Field experience with two different vaccination strategies aiming to control infections with Actinobacillus pleuropneumoniae in a fattening pig herd

Abstract

BackgroundThe prevalence of pleurisies recorded at slaughter is increasing in Sweden, and acute outbreaks of actinobacillosis that require antimicrobial treatments have become more frequent. As an increased use of antimicrobials may result in the development of antimicrobial resistance it is essential to develop alternative measures to control the disease. Vaccinations present an appealing alternative to antimicrobial treatments. The aim of this work was to evaluate the potential of two different vaccination strategies in a specialized fattening herd affected by actinobacillosis.MethodsThe study was conducted in a specialized fattening herd employing age segregated rearing in eight units. The herd suffered from infections caused by Actinobacillus pleuropneumoniae serotype 2, confirmed by necropsy and serology. The study included 54 batches of pigs grouped into five periods. Batches of pigs of the second period were vaccinated against actinobacillosis twice, and pigs in the fourth period were vaccinated three times. Batches of pigs of the first, third and fifth period were not vaccinated. Concentrations of serum antibodies to A. pleuropneumoniae and serum amyloid A (SAA) were analysed and production data were recorded.ResultsDespite vaccinating, medical treatments were required to reduce the impact of the disease. The mean incidence of individual treatments for respiratory diseases during the rearing period ranged from 0 to 4.7 ± 1.8%, and was greatest during the triple vaccination period (period IV; p < 0.05 when compared to other groups). A large proportion of the vaccinated pigs seroconverted to A. pleuropneumoniae serotype 2 in the absence of a SAA-response. The prevalence of pleuritis decreased from 25.4 ± 6.5% in the first period to 5.0 ± 3.7% in the fifth period (p < 0.001).ConclusionsThe vaccine did not effectively prevent clinical expression of A. pleuropneumoniae infections, but seroconversion to A. pleuropneumoniae in the absence of a SAA-response in a large number pigs indicated that the vaccine had activated the immune system. Further, the prevalence of pleuritis decreased with time. This indicates that vaccinations together with intensified medical treatments of affected pigs could be useful in reducing the impact of A. pleuropneumoniae serotype 2 infections.

No Clear Effect of Initiating Vaccination against Common Endemic Infections on the Amounts of Prescribed Antimicrobials for Danish Weaner and Finishing Pigs during 2007–2013

“…However, serotype 6 is present in 26% of SPF herds, serotype 2 in 17%, serotype 7 in 0.4%, and serotype 5 in 0.1% (5). Studies have shown that vaccines against APP can reduce the prevalence of pleuritis (16, 17). Vaccines against APP are the third most frequently used type of vaccines in Danish pig production, representing 8% of the vaccine dosages prescribed in 2013 (10).…”

Immunoprotective Efficacy of Six In vivo-Induced Antigens against Actinobacillus pleuropneumoniae as Potential Vaccine Candidates in Murine Model

“…However, attenuated mutant vaccine candidates have been shown to provide a partial cross-protection and reduced morbidity ( Tonpitak et al, 2002 ; Maas et al, 2006 ). So far, DNA vaccines ( Chiang et al, 2009 ; Lu et al, 2011 ), subunit vaccines ( Sjolund and Wallgren, 2010 ; Lopez-Bermudez et al, 2014 ), recombinant subunit vaccines ( Jirawattanapong et al, 2008 ; Oldfield et al, 2008 , 2009 ; Shao et al, 2010 ; Sadilkova et al, 2012 ; Seo et al, 2013 ; Park et al, 2015 ; Li et al, 2016 ), ghost vaccine ( Katinger et al, 1999 ; Hensel et al, 2000 ), and live vector vaccine ( Shin et al, 2013 ; Hur and Lee, 2014 ) for APP had been studied.…”

Candidate genes and gene markers for the resistance to porcine pleuropneumonia

“…The main problem with a vaccination strategy appears to be a low cross-immunity between serotypes (Higgins et al 1985;Fenwick and Henry 1994). In addition, modern subunit or toxoid vaccines do not provide full protection against the clinical outbreak of the disease (e.g., reduction in mortality, increase in daily weight gain, amounts of condemnations for pneumonia) (Chiers et al 1998;Sjölund and Wallgren 2010;Jirawattanapong et al 2010;Del Pozo Sacristan et al 2014). Thus, antibiotics still prevail as the treatment of choice.…”