be demonstrated by any one or more of the following indicators a reduction or lack of symptoms normally displayed by an infected host, a quicker recovery time, a lowered viral titer (viral load) or a shorter viremia in the infected host

In this context an antigen is a molecule that can stimulate an immune response 'Antigenic material" of porcine reproductive and respiratory syndrome virus (PRRSV) is material comprising one or more antigens derived from PRRS virus The antigenic material of PRRSV may comprise complete viral particles, either live (being able to replicate in the host) or inactivated (killed), or fractions and subunits thereof In another embodiment, it may comprise genetic information of PRRSV, optionally in combination with genetic information of other pathogenic organisms, carried by a vector, wherein the genetic information is translated into antigenic polypeptides in the host after introduction

Manufacture of PRRSV vaccines has been described in a number of publications (WO 92/21375 , WO 93/0621 1 , WO93/03760, WO 93/07898, WO 93/14196, WO 94/18311 , WO 96/36356 WO 96/40932 ,WO 97/00696, WO 97/27288, WO 97/31651 , WO 99/38582 WO 99/39582 WO 00/065032, WO 06/055331 , EP O 676 467, EP O 732 340, EP O 835 930, and DE 4 432 338) Modified live vaccines (MLV) of PRRSV are particularly useful in the context of the present invention A modified live vaccine is characterized by containing live PRRS virus, which can replicate in pigs, but without exertion or exhibition of clinical symptoms of PRRS Additionally, there may be only few and moderate symptoms of the disease A virus with these properties is often called "avirulent " Upon administration, a PRRS MLV induces an immunological response in pigs generally leading to significant protection against subsequent infection with pathogenic PRRS virus Viruses of this type are usually called "attenuated " In some forms, attenuated viruses may be generated form pathogenic viral isolates by repeated passaging in suitable host cells until it exhibits the desired properties (WO 92/21375 WO 93/0621 1 WO93/03760 WO 93/07898 WO 96/36356, EP O 676 467, EP O 732 340, EP O 835 930) Alternatively, attenuated viruses may be generated by genetic reengineering through use of an infectious clone, normally a full-length complementary DNA transcript of the viral genome (WO 98/18933, EP 1 018 557, WO 03/062407, WO 06/007813, Nielsen et al, J Virol 2003, 77 3702-3711) MLV containing attenuated PRRS virus of North American (e g Ingelvac® PRRS MLV, Boehringer lngelheim Vetmedica GmbH, Ingelheim, Germany, Ingelvac® PRRS ATP, Boehringer lngelheim Vetmedica Inc, St Joseph/MO, USA) or European genotype (e g Porcilis^® PRRS, Intervet Deutschland GmbH Unterschleiβheim, Germany) are commercially available Alternatively, inactivated virus may be used as so-called "killed vaccine" (KV) In killed vaccines, the virus is typically inactivated by chemical modification, for example by treatment with formaldehyde or binary ethylenimine, which causes a loss in the ability of the virus to replicate PRRSV KV is also commercially available (Ingelvac® PRRS KV, Boehringer Ingelheim Vetmedica GmbH, lngelheim, Germany)

MLV are typically formulated to allow administration of 10' to 10⁷ viral particles per dose, preferably 10³ to 10⁵ particles per dose, and more preferably 10" to 10⁵ particles per dose (4 0-5 0 !ogio TCID₅₀) KV may be formulated based on a pre-inactivation titre of 10³ to 10¹⁰ viral particles per dose Additionally, the vaccine may comprise a pharmaceutically acceptable carrier for example a physiological salt-solution The vaccine may or may not comprise an adjuvant An example of a suitable adjuvant is α-tocopherol acetate, which can be obtained under the trade name Diluvac Forte* Alternatively, alum-based adjuvants may be used

In one embodiment of the present invention, a vaccine may be presented in the form of a freeze-dπed preparation of the live virus, to be reconstituted with a solvent, to thereby result in a solution for injection Preferred solvents include water, physiological saline, or buffer, or an adjuvanting solvent Additionally, the solvent may contain one or more adjuvants, for example α-tocopherol acetate In a preferred embodiment, the reconstituted vaccine may then be injected into a pig, preferably either intramuscularly or intradermal^ A preferred dosage for intramuscular injection would be a volume of about 2ml and a preferred dosage for intradermal injection would be a volume of about 0 2ml

Some preferred forms of the vaccine of the present invention may comprise, in addition to PRRSV antigenic material, further components active against other porcine viral or bacterial diseases, such as porcine circovirus type 2 or classical swine fever virus (PCT/US2006/62654)

Porcine circovirus associated disease (PCVAD) is a relatively new term describing a variety of swine diseases associated with PCV2 infection PCVAD can be subclinical or include one or more of the following clinical manifestations concurrently multisystemic disease with anorexia or weight loss (also known as postweaning multisystemic wasting syndrome, PMWS), high mortality (doubling of historical mortality rate without introduction of a new known pathogen), respiratory signs including dyspnoea, pneumonia (porcine respiratory disease complex, PRDC) porcine dermatitis and nephropathy syndrome (PDNS), enteritis or enteric signs including diarrhoea and weight loss, reproductive disorders including abortions, stillbirths and fetal mummification, and skin discoloration PCVAD may be accompanied by a variety of concurrent viral or bacterial infections, such as porcine reproductive and respiratory syndrome (PRRS) virus, Mycoplasma hyopneumoniae, the swine influenza virus, Pasteurella multocida, Streptococcus suis, Salmonella sp (salmonellosis), E coll enteritis, Haemophilus parasuis (Glasser's Disease), candidiasis, or Pneumocystis carinii

PCVAD is a broad categorization of multisystemic diseases that can be confirmed by documentation of the following histopathological findings in affected pigs depletion of lymphoid cells in lymphoid tissues of the growing pigs, disseminated granulomatous inflammation in one or more tissues (e g spleen, thymus, intestines, lymph nodes

(sternal, bronchial, inguinal and mesenteric), lung, kidney, liver, tonsil, etc ), detection of

PCV2 within the lesions of growing pigs, and PCV2 associated reproductive disease diagnosis with the presence of PCV2 antigen in fetal myocarditis lesions

In another aspect, the present invention relates to the use of an immunogenic composition comprising antigenic material of porcine reproductive and respiratory syndrome virus (PRRSV) to decrease the duration or magnitude of viremia of porcine circovirus type 2 (PCV2) in PCV2-ιnfected subjects, particularly pigs In a preferred embodiment, treated ptgs are older than 12 weeks of age Preferably, they are between 12 and 24 weeks of age, more preferably between 12 and 16 weeks of age In a preferred embodiment, the subjects to be treated are PRRSV-positive before treatment, as determined by an appropriate diagnostic test, for example, the commercially available HerdChek® PRRS of Idexx, Westbrook, Maine In this context, "viremia" refers to the presence of virus in the blood "Active viremia" refers to the capability of the virus to replicate in blood The presence of PCV2 in the blood can be determined by standard diagnostic analysis, such as quantitative PCR, as described in the examples herein See also for example, Brunborg et al (2004), J Virol Meth 122, 171-178

In another aspect, the present invention is related to a method of reducing the magnitude of PCV2 viremia in PCV2-ιnfected subjects, comprising administering an immunogenic composition to the subject, wherein the immunogenic composition comprises antigenic material of PRRSV

In a further aspect, the present invention relates to a process of manufacture of an immunogenic composition which comprises a PRRSV antigen for the prophylaxis, prevention, amelioration, and/or treatment of porcine circovirus associated diseases (PCVAD) EXAMPLES

The following examples are provided for illustrative purposes only and shall not be used to limit the scope of the invention in any manner Modifications of the invention, in addition to those shown herein, will become apparent to those of skill in the art from the description and examples contained herein All such modifications are intended to fall within the scope of the appended claims

EXAMPLE 1

Material and methods

Fifty-nine herds with confirmed PCVAD were investigated In each herd, 5 pigs were necropsied at each of three periods peak mortality, 3-4 weeks pre-peak mortality, and 5-6 weeks pre-peak mortality In addition, 70 serum samples were collected representing a cross sectional sampling of sow farm (gilts, sows) and weaned pigs (approximately 4, 10, 14, 18 and 22-24 weeks of age) Diagnostic testing of tissues from necropsied pigs was carried out to identify pathogens associated with PCVAD The serum samples were analyzed to identify the presence of concurrent swine pathogens in the flow The qPCR PCV2 protocol utilized a TaqMan-based, real-time PCR, using a standard curve created from serial dilutions of a plasmid encoding the open reading frame 2 (ORF2) of PCV2, to determine the viral load in serum samples (Brunborg et al (2004), J Virol Meth 122, 171- 178) Each herd completed a survey to elucidate housing, management practices, medications, and vaccinations The effects of PRRS vaccination status (yes/no) on qPCR PCV2, were analyzed by means of the Wilcoxon-rank-sum test Results were considered statistically significant if p < 0 05 The null hypothesis was that vaccination against PRRSV would have no impact on qPCR PCV2 results

Results

Pigs of 41 herds were not vaccinated against PRRS, pigs of 13 herds were vaccinated with MLV PRRS vaccines and the vaccination status of 5 herds remained unknown In all vaccinated herds, the PRRS vaccine was administered around weaning The analysis of the surveys identified that peak wasting disease was found between 12 and 16 weeks of age in the majority of cases No peak disease was found before 8 weeks of age There was no significant difference in the time point of peak disease between PRRS vaccinated and unvaccinated herds Based on the Idexx PRRS HerdChek® ELISA 2XR, more than 76% of the weaned animals were negative at weaning, with titres < 0 4 The effect of vaccination against PRRS with a modified live vaccine (Ingelvac® PRRS MLV or Ingelvac® PRRS ATP) on qPCR PCV2 results are presented in table 1

Table 1 Effect of PRRS pig vaccination on PCV2 viral load (qPCR PCV2)

Age in weeks PRRS Vacc No animals Mean rank P

(range) qPCR

4 No 131 79 8 0 2

(3-7) Yes 30 86 2 n s

10 No 109 64 0 0 4

(8-12) Yes 20 70 4 n s

14 No 111 75 1 0.02

(13-16) Yes 30 56 0 ***

18 No 110 74 1 0.04

^• (17-20) Yes 39 57 4 _***

22-24 No 1 10 67 7 0.03

Yes 19 49 5 _*** n s = not significant, ^***= significant (p ≤ 0 05)

As evident from table 1 , vaccination of pigs against PRRS had no effect on qPCR for PCV2 in 4 - 12 week old pigs (p > 0 05) However, vaccination against PRRS resulted in significantly lower qPCR results in animals 13 weeks or older, when compared to non- vaccinated animals Interestingly, those animals vaccinated with PRRS had significantly lower viral loads when peak wasting disease was observed in the herds

Conclusion

Vaccination against PRRS decreases the magnitude of viremia of PCV2 as measured by qPCR in PRRS positive and PCVAD affected herds

Claims

WHAT WE CLAIM

1 Use of an immunogenic composition comprising antigenic material of porcine reproductive and respiratory syndrome virus (PRRSV) for the prophylaxis, prevention, amelioration, reduction in severity of, reduction in the incidence of, and/or treatment of porcine circovirus associated diseases (PCVAD)

2 Use of an immunogenic composition comprising antigenic material of porcine reproductive and respiratory syndrome virus (PRRSV) to decrease the duration or magnitude of viremia of porcine circovirus type 2 (PCV2) in PCV2-ιnfected subjects

3 The use of claims 1 or 2, wherein the subjects are pigs which are of an age of more than 12 weeks

4 The use of any one of claims 1 to 3, wherein the subjects are PRRSV positive before treatment

5 The use of any of claims 1 to 4 wherein the immunogenic composition is a modified live vaccine (MLV), or a killed vaccine (KV)

6 The use of any of claims 1 to 5, wherein the PCAVD is postweaning multisystemic wasting syndrome (PMWS) or porcine respiratory disease complex (PRDC)

7 A method of reducing the duration or magnitude of viremia of PCV2 in PCV2- infected subjects, comprising administering an immunogenic composition to the subject, wherein the immunogenic composition comprises PRRSV antigenic material

8 The method of claim 7, wherein the subjects are pigs which are of an age of more than 12 weeks

9 The method of claim 7, wherein the subjects are PRRSV positive before treatment

10. The method of claim 7, wherein the immunogenic composition is a modified live vaccine (MLV), or a killed vaccine (KV).