PCV2 Mycoplasma hyopneumoniae immunogenic compositions and methods of producing such compositions

Abstract

Multivalent combination vaccines are provided which include an immunological agent effective for reducing the incidence of or lessening the severity of M. hyo infection, preferably M. hyo bacterin, or an immunogenic composition comprising M. hyo bacterin, and at least one immunogenic active component of another disease-causing organism in swine, preferably PCV2 wherein the preferred PCV2 antigen for such a multivalent vaccine is PCV2 ORF 2 protein.

Claims

1. A method for eliciting a protective immune response in a pig against Mycoplasma hyopneumoniae (M. hyo) comprising administering to said pig a single dose of an immunogenic composition which comprises porcine circovirus type 2 antigen and M. hyo antigen, wherein the amount of the M. hyo antigen per a single dose is equivalent to 40-fold the amount of a determined relative potency value in mice, wherein the relative potency value in mice for M. hyo is determined by the steps: (a) making serial dilutions of a composition containing an unknown amount M. hyo antigen to be determined to form a plurality of serial dilution groups with each member of each group having the same serial dilution; (b) dividing a plurality of mice into groups to form a number of mice groups, wherein the number of mice groups is the same as the number of serial dilution groups and each mice group contains a plurality of mice; (c) administering a single dose of each serial dilution group containing said M. hyo antigen of step (a) to each mouse in a mice group such that each mouse in a mice group receives the same serial dilution and each mice group receives a different serial dilution; (d) taking a biological sample from each mouse in each mice group for each serial dilution group after a period of 21 days; (e) detecting M. hyo specific antibodies present in the biological samples of step (d); (f) determining the relative potency value of the M. hyo composition, wherein the relative potency is equal to the maximal serial dilution at which 100% of mice receiving said single dose of M. hyo antigen of step (c) develop a detectable amount of M. hyo antibodies within 21 days post treatment as detected in an M. hyo specific antibody detection assay of step (e); (g) calculating the amount of M. hyo antigen to administer to a pig by multiplying the maximal serial dilution amount as determined in step (e) by a factor of 40; and (h) administering to said pig an immunogenic composition which comprises porcine circovirus type 2 antigen and M. hyo antigen, wherein the amount of the M. hyo antigen per a single dose is equivalent to the calculation of step (g).

2. The method of claim 1, wherein the amount of porcine circovirus type 2 antigen per a single dose is equivalent to 10-fold the amount of a determined relative potency (RP) value in mice, wherein the RP value in mice for porcine circovirus type 2 antigen is determined by the steps: (a) making serial dilutions of a composition containing an unknown amount porcine circovirus type 2 antigen to be determined to form a plurality of serial dilution groups with each member of each group having the same serial dilution; (b) dividing a plurality of mice into groups to form a number of mice groups, wherein the number of mice groups is the same as the number of serial dilution groups and each mice group contains a plurality of mice; (c) administering a single dose of each serial dilution group containing said porcine circovirus type 2 antigen of step (a) each mouse in a mice group such that each mouse in a mice group receives the same serial dilution and each mice group receives a different serial dilution; (d) taking a biological sample from each mouse in each mice group for each serial dilution group of step (c) after a period of 21 days; (e) detecting porcine circovirus type 2 specific antibodies present in the biological samples of step (d); (f) determining the relative potency value of the porcine circovirus type 2 composition, wherein the relative potency is equal to the maximal serial dilution at which 100% of mice receiving said single dose of porcine circovirus type 2 antigen of step (c) develop a detectable amount of porcine circovirus type 2 antibodies within 21 days post treatment as detected in a porcine circovirus type 2 specific antibody detection assay of step (e); (g) calculating the amount of porcine circovirus type 2 antigen to administer to a pig by multiplying the maximal serial dilution amount as determined in step (f) by a factor of 10; and (h) administering to said pig the immunogenic composition which comprises porcine circovirus type 2 antigen and M. hyo antigen, wherein the amount of the porcine circovirus type 2 antigen per a single dose is equivalent to the calculation of step (g).

3. The method according to claim 1, wherein said immunogenic composition further comprises an adjuvant.

4. The method composition according to claim 3, wherein the adjuvant is a carbomer.

5. The method according to claim 1, wherein said immunogenic composition elicits a protective immune response against M. hyo when administered to said pig as a single dose administration.

6. The method according to claim 1, wherein said immunogenic composition elicits a protective immune response against M. hyo and porcine circovirus type 2 when administered to said pig as a single dose administration.

7. The method according to claim 1, wherein the immunogenic composition elicits a duration of immunity against M. hyo and/or porcine circovirus type 2 of at least 130 days when administered to said pig.

8. The method according to claim 7, wherein the immunogenic composition elicits a duration of immunity against M. hyo and/or porcine circovirus type 2 of at least 150 days when administered to said pig.

9. The method according to claim 7, wherein the immunogenic composition elicits a duration of immunity against M. hyo and/or porcine circovirus type 2 of at least 184 days when administered to said pig.

10. The method according to claim 1, wherein the specific antibody detection assay is an ELISA.

11. The method according to claim 2, wherein the specific antibody detection assay for detecting the porcine circovirus type 2 specific antibodies is a modified indirect porcine circovirus (PCV) type 2-based and recombinant capsid protein (ORF2)-based ELISA for the detection of antibodies to PCV.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) The following examples set forth preferred materials and procedures in accordance with the present invention. It is to be understood, however, that these examples are provided by way of illustration only, and nothing therein should be deemed a limitation upon the overall scope of the invention.

Example 1

(2) The study design was set up to evaluate the combination efficacy of PCV2-M. hyo at full and 2 dose, at two different inclusion levels of M. hyo for the combination product and also to demonstrate any interference of the combination product compared to the monovalent M. hyo.

(3) Materials and Methods:

(4) Pigs were divided into 6 groups. All of the challenge groups (Groups 1-5) had around 19 pigs in each group. The control group containing pigs that were not given treatment and were not challenged (Group 6) had 5 pigs in the group. All pigs were necropsied on Day 61 of the study. The Schedule of the Investigation is shown below in Table 1

(5) TABLE-US-00001 TABLE 1 Study Day (approximately) Study Event Before Day 0 ID pigs; Health examination (D0) Before D0 Randomize pigs to one of five groups D-2 All pigs: Collect blood samples; Clinical Assessments D0 All pigs: Clinical Assessments D0 Administer Investigational Veterinary Product 1 (IVP1) to Group 1; Administer Investigational Veterinary Product 2 (IVP2) to Group 2; Administer Investigational Veterinary Product 3 (IVP3) to Group 3; Administer Investigational Veterinary Product 3 (IVP3) to Group 4; Administer Control Product (CP) to Group 5. D1 to D33 All pigs: Clinical Assessments D12 Collect blood samples from all animals. Administer IVP-3 to Group 3; CP administered to Group 5. D32 Move at least the strict control group (Group 6) to a separate room D33 All pigs: Collect blood samples All pigs: Anesthetize; Challenge with virulent M. hyopneumoniae strain 232 D32 to D63 All pigs: Daily clinical observations D47 All pigs: Collect blood samples D61 All pigs: Collect blood samples All pigs: Euthanize; Necropsy; Score lungs; Collect lung samples

(6) This is a vaccination-challenge efficacy study conducted in a minimum of 100 piglets, approximately 216 days of age on Day 0 (D0).

(7) Prior to the start of the study, piglets' sera was drawn and screened for serological status to M. hyopneumoniae and Porcine Reproductive and Respiratory Syndrome virus (PRRSV). Only piglets that were negative for M. hyopneumoniae and PRRSV antibodies in serum were considered for the study. Table 2 gives a summary of the study.

(8) TABLE-US-00002 TABLE 2 Challenge with M. hyopneumoniae Day of Group Number Treatment on D0 Treatment on D12 On D33 Necropsy 1 19 1.0 mL of IVP-1 (50 mL N/A Yes D61 of M. hyo Bacterin) IM in the neck region 2 19 2.0 mL of IVP-2 (100 N/A Yes D61 mL: 50 mL of M. hyo Bacterin and 50 mL of PCV2 vaccine) IM in the neck region 3 19 1.0 mL of IVP-3 (100 1.0 mL of IVP-3 Yes D61 mL: 50 mL of M. hyo (100 mL: 50 mL of M. Bacterin and 50 mL of hyo Bacterin and 50 mL PCV2 vaccine) IM in the of PCV2 vaccine) IM in neck region the neck region 4 19 2.0 mL of IVP-3 (100 N/A Yes D61 mL: 50 mL of M. hyo Bacterin and 50 mL of PCV2 vaccine) IM in the neck region 5 19 2.0 mL of CP (50 mL 1.0 mL of CP (50 mL Yes D61 saline) IM in the neck saline) IM in the neck region region 6 5 N/A N/A N/A D61

(9) IVP-1 (monovalent M. hyo) was serial 273-011B that had a release RP of 1.44 and an RP of 1.22 at 18 months. IVP-2 (PCV2-M. hyo) utilized M. hyo serial 273-011B (RP of 1.22 at 18 months) and PCV2 serial 309-035 (release RP of 1.38) IVP-3 (PCV2-M. hyo) was composed of M. hyo serial 273-010B (release RP 2.8) and PCV2 serial 309-035 (release RP of 1.38)

(10) Prior to D0, all pigs were assigned completely at random to one of six groups. Group 1 consisted of 19 pigs and was assigned to the M. hyo vaccine treatment group (Investigational Veterinary Product-1 (IVP-1)) treated group. Group 2 consisted of 19 pigs and was assigned to a M. hyo-PCV2 vaccine (Investigational Veterinary Product-2 (IVP-2)) treatment group and was administered a 12.0 mL dose on day 0. Group 3 consisted of 19 pigs and was assigned to a M. hyo-PCV2 vaccine treatment group (IVP-3) and was administered a 1.0 mL dose on days 0 & 12. Group 4 consisted of 19 pigs and received a M. hyo-PCV2 vaccine (IVP-3) 12.0 mL on Day 0. Group 5 served as challenge controls and received 2.0 mL of control product on Day 0 and 1.0 mL of control product on Day 12. Group 6 served as strict controls and did not receive any product. Prior to D0, each pig was examined for overall health and had their blood sampled.

(11) On D0, 1) 19 piglets assigned to Group 1 received 1.0 mL of IVP-1 IM; 2) 19 piglets assigned to Group 2 received 2.0 mL of IVP-2 IM; 3) 19 piglets assigned to Group 3 received 1.0 mL of IVP-3 IM on days 0 &12; 4) 19 piglets assigned to Group 4 received 2.0 mL of IVP-3 IM on Day 0; 5) 19 piglets assigned to Group 5 received 2.0 mL of CP IM on Study Day 0 and 1.0 mL IM on Study Day 12; and, 6) 5 piglets assigned to Group 6 did not receive product and served as strict controls.

(12) On Study Day 0, treatments were administered in the right neck region, midway between the base of the ear and the point of the shoulder. On Study Day 12, treatment was administered in the left neck region, midway between the base of the ear and the point of the shoulder. All piglets were observed daily from D1 to D33 for any adverse events and overall health. All piglets were blood sampled on D33. On D33, each pig was challenged intratracheally with 10 ml of virulent M. hyopneumoniae. All pigs were observed daily for any clinical signs of disease from D32 to D61. Blood samples were collected from all pigs on D47 and D61. Blood samples collected prior to IVP administration were tested for M. hyopneumoniae and PRRS serology. Blood samples collected on D12, D33, D47 and D61 were tested for M. hyopneumoniae serology only. On D61, all pigs were euthanized and necropsied. The lungs and trachea were removed and the lungs scored. A sample was removed from each lung and tested by PCR for M. hyopneumoniae DNA. To determine if the study objective was achieved, lung lesion score data from Group 1, 2, 3 and 4 was compared to controls (Group 5) for statistically significant differences. Data from Group 6 was not included in any statistical analysis and was for information purposes only. Other M. hyopneumoniae parameters that were analyzed between Group 1, 2, 3 and 4 and controls (Group 5) included M. hyopneumoniae serology, post-vaccination clinical assessments and post-challenge clinical signs. PCR testing for the presence of M. hyopneumoniae DNA was completed on samples taken from the lungs to demonstrate an effective challenge.

(13) Results and Discussion:

(14) Upon necropsy, lungs were scored. One animal in Group 1 had consolidation and multiple abscesses and one animal in Group two had consolidation plus pleuritis. Statistical analysis was performed both with and without these two animals. As shown below, Group 3 had the lowest lung score of the vaccinated groups, with a score of 2.20. Group 4 had the highest lung score of the vaccinated groups, with a score of 4.19. Both Groups 1 and 2 had a lower lung score when animals 729 and 712, respectively, had been removed, with lung score for Group 1 being 2.13 and 2.56 for Group 2 with the animals removed. Lung scores for all of the vaccinated groups were significantly lower than the lung score of Group 5 (14.27) in which the pigs were challenged and no vaccine was administered.

(15) Lung Scores:

(16) TABLE-US-00003 Average Lung Group Scores 1 5.54 1 (with 729 2.13 removed) 2 3.90 2 (with 712 2.56 removed) 3 2.20 4 4.19 5 14.27 6 0.00

(17) Below is the statistical pairwise comparison summary. This includes analysis both with and without the two animals with conflicting factors.

(18) Results of Pairwise Test-Scores.

(19) TABLE-US-00004 Comparison Wilcoxon Two- P Value Median P Value Two- (Group v. Group) Sample Test Two-Sample Test Sample T Test 1 vs. 5 <0.0001 <0.0001 <0.0001 1 vs. 5 (729 <0.0001 <0.0001 <0.0001 Removed) 2 vs. 5 <0.0001 <0.0001 <0.0001 2 vs. 5 (712 <0.0001 <0.0001 <0.0001 Removed) 3 vs. 5 <0.0001 <0.0001 <0.0001 4 vs. 5 <0.0001 <0.0001 <0.0001 1 vs. 2 0.3707 0.3872 0.3012 1 vs. 2 (712 and 0.1636 0.2931 0.1139 729 Removed) 3 vs. 4 0.0006 0.0005 0.0165 2 vs. 4 0.2196 0.2706 .7767 2 vs. 4 (712 0.1045 0.1511 0.5296 Removed) 1 vs. 3 0.1752 0.1365 0.0247 1 vs. 3 (729 0.6212 0.3629 0.9196 Removed) 1 vs. 4 0.0356 0.0515 0.3785 1 vs. 4 (729 0.0022 0.0135 0.0150 Removed)

(20) All vaccinated groups showed statistically significant results when compared to controls. There were differences between the 2 dose and the 12 ml dose (Groups 3 and 4). These groups had lung scores of 2.2 and 4.19 respectively. There were also differences between the monovalent and the high M. hyo antigen inclusion combo group (Group 1 versus 4). The results of this study provide surprising results that M. hyo in combination with PCV2 can provide an immunogenic effect when administered to pigs, as well as preserve the efficacy of the M. hyo component. Additionally, the results show that a single dose of the composition provides quick, long-lasting immunity. A single dose of this kind requires less time and manual labor and puts less stress on the pigs.

Example 2

(21) This study design was set up to determine the duration of immunity of the combination vaccine.

(22) Materials and Methods:

(23) Pigs were divided into 6 groups. All of the challenge groups (Groups 1-5) had around 19 pigs in each group. The control group containing pigs that were not given treatment and were not challenged (Group 6) had 5 pigs in the group. The Schedule of the Investigation is shown below in Table 3.

(24) TABLE-US-00005 TABLE 3 Challenge with M. Num- Treatment Treatment hyopneumoniae Group ber on D0 on D12 On D33 1 19 1.0 mL of N/A Yes IVP-1 (50 mL of M. hyo Bacterin) IM in the neck region 2 19 2.0 mL of IVP-2 N/A Yes (100 mL: 50 mL of M. hyo Bacterin and 50 mL of PCV2 vaccine) IM in the neck region 3 19 1.0 mL of IVP-3 1.0 mL of IVP-3 Yes (100 mL: 50 mL (100 mL: 50 mL of M. hyo Bacterin of M. hyo Bacterin and 50 mL of and 50 mL PCV2 vaccine) of PCV2 vaccine) IM in the IM in neck region the neck region 4 19 2.0 mL of IVP-3 N/A Yes (100 mL: 50 mL of M. hyo Bacterin and 50 mL of PCV2 vaccine) IM in the neck region 5 19 2.0 mL of CP 1.0 mL of CP Yes (50 mL saline) (50 mL saline) IM in the neck IM in the neck region region 6 5 N/A N/A N/A

(25) The pigs in the challenged groups were challenged on D184 of the study. All piglets were observed daily from D1 to D33 for any adverse events and overall health. All piglets were blood sampled on D33. On D184, each pig was challenged intratracheally with 10 ml of virulent M. hyopneumoniae. All pigs were observed daily for any clinical signs of disease from D32 to D184. Blood samples were collected from all pigs on D47 and D61. Blood samples collected prior to IVP administration were tested for M. hyopneumoniae and PRRS serology. On D184, all pigs were euthanized and necropsied. The lungs and trachea were removed and the lungs scored.

(26) Results and Discussion

(27) After the pigs were necropsied their lungs were removed, and the lungs were observed for lung lesions. The vaccinated groups (Groups 1-4) had an average gross lung pathology of 6.2% (P>0.0023), the challenge control group (Group 5) had an average gross lung pathology of 14.9%, and the strict controls group (Group 6) had an average gross lung pathology of 1.6%. These results are summarized in Table 4 below.

(28) TABLE-US-00006 TABLE 4 Efficacy of INGELVAC MYCOFLEX 26 weeks post-vaccination Treatment Average Gross Lung Group Pathology (% of lung) INGELVAC 6.2% MYCOFLEX (P < 0.0023) Challenge Controls 14.9% Strict Controls 1.6%

(29) The results of this study indicate that the vaccine combination of M. hyo and PCV2 has a long-lasting effect in pigs that is at least 184 days or 26 weeks post vaccination. This is a surprising result given that the combination of M. hyo and PCV2 antigens is a novel combination.

Example 3

(30) This investigation was carried out to determine the amount of interference observed when mixing an antigen of M. hyo with an antigen of PCV2. The study demonstrated that the M. hyo component of the vaccine was still effective in the presence of PCV2.

(31) Materials and Methods

(32) Pigs were 3 weeks5 days of age at vaccination. Group 1 was vaccinated with a single 2 ml dose of M. hyo antigen in the form of a bacterin. Group 2 was vaccinated with a single 2 ml dose of equal amounts of M. hyo antigen and PCV2 antigen. Group 3 was a challenge control group and Group 4 was a strict control group. Groups 1-3 were subsequently challenged on D33 with a virulent M. hyo isolate. All animals in the study were necropsied at D61.

(33) Results and Discussion

(34) Upon necropsy, lungs were scored. Group 1, vaccinated with M. hyo antigen, only had average gross lung pathology of 5.5% (P>0.001). Group 2, vaccinated with M. hyo antigen and PCV2 antigen, had average gross lung pathology of 3.9% (P>0.001). Group 3, the challenge controls, had average gross lung pathology of 14.3% and Group 4, strict controls, had an average gross lung pathology of 0. The results are summarized below in Table 5.

(35) TABLE-US-00007 TABLE 5 Efficacy of Ingelvac MycoFLEX as a monovalent and after mixing with CircoFLEX Treatment Average Gross Lung Group Pathology (% of lung) Ingelvac MycoFLEX 5.5% (P < 0.001) MycoFLEX mixed with 3.9% (P < 0.001) CircoFLEX Challenge Controls 14.3% Strict Controls 0

(36) The results of this study show that the difference in lung pathology, between those pigs vaccinated with M. hyo antigen alone versus those pigs vaccinated with a combination of M. hyo and PCV2 antigens, was not statistically significant. Therefore, this study shows that surprisingly, PCV2 antigen does not interfere with the immunogenic effect of the M. hyo antigen component. This makes the combination vaccine comprising M. hyo antigen and PCV2 antigen efficacious for infection by M. hyo. Additionally, it shows that this novel combination of antigens can be mixed and still provide the necessary protection against these pathogens after a single dose.

Example 4

(37) This investigation was carried out to determine the efficacy of the composition, comprised of M. hyo antigen and PCV2 antigen, when challenged with PCV2.

(38) Materials and Methods

(39) The PCV2 efficacy evaluation was performed in sixty caesarian-derived, colostrum-deprived piglets. At approximately three weeks of age, piglets were vaccinated with INGELVAC MYCOFLEX, INGELVAC PRRS MLV and INGELVAC CIRCOFLEX in a single 2 ml dose. On day 31 post vaccination, vaccinate and control animals were administered a virulent PCV2 challenge virus. Twenty-two days following the administration of the challenge material, all animals were euthanized and the select tissues were removed and submitted for histology and immunohistochemistry (IHC) for PCV2. All procedures for handling and housing the piglets were observed as described in Example 1.

(40) Results and Discussion

(41) The criteria for the PCV2 efficacy evaluation were lymphoid depletion, lymphoid inflammation, and lymphoid IHC. The vaccinated group had 0% lymphoid depletion, 4.2% (1/24) lymphoid inflammation, and 8.3% (2/24) lymphoid IHC. The control group had 83.3% (20/24) lymphoid depletion, 87.5% (21/24) lymphoid inflammation, and 91.7% (22/24) lymphoid IHC. The results are summarized below in Table 6.

(42) TABLE-US-00008 TABLE 6 Summary of PCV2 Primary Challenge Results Lymphoid Lymphoid Lymphoid depletion +/total inflammation +/total IHC +/total Treatment (%) (%) (%) Vaccine 0/24 (0.0%) 1/24 (4.2%) 2/24 (8.3%)_ Controls 20/24 (83.3%) 21/24 (87.5%) 22/24 (91.7%) P-value between <0.0001 <0.0001 <0.0001 groups

(43) There were no injection site or other adverse reactions that could be attributed to the vaccine mixture.

(44) The results, together with the results of the M. hyo challenge study described in Example 1, demonstrate that the mixture of M. hyo antigen and PCV2 antigen delivered in a single 2 ml dose is efficacious against infections by M. hyo and PCV2. The ability to mix these antigens provides needed protection against the pathogens M. hyo and PCV2 as well as decreasing the number of injection sites and subsequent stress on the animal while decreasing the labor required to administer two separate vaccines without sacrificing the safety of the individual vaccines. Further this demonstrates that the vaccine combination is efficacious for infection against PCV2.

Example 5

(45) This example determined the number of mice producing detectable levels of antibodies to M. hyo or PCV2 after receiving an administration of an immunogenic composition comprising M. hyo antigen or PCV2 antigen in accordance with the present invention.

(46) Materials and Methods

(47) Antibody production was measured in mice from 5 different treatment groups, each having 20 mice therein. The first group received a dose of M. hyo antigen, the second and third groups received a dose of PCV2 antigen, and the last two groups served as a control group and received a dose of physiological saline and CARBOPOL. Each mouse in Group 1 received a 0.1 ml administration of IVP-1 (monovalent M. hyo antigen) from serial 273-011B that had a release RP of 1.44 and an RP of 1.22 at 18 months (see Example 1 above). Prior to administration, the M. hyo antigen for each dose in Group 1 was diluted 1:4. Thus, the amount of antigen administered to the mice was 40-fold less than the amount of antigen administered to pigs in Example 1. Each mouse in Group 2 received a 0.2 ml administration of PCV2 antigen serial 309-035 (release RP of 1.38) (See Example 1 above). Similar to the M. hyo antigen for Group 1, the PCV2 antigen for each dose of Group 2 was diluted 1:2 with physiological saline such that it contained one-tenth of the PCV2 antigen administered to the pigs in Example 1 above. Each mouse in Group 3 received a 0.2 ml administration of PCV2 antigen serial 309-035 (release RP of 1.38) that had been diluted 1:4 with physiological saline such that it contained one-twentieth of the PCV2 antigen administered to the pigs in Example 1 above. Groups 4 and 5 each received a 0.1 ml (Group 4) or 0.2 ml (Group 5) administration of physiological saline/CARBOPOL. After 21 days, antibody production was measured using a specific M Hyo antibody detection assay (ELISA) for Groups 1 and 4, and using a specific PCV2 antibody detection assay (ELISA) for groups 2, 3, and 5. If detectable amounts of antibodies were found using the assay, the result was termed positive. If detectable amounts of antibodies were not found using the assay, the result was termed negative.

(48) Results

(49) All mice in Group 1 were found to have detectable levels of M. hyo antibodies and all mice in Group 2 were found to have detectable levels of PCV2 antibodies 21 days after administration of the antigen-containing composition. In contrast, no detectable levels of M. hyo antibodies were found in Group 4 and no detectable levels of PCV2 antibodies were found in Group 5 21 days after administration of the physiological saline/CARBOPOL composition. Thus, one-fortieth of the antigen effective at inducing a protective immune response in pigs was able to produce detectable amounts of antibodies to M. hyo in 100% of mice receiving an administration of a composition in accordance with the present invention. This amount was defined as an RP of 1.22 for M. hyo. Moreover, one-tenth of the antigen effective at inducing a protective immune response in pigs was able to produce detectable amounts of antibodies to PCV2 in 100% of mice receiving an administration of a composition in accordance with the present invention. This amount was defined as an RP of 1.38 for PCV2.