the following examples set forth preferred materials and procedures in accordance with the present invention . although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention , the preferred methods , devices , and materials are now described . 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 . initial sf + cell cultures from liquid nitrogen storage were grown in excell 420 media ( jrh biosciences , inc ., lenexa , kans .) in suspension in sterile spinner flasks with constant agitation . the cultures were grown in 100 ml to 250 ml spinner flasks with 25 to 150 ml of excell 420 serum - free media . when the cells had multiplied to a cell density of 1 . 0 - 8 . 0 × 10 6 cells / ml , they were split to new vessels with a planting density of 0 . 5 - 1 . 5 × 10 6 cells / ml . subsequent expansion cultures were grown in spinner flasks up to 36 liters in size or in stainless steel bioreactors of up to 300 liters for a period of 2 - 7 days at 25 - 29 ° c . after seeding , the flasks were incubated at 27 ° c . for four hours . subsequently , each flask was seeded with a recombinant baculovirus containing the pcv2 orf - 2 gene ( seq id no : 4 ). the recombinant baculovirus containing the pcv2 orf - 2 gene was generated as described in wo06 / 072065 . after being seeded with the baculovirus , the flasks were then incubated at 27 ± 2 ° c . for 7 days and were also agitated at 100 rpm during that time . the flasks used ventilated caps to allow for air flow . after incubation , the resulting supernatant were harvested , filtered in order to remove cell debris , and inactivated . the supernatant was inactivated by bringing its temperature to 37 ± 2 ° c . and binary ethlylenimine ( bei ) was added to the supernatant to a final concentration of 5 mm . the samples were then stirred continuously for 72 to 96 hrs . a 1 . 0 m sodium thiosulfate solution to give a final minimum concentration of 5 mm was added to neutralize any residual bei . after inactivation , pcv2 orf - 2 buffered with phosphate buffer and carbopol was added to about 0 . 5 to 2 . 5 mg / dose . the final dose comprises about 16 μg pcv2 orf - 2 antigen . pk15 ( e . g . atcc ccl - 33 ) or vido r1 cells described in wo 02 / 07721 , are seeded onto a 96 well plate ( about 20 . 000 to 60 . 000 cells per wells ). cells are infected with a pcv2 isolate , when monolayers are approximately 65 to 85 % confluent . infected cells are incubated for 48 hours . medium is removed and wells are washed 2 times with pbs . the wash buffer is discarded and cells are treated with cold 50 / 50 methanol / acetone fixative (˜ 100 μl / well ) for about 15 min at about − 20 ° c . the fixative is discarded and the plates are air dried . serial dilutions of porcine serum samples are prepared in pbs , added to the plates and incubated to allow antibodies to bind if present in the serum samples for about 1 hr at 36 . 5 ± 1 ° c . in addition , serial dilutions of an anti - pcv2 positive and negative control sample ( positive control and negative control samples ) are run in parallel . the plates are then washed three times with pbs . the pbs is discarded . plates are then stained with a commercial goat anti - swine fitc conjugate diluted 1 : 100 in pbs and incubated for about 1 hr at 36 . 5 ± 1 ° c ., which allows detection of antibodies bound to infected cells . after incubation is complete , the microplates are removed from incubator , the conjugate is discarded and the plates are washed 2 times with pbs . the plates are read using uv microscopy and individual wells reported as positive or negative . the positive control and negative control samples are used to monitor the test system . if the controls are within expected ranges the test results are acceptable in regard to test method parameters . the serum antibody titers are calculated using the highest dilution showing specific ifa reactivity and the number of wells positive per dilution , or a 50 % endpoint is calculated using the appropriate reed - muench formula . the purpose of this study was the demonstration of the efficacy of ingelvac ® circoflex in the control of pcv2 - associated prdc . 1542 conventional pigs belonging to three consecutive week groups , each comprising approximately 500 animals , were included into the study . the study animals were blocked by weight and litter assignment and randomly assigned to one group of vaccinates ( n = 769 ) and one control group ( n = 773 ). group 1 : at study day 0 the pigs were vaccinated intramusculary at the age of approximately 20 days by a single dose of ingelvac ® circoflex containing pcv2 orf - 2 protein as the active substance with an rp of 1 ( per dose of 1 ml ) and carbopol ® as adjuvant . group 2 : the control group received 1 ml of control article which contained pcv2 orf - 2 protein free cell culture supernatant and carbopol ® as adjuvant . group 3 : untreated pigs . the study was terminated at the end of fattening ( study week 22 ). individual body weight ( all animals ) frequency of ‘ runts ’ ( all animals ) clinical signs ( all animals ) mortality ( all animals ) pcv2 viremia in serum : onset , end , duration of viremia , virus load according to the disease history of the rearing and fattening farm , animals experienced respiratory symptoms related to the porcine respiratory disease complex ( prdc ) from the middle of fattening onwards . these symptoms were accompanied by a reduced weight gain ( adwg 750 - 780 g ) and an increased mortality rate ( 5 . 5 - 6 . 6 %) during the fattening period . pathogens that were considered to be involved in prdc at that time were pcv2 , prrsv , pasteurella multocida , bordetella bronchiseptica and occasionally siv . for the course of this study mycoplasma hyopneumoniae and mycoplasma hyorhinis were additionally found to be involved in this disease complex . interestingly , results from this study give evidence for the fact that both the prrsv and the mycoplasma hyopneumoniae infection occurred approximately 4 - 6 weeks before onset of pcv2 viremia . however , as the number of dead animals over the course of the study and the frequency of respiratory symptoms before and after the onset of pcv2 viremia reveal , animals remained rather unaffected from these two infectious pathogens . body weight of the two treatment groups was comparable at the time of study initiation . at study weeks 17 and 22 , the body weight of the vaccinated group was significantly higher than the body weight of the placebo - treated group ( p = 0 . 0007 and p & lt ; 0 . 0001 , respectively ). from study initiation until study week 22 , vaccinated animals had gained 2 . 8 kg more weight than placebo - treated animals . this corresponds to a 13 g / d higher adwg in vaccinated animals from study initiation until study week 17 and an 18 g / d higher adwg in vaccinated animals until study week 22 . for the entire fattening period ( study week 7 - 22 ), the adwg could thus be increased from 777 g / d in placebo - treated animals ( comparable to historical 750 - 780 g / d adwg ) to 803 g / d in vaccinated animals ( table 1 and fig1 ). vaccinated animals showed a slightly later onset of viremia ( 1 . 5 days later ), a significantly earlier end of viremia ( p & lt ; 0 . 0001 ), a significantly shorter duration of viremia ( p & lt ; 0 . 0001 ), a significantly lower number of positive sampling days per animal ( p & lt ; 0 . 0001 ) and a significant general reduction in the virus load ( p & lt ; 0 . 0001 ). the highest proportion of viremic animals was observed at study week 17 with 75 % viremic animals in the placebo group and 28 % viremic animals in the vaccinated group . fig2 illustrates the virus load in sample animals of both treatment groups over the course of the study compared to the difference in live body weight ( cp - ivp ) of all animals from both treatment groups on the respective weighing time points . when comparing the curves for body weight difference with the bars representing the virus load , it becomes obvious that the observed differences in body weight between both treatment groups ( study weeks 17 and 22 ) occur after the onset of viremia ( study week 14 - 16 ). while the virus load is decreasing after a peak at study week 17 , the difference in body weight between groups is further increasing until the end of fattening . together these data give evidence for a correlation between the observed higher body weight gain development at study weeks 17 and 22 in the vaccinated group and the onset , duration and level of viremia . calculation of the spearman rank coefficient confirmed the existence of a statistical significant correlation between viremia and the difference in weight gain development in placebo - treated animals at study weeks 17 and 22 . a low body weight in placebo - treated animals was correlated with an early onset , a long duration of viremia and a high virus load . for vaccinated animals no such correlation could be found indicating that the higher body weight in the vaccinated animals was the result of a delayed onset and shorter duration of viremia as well as of a lower virus load in blood . no significant differences in the frequency of ‘ runts ’ could be observed between the vaccinated and the placebo - treated group on any of the respective weighing time points . after the onset of pcv2 viremia ( study week 14 - 16 ), the frequency of ‘ runts ’ was generally low in both treatment groups ( 2 . 2 - 3 . 9 %). before onset of viremia predominant clinical signs were lamenesses , cough and diarrhea ( in 8 - 12 % of animals ). they occurred with equal frequency in both treatment groups . upon necropsy of dead animals and subsequent microbiological examination streptococcus suis was identified as a possible infectious pathogen for lamenesses , haemophilus parasuis and bordetella bronchiseptica were identified as possible infectious pathogens for cough , and haemolytic e . coli was identified as a possible reason for diarrhea . after the onset of viremia , the predominant clinical symptoms observed in animals of both treatment groups were cough and lamenesses . serological periodic analyses for other infectious pathogens and microbiological findings upon necropsy revealed that pcv2 viremia was accompanied by a ( preceding ) prrsv and mycoplasma hyopneumoniae infection . together with pcv2 , these infectious pathogens form part of prdc which is considered to be the cause for the increased frequency of coughing animals after the onset of viremia . compared to the placebo - treated animals , the frequency of cough and dyspnea in vaccinated animals was reduced by 12 . 2 % and 17 . 5 %, respectively . these findings are however without any statistical significance . the increased frequency of lamenesses after the onset of viremia compared to the time before onset of viremia is most likely caused by chronic forms of streptococcus suis , arthritis , or by weaknesses of the joint apparatus and these affected both treatment groups in the same way ( p = 0 . 8321 ). similarly , the frequency of other clinical findings ( diarrhea , skin abnormalities , behaviour ) after the onset of viremia was almost equal between the two treatment groups . before onset of viremia the mortality rate was comparable in both treatment groups ( vaccinated animals : 5 . 20 %, placebo - treated animals : 5 . 17 %). after the onset of viremia placebo - treated animals had a significant higher mortality rate than vaccinated animals ( vaccinated animals : 1 . 51 %, placebo - treated animals : 3 . 68 %, p = 0 . 0127 ). compared to placebo - treated animals , the mortality rate in vaccinated animals was reduced by 59 %. the study has been conducted on a farm that showed typical symptoms of prdc at the late phase of fattening . at the age of 17 to 19 weeks , pigs developed respiratory symptoms , an increased mortality rate , and a loss of weight gain . upon serological and microbiological screening pcv2 , prrsv , mycoplasma hyopneumoniae , mycoplasma hyorhinis and pasteurella multocida were identified as possible pathogens being involved in this disease complex . compared to the placebo - treated control group the following statistically significant findings were noted for the vaccinated group : reduction of loss of weight gain reduction of mortality reduction of the duration of viremia and earlier end of viremia reduction of the virus load reduction of cough and dyspnea as expected , no statistically significant differences could be observed with regard to the frequency of ‘ runts ’ since the occurrence of ‘ runts ’ is not a typical finding for prdc . 1 . the study has been conducted in a herd that got affected with prdc at the middle to late phase of fattening . pcv2 was clearly involved in this disease complex since respiratory symptoms , loss of weight gain and an increase in mortality was only observed after the onset of viremia . 2 . vaccination of animals with ingelvac ® circoflex ™ could reduce or even prevent clinically relevant parameters that are related to pcv2 associated prdc
the present invention relates to the use of an immunogenic composition comprising a porcine circovirus type 2 antigen for the prevention and treatment , including a reduction in the severity of , duration of , and manifestations of , porcine respiratory disease complex in animals , preferably in pigs .