Effects of an Inactivated Porcine Circovirus Type 2 (PCV2) Vaccine on PCV2 Virus Shedding in Semen from Experimentally Infected Boars

Abstract

The objective of the present study was to determine the effect of an inactivated porcine circovirus type 2 (PCV2) vaccine on PCV2b virus shedding in the semen of experimentally infected boars by measuring the immunological response and the PCV2b DNA load in blood and semen. Twelve boars were randomly divided into three groups. The boars in group 1 (n ‫؍‬ 4) were immunized with an inactivated PCV2 vaccine and were challenged with PCV2b. The boars in group 2 (n ‫؍‬ 4) were only challenged with PCV2b. The boars in group 3 (n ‫؍‬ 4) served as negative controls. The number of PCV2 genome copies of PCV2 in the serum and semen were significantly lower in vaccinated challenged boars than in nonvaccinated challenged boars at 7, 10, 14, 21, 32, 35, 42, 49, and 60 days postinoculation. The number of PCV2b genomes in the semen correlated with the number of PCV2b genomes in the blood in both vaccinated challenged (R ‫؍‬ 0.714) and nonvaccinated challenged (R ‫؍‬ 0.861) boars. The results of the present study demonstrate that the inactivated PCV2 vaccine significantly decreases the amount of PCV2b DNA shedding in semen from vaccinated boars after experimental infection with PCV2b.Porcine circovirus type 2 (PCV2) is associated with a number of diseases and syndromes collectively referred to as porcine circovirus-associated disease (PCVAD), which includes postweaning multisystemic wasting disease (PMWS), porcine dermatitis and nephropathy syndrome (PDNS), reproductive failure, porcine respiratory disease complex (PRDC), and exudative epidermitis (3).Several commercial PCV2 vaccines are currently available in the global market. All PCV2 vaccines have been administered to either sows or piglets (2,5,16,18). Commercial PCV2 vaccines are able to reduce the PCV2 load in the serum and reduce PCV2 shedding in nasal and fecal samples in conventional pigs (5,15,16,18). Recently, it has also been reported that vaccination against PCV2 in naturally infected boars can decrease the duration of viral shedding in semen (1). These data strongly imply that vaccination against PCV2 may reduce the subsequent shedding of PCV2 in the semen of boars. Therefore, the objective of the present study was to determine the effect of PCV2 vaccination on the shedding of the PCV2 virus in the semen of experimentally infected boars. MATERIALS AND METHODSCommercial vaccine and PCV2 inoculum. The commercial inactivated tissue homogenate PCV2 vaccine based on PCV2 genotype 2b, CircoPrime (Komipharm International Company Ltd., Shiheung-shi, Kyongki-do, Republic of Korea), was used in this study. It was administered intramuscularly in two 2.0-ml doses separated by 3 weeks.The PCV2 strain (PCV2 genotype b) isolated from the superficial inguinal lymph node of a field case of PMWS was used as the inoculum. The virus was propagated in PCV-free PK15 cells to a titer of 10 5 50% tissue culture infective doses (TCID 50 s)/ml.Experimental design. At 8 months of age, 12 purebred, male, Landrace pigs were purchased from a commercial farm. All boars were negative for PCV2 and...

Evaluation of a Virus-like Nanoparticle Porcine Circovirus Type-2 (PCV2) Capsid Protein Fused with the Pig Immunoglobulin Fc Fragment as a Novel Vaccine Candidate against PCV2 in Mice

“…A variety of PCV2 vaccines have been developed, such as inactivated vaccines, subunit vaccines and nucleic acid vaccines, etc. [30][31][32][33]. Currently, commercial PCV2 subunit vaccines have been developed on the basis of the PCV2a strain.…”

The effect of porcine circovirus type 2 (PCV2) vaccination of male piglets on sperm quality at the age of puberty

“…The IgG level rose in the vaccinated group indicating that the increase was due to the vaccine and not due to the infection with the PCV2 field virus. Vaccinated piglets are protected against the clinical manifestation of the SD-PCV2 and the load of PCV2 -DNA in organs and tissues including the testes, epididymis and semen is lower than in the unvaccinated groups (Seo et al 2011).…”

“…Several commercial PCV2 vaccines are currently available for use in piglets or adult animals, considered to be able to reduce the clinical signs of a PCV2 infection at a farm level. It has also been reported that vaccination against PCV2 in experimentally (Seo et al 2011) or naturally (Alberti et al 2011) infected mature boars can decrease the duration of viral shedding in semen. Since a very high percentage of boars become naturally infected by PCV2 later in life, it is of importance to assess whether the vaccination early in the boar's life with a commercial PCV2 vaccine still has a beneficial effect.…”

Comparative Efficacy of Chimeric Porcine Circovirus (PCV) Vaccines against Experimental Heterologous PCV2d Challenges

“…Application of the PCV2 vaccine is a key strategy in the prevention and control of PCV2 infection, as it has been determined that clinical signs of PCVAD were reduced under both experimental and field conditions [ 8 , 9 , 10 , 11 , 12 ]. Moreover, finishing pigs vaccinated with PCV2 vaccines experienced a significant increase in average daily gain (ADG) of 41.5 g/day and a significant decrease in mortality rate of 4.4% when compared with pigs of the unvaccinated herds [ 13 ].…”