Su-Jin Park

Induction of neutralizing antibody in mice by immunization with recombinant 56 kDa protein of Orientia tsutsugamushi

Anti-oriential antibody inhibits Orientia tsutsugamushi attachment to, and penetration of, host cells. However, O. tsutsugamushi antigens that induce the production of a neutralizing antibody have not been identified. The authors immunized mice and rabbits with the recombinant 56 kDa protein of O. tsutsugamushi fused to the maltose binding protein of Escherichia coli (MBP-Bor56) and analysed their effect on O. tsutsugamushi attachment to or penetration of L929 cells. O. tsutsugamushi attachment and penetration were measured by using an indirect immunofluorescent antibody assay (IFA). O. tsutsugamushi growth in L929 cells was determined by [3H]thymidine uptake assay. By IFA, we observed a 96% reduction of attachment or penetration of O. tsutsugamushi treated with rabbit anti-MBP-Bor56 sera. [3H]thymidine uptake showed that mouse anti-MBP-Bor56 sera caused a 91% reduction in O. tsutsugamushi growth, when compared to mouse anti-MBP sera. These results suggest that the 56 kDa protein of O. tsutsugamushi plays an important role in O. tsutsugamushi attachment to or penetration of cells.

Genetic and antigenic characterization of a newly emerging porcine circovirus type 2b mutant first isolated in cases of vaccine failure in Korea

This study describes the genetic and antigenic characterization of a newly emerging porcine circovirus type 2b (PCV2b) mutant first isolated in cases of vaccine failure in Korea. The full genome of the PCV2b isolates (SNUVR130689 and SNUVR140004) is 1,767 base pairs (bp) in length. The size of ORF1 is 945xa0bp, encoding a protein of 314 amino acids (aa), and the size of ORF2 is 705xa0bp, encoding a protein of 234xa0aa, which is 1xa0aa longer than that of the common PCV2 (233xa0aa). Korean PCV2b mutant strains had higher levels of nucleotide sequence identity to other PCV2b mutant strains (99.7–99.8xa0%) than to reference PCV2a (94.5–95.0xa0%) and PCV2b (95.5–96.1xa0%) strains. There was no difference in antigenic reactivity among PCV2a, PCV2b and PCV2b mutant strains to the polyclonal and monoclonal PCV2a antibodies. PCV2b mutant strains have distinct genetic characteristics but similar antigenic reactivity when compared to common PCV2a and 2b strains.

Comparison of Two Commercial Type 1 Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) Modified Live Vaccines against Heterologous Type 1 and Type 2 PRRSV Challenge in Growing Pigs

ABSTRACT The objective of the present study was to compare the efficacy of two commercial type 1 porcine reproductive and respiratory syndrome virus (PRRSV) modified live vaccines against heterologous type 1 and type 2 PRRSV challenge in growing pigs. Vaccination with a type 1 PRRSV vaccine reduced the level of viremia after type 1 PRRSV challenge but did not reduce the level of viremia after the type 2 PRRSV challenge in pigs. Increased levels of interleukin-10 (IL-10) stimulated by type 2 PRRSV coincided with the low numbers of type 2 PRRSV-specific interferon gamma-secreting cells (IFN-γ-SC) in vaccinated pigs after type 2 PRRSV challenge, whereas low levels of IL-10 stimulated by type 1 PRRSV coincided with high numbers of type 1 PRRSV-specific IFN-γ-SC in vaccinated pigs after type 1 PRRSV challenge. Additionally, vaccination with the type 1 PRRSV vaccine effectively reduced the lung lesions and type 1 PRRSV nucleic acids in type 1 PRRSV-challenged pigs but did not reduce lung lesions and type 2 PRRSV nucleic acids in type 2 PRRSV-challenged pigs. There were no significant differences between two commercial type 1 PRRSV vaccines against type 1 and type 2 PRRSV challenge based on virological results, immunological responses, and pathological outcomes. This study demonstrates that vaccinating pigs with the type 1 PRRSV vaccine provides partial protection against respiratory disease with heterologous type 1 PRRSV challenge but no protection with heterologous type 2 PRRSV challenge.

Interaction of porcine circovirus type 2 and Mycoplasma hyopneumoniae vaccines on dually infected pigs

The objective of this study was to determine the effects of porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae vaccinations on disease severity in an experimental PCV2-M. hyopneumoniae dual challenge model. Vaccine effectiveness was evaluated using microbiological (PCV2 viremia and M. hyopneumoniae nasal shedding), immunological (neutralizing antibodies and interferon-γ-secreting cells), and pathological (gross lung lesions, histopathologic pulmonary and lymphoid lesions, and the presence of PCV2 antigen and M. hyopneumoniae DNA within the lesions) evaluations. Although M. hyopneumoniae potentiates the severity of PCV2-associated lesions and lesion-associated PCV2 antigen in dually challenged pigs, vaccination against M. hyopneumoniae alone did not reduce PCV2 viremia, PCV2-induced lesions, or PCV2 antigen in dually challenged pigs. In addition, vaccination against PCV2 did not reduce the nasal shedding of M. hyopneumoniae, the M. hyopneumoniae-induced pulmonary lesions or the lesion-associated M. hyopneumoniae DNA in dually challenged pigs. Dual challenge with PCV2 and M. hyopneumoniae did not interfere with the induction of active immunity induced by a previous single vaccination for either PCV2 or M. hyopneumoniae. The results of this study demonstrated that (i) vaccination against M. hyopneumoniae alone did not decrease the potentiation of PCV2-induced lesions by M. hyopneumoniae and (ii) vaccination against PCV2 alone decreased the potentiation of PCV2-induced lesions by M. hyopneumoniae in dually challenged pigs.

Interaction between single-dose Mycoplasma hyopneumoniae and porcine reproductive and respiratory syndrome virus vaccines on dually infected pigs.

The objective of this study was to determine the effects of Mycoplasma hyopneumoniae and/or porcine reproductive and respiratory syndrome virus (PRRSV) vaccination on dually infected pigs. In total, 72 pigs were randomly divided into nine groups (eight pigs per group), as follows: five vaccinated and challenged groups, three non-vaccinated and challenged groups, and a negative control group. Single-dose vaccination against M. hyopneumoniae alone decreased the levels of PRRSV viremia and PRRSV-induced pulmonary lesions, whereas single-dose vaccination against PRRSV alone did not decrease nasal shedding of M. hyopneumoniae and mycoplasma-induced pulmonary lesions in the dually infected pigs. The M. hyopneumoniae challenge impaired the protective cell-mediated immunity induced by the PRRSV vaccine, whereas the PRRSV challenge did not impair the protective cell-mediated immunity induced by the M. hyopneumoniae vaccine. The present study provides swine practitioners and producers with efficient vaccination regimes; vaccination against M. hyopneumoniae is the first step in protecting pigs against co-infection with M. hyopneumoniae and PRRSV.

Comparison of porcine circovirus type 2 (PCV2)-associated lesions produced by co-infection between two genotypes of PCV2 and two genotypes of porcine reproductive and respiratory syndrome virus.

The objective of this study was to compare the virulence and pathogenicity of a combination of concurrent infections of two genotypes of porcine circovirus type 2 (PCV2) and two genotypes of porcine reproductive and respiratory syndrome virus (PRRSV) in terms of PCV2 viraemia, and PCV2-associated lesions and antigens in co-infected pigs. Pigs with PCV2a (or 2b)/type 1 (or type 2) PRRSV had significantly (P<0.05) higher mean clinical respiratory scores and lower average daily weight gain compared with pigs with PCV2a (or 2b). Co-infection induced significantly lower levels of anti-PCV2 and anti-PRRSV IgG antibodies than infection with one genotype alone, regardless of the genotype of the two viruses. Pigs with PCV2a (or 2b)/type 2 PRRSV had significantly (P<0.05) higher levels of PCV2 viraemia, more severe PCV2-associated lesions, and more PCV2 DNA within the lesions compared with pigs with PCV2a (or 2b)/type 1 PRRSV. However, there was no significant difference in these parameters in pigs with PCV2a/type 2 PRRSV or PCV2b/type 2 PRRSV. The results of this study demonstrate significant differences in the virulence and pathogenicity of type 1 and type 2 PRRSV but no significant differences in the virulence and pathogenicity of PCV2a and PCV2b with respect to the production of PCV2-associated lesions.

Concurrent vaccination of pigs with type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) protects against type 1 PRRSV but not against type 2 PRRSV on dually challenged pigs.

The objective of the present study was to evaluate the effect of concurrent vaccination of pigs with both type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) vaccine against heterologous dual challenge of both genotypes and compare with single vaccination of pigs against heterologous single challenge of both genotypes. Pigs were administered both type 1 and type 2 PRRSV vaccine concurrently into separate anatomical sites at 28 days of age and inoculated intranasally with both genotypes at 63 days of age. Neutralizing antibodies (NA) were not detected in any pigs in any group (NA titer <2 log2) throughout the experiment. In addition, concurrent vaccination of pigs with two PRRSV genotypes had significantly lower numbers of type 1 and type 2 PRRSV-specific interferon-γ secreting cells (IFN-γ-SC) compared to vaccination of pigs with type 1 or type 2 PRRSV only. Despite the decreased induction of type 1 PRRSV-specific IFN-γ-SC, concurrent vaccination is still able to reduce type 1 PRRSV viremia whereas the decreased induction of type 2 PRRSV-specific IFN-γ-SC by concurrent vaccination correlates with lack of reduction of type 2 PRRSV viremia after dual challenge. The results of this study demonstrated that concurrent vaccination of pigs with two PRRSV genotypes is able to reduce the levels of type 1 PRRSV viremia and lung lesions but not able to reduce the levels of type 2 PRRSV viremia and lung lesions.

Vaccination with a porcine reproductive and respiratory syndrome virus vaccine at 1-day-old improved growth performance of piglets under field conditions

A porcine reproductive and respiratory syndrome virus (PRRSV) modified live-virus (MLV) vaccine was evaluated under field conditions for registration as recommended by the Republic of Koreas Animal, Plant & Fisheries Quarantine & Inspection Agency. A single dose of the vaccine was administered to 1-day-old piglets and their growth performance was monitored under field conditions. Three separate farms were selected based on their history of PRRSV-associated respiratory diseases. On each farm, 40 pigs were randomly allocated to one of two treatment groups: (i) vaccinated (nu202f=u202f20) and (ii) unvaccinated (nu202f=u202f20) pigs at 1u202fday of age. Vaccinated pigs showed an increase of their market weight of 6.23u202fkg/pig compared to the unvaccinated pigs (98.01u202fkg in vaccinated group vs. 91.78u202fkg in unvaccinated group; Pu202f<u202f0.05) and exhibited a decrease in mortality rate by 6.7% (3.3% in vaccinated group vs. 10% in unvaccinated group; Pu202f<u202f0.05). The pigs had a sufficiently mature immune system for the vaccine to elicit humoral and cell-mediated immunity (as measured by anti-PRRSV antibodies and PRRSV-specific interferon-γ secreting cells, respectively) at 1u202fday of age even in the presence of maternally derived antibodies. The results presented in this study demonstrate that the PRRSV MLV vaccine is effective in improving growth performance from day 1 all the way to day 182 in endemic farms suffering with PRRSV-2 infection or both PRRSV-1 and PRRSV-2 infection.

A comparison of the severity of reproductive failure between single and dual infection with porcine reproductive and respiratory syndrome virus (PRRSV)-1 and PRRSV-2 in late-term pregnancy gilts

The objective of this study was to compare the severity of reproductive failure caused by either a single or a dual infection with porcine reproductive and respiratory syndrome virus (PRRSV)-1 and PRRSV-2 in late-term pregnancy gilts. Pregnant gilts were intranasally administered PRRSV-1, PRRSV-2 or both at 3xa0weeks before the expected farrowing date (93xa0days of gestation). Regardless of single and dual infection, PRRSV-infected pregnant gilts experienced premature farrowing (103-109xa0days of gestation) compared with negative control gilts which carried their pregnancy to full term (114-115xa0days of gestation). Pregnant gilts infected with only PRRSV-1 had a significantly (pxa0<xa00.05) higher number of genomic copies of PRRSV-1 in their blood compared with dually infected gilts. Additionally, stillborn foetuses and live-born piglets from pregnant gilts infected with only PRRSV-1 had a significantly (pxa0<xa00.05) higher number of PRRSV-1-positive cells per unit area of tissue sections examined, compared to pregnant gilts dually infected with PRRSV-1 and PRRSV-2. In contrast, pregnant gilts infected with only PRRSV-2 showed no difference in the number of genomic copies of PRRSV-2 compared with dually infected pregnant gilts and there were no significant differences in PRRSV-2-positive cells per unit area in tissues of stillborn foetuses and live-born piglets from pregnant gilts infected with PRRSV-2 only compared with dually infected gilts. Interestingly, even though PRRSV-2 was shown to replicate more efficiently compared with PRRSV-1 in dually infected pregnant gilts, neither PRRSV type was able to exacerbate reproductive failure in pregnant gilts already dually infected with PRRSV-1 and PRRSV-2. Our results suggest that the severity of reproductive failure is similar between dual (PRRSV-1 and PRRSV-2) and single infection (PRRSV-1 or PRRSV-2).

Evaluation of the effect of a porcine reproductive and respiratory syndrome (PRRS) modified-live virus vaccine on sow reproductive performance in endemic PRRS farms

The efficacy of a porcine reproductive and respiratory syndrome (PRRS) modified-live virus vaccine in reproductive performance was evaluated under field conditions. Three PRRS endemic farms were selected based on their history of PRRS-associated reproductive failures. On each farm, a total of 40 sows were randomly allocated to either vaccinated (n=20) or unvaccinated (n=20) groups. Sows were vaccinated six weeks prior to breeding. Clinical data showed a significant improvement in reproductive performance in vaccinated sows. Sows in the vaccinated groups had a significantly (P<0.05) reduced number of stillborn piglets in all 3 farms. Sows in the vaccinated groups also had a significantly (P<0.05) higher number of live-born piglets in one of the farms. Sows in the vaccinated groups had a significantly (P<0.05) higher number of weaned piglets in two of the farms. Premature farrowing, one of the late gestation symptoms of PRRS, was also reduced due to vaccination as suggested by the increase in gestation length and the reduction in the number of stillborn piglets. No adverse systemic or local side effects relative to vaccination were observed during the entire gestation. No vaccine strain was detected in the vaccinated sows from all three farms at 70 and 114days post vaccination and in live-born piglets at the time of farrowing. Vaccination of sows with this PRRS vaccine was effective in improving reproductive performance in endemic PRRS farms.