One Dose of a Novel Vaccine Containing Two Genotypes of Porcine Circovirus (PCV2a and PCV2b) and Mycoplasma hyopneumoniae Conferred a Duration of Immunity of 23 Weeks

Abstract

Porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae (Mhyo) are important swine pathogens for which vaccination is a key control strategy. Three separate studies were performed to evaluate the duration of immunity (DOI) conferred by a novel vaccine combining PCV2a/PCV2b and Mhyo into a ready-to-use formulation. In each study, three-week-old naïve piglets were vaccinated (Day 0) and challenged 23-weeks later (Day 159) with either PCV2a, PCV2b or Mhyo. Pigs were euthanized three-to-four-weeks post-challenge. Vaccinated pigs had significantly lower PCV2 viremia from Day 168 until Day 175 (PCV2a study) or until euthanasia (PCV2b study), respectively. Fecal shedding was significantly lower for PCV2a-challenged from Day 171 until Day 178, and for PCV2b-challenged from Day 172 until euthanasia. In the PCV2a challenge study, there were no differences among vaccinates and controls in terms of percent of pigs positive for PCV2 immunohistochemistry, histiocytic replacement, or lymphoid depletion. However, significant differences for immunohistochemistry and histiocytic replacement, not lymphoid depletion, were observed among vaccinates and controls following PCV2b challenge. Vaccination supposed a significant reduction in the mean percentage of Mhyo-like lesions in the lung. Percentages of lung tissues positive for Mhyo via immunohistochemistry were 49.3% and 67.1% for vaccinated and control groups, respectively. One dose of the novel PCV2a/PCV2b/Mhyo vaccine conferred robust protection against challenge 23-weeks later for all three fractions.

Design of a New Vaccine Prototype against Porcine Circovirus Type 2 (PCV2), M. hyopneumoniae and M. hyorhinis Based on Multiple Antigens Microencapsulation with Sulfated Chitosan

“…Other studies [52][53][54][55][56], describe multivalent vaccines containing antigens against M. hyopneumoniae and PCV2. In addition, other authors described the possible use of multivalent vaccine antigens PCV2 and M. hyopneumoniae [57][58][59], while other researchers propose further combinations with additional antigens that come from a microorganism that causes disease in pigs, including M. hyorhinis antigen [10].…”

A bivalent porcine circovirus type 2 (PCV2), PCV2a-PCV2b, vaccine offers biologically superior protection compared to monovalent PCV2 vaccines

“…The RT-qPCR was conducted in a thermocycler (Bio-Rad CFX 96). The sequences of primers and probe were as described [ 30 ]. The number of DNA copies obtained are expressed as number of copies per 5 μL.…”

Efficacy Studies against PCV-2 of a New Trivalent Vaccine including PCV-2a and PCV-2b Genotypes and Mycoplasma hyopneumoniae When Administered at 3 Weeks of Age

“…DNA from pre-clinical serum and faecal samples were extracted and qPCR-analysed with a non-commercial in-house qPCR as indicated in Mancera-Gracia et al [6]. No threshold was applied; therefore, all detected values were reported as positive.…”

“…As other ssDNA, PCV-2 has a high mutation rate, being around 10 3 -10 4 substitutions/site/year [6]. Additionally, PCV-2 can also evolve by means of recombination [7][8][9].…”

“…Additionally, PCV-2 can also evolve by means of recombination [7][8][9]. These two factors result in genetic changes and a wide diversity within PCV-2 [6,10]. In fact, nowadays, nine genotypes of PCV-2 are recognised (a-i) based on ORF2 gene sequencing [8,11], three of them (a, b and d) being the most frequently associated with clinical PCV2-SD [12].…”