Monitoring of porcine circovirus type 2 infection through air and surface samples in vaccinated and unvaccinated fattening farms

Abstract

Air and surfaces of swine farms are the two alternative samples to obtain information about the health status of the herd. The aim of this study was to assess air and surface sampling for the detection of porcine circovirus type 2 (PCV2) in vaccinated and unvaccinated fattening farms, studying the relationship between the viral load in these samples with the viremia at herd level. Three swine fattening batches (one unvaccinated; two vaccinated) were monitored at 10, 12, 14, 16 and 18 weeks old; at each stage, blood, air and different surfaces were sampled and analysed by qPCR. In all herds, PCV2 was detected in all types of samples. Whenever viremia was detected, PCV2 was also detected in air and surface samples, even in those cases with a low estimated prevalence (1.6%); moreover, in two out of the three herds, PCV2 was detected in air and surface samples earlier than in the blood of the sampled population. In addition, a good correlation between the viremia of pig population and the PCV2 load in air and surface samples was found in both cases (τ = 0.672 and 0.746, respectively; p <0.05). These results show that air and surface samples could be useful tools to monitor PCV2 infection, being suitable for detecting the virus in cases of low prevalence and even before pigs develop viremia; therefore, these sampling techniques would speed up the implementation of the required measures to prevent productive and economic losses due to PCV2 infection.

Pathogenic Ecological Characteristics of PCV2 in Large-Scale Pig Farms in China Affected by African Swine Fever from 2018-2021

“…The kidney also showed a high positive rate of PCV2, which is consistent with previous reports (Kleymann et al, 2020), and high levels of PCV can induce PDNS. In addition, the high positive rate also was revealed in immune organs such as the liver, spleen, and lymph nodes, which is associated with the frequent invasion of immune organs by PCV2 (Shi, Hou, & Liu, 2021), and viremia may occur in severe cases (Correa-Fiz et al, 2020;Lopez-Lorenzo et al, 2021). PCV2 also was detected in the intestines and stomach, which is indicative of gastrointestinal infection with circovirus, and agrees with recent reports (G. P. Liu et al, 2019;Yang et al, 2020).…”

Particulate Matter in Swine Barns: A Comprehensive Review

“…For IAV, the occurrence frequency of positive samples ranged from 0% [summer samples in Anderson et al (2016)] to 68% [calculated from Corzo et al (2013)] and the measured airborne concentration was up to 1.25×10 6 copies m -3 (Neira et al, 2016). For PCV2, positive samples ranged from 25% (López-Lorenzo et al, 2021) to 91% (Verreault et al, 2010) in occurrence frequency and from 10 3 (Rodríguez de Evgrafov et al, 2013) to 2.42×10 7 copies m -3 (López-Lorenzo et al, 2021) in airborne concentrations. For PSV, only one study was available (Naide et al, 2018) in which all bioaerosol samples were found PSVpositive and the airborne concentration ranged from 5.25×10 4 to 1.78×10 8 copies m -3 .…”

“…Because of the small volume of bioaerosol samples (and accordingly fewer viral genomic materials), airborne viral detection was less sensitive and required a greater cycle threshold (Ct) than the analysis of other samples (Refer to Section 4.4.2). However, bioaerosol measurement still showed its great potential as it yielded only slightly lower positive counts than pig oral secretion or environmental swab samples (Anderson et al, 2016;Neira et al, 2016;López-Lorenzo et al, 2021), enabled earlier viral detection than blood sample analysis (López-Lorenzo et al, 2021), and was able to reflect the onset, peak, and disappearance of a viral infection episode (Vilata et al, 2019;López-Lorenzo et al, 2021).…”

“… Wet cyclones were the most prevalent bioaerosol samplers in the literature (Corzo et al, 2013;Brito et al, 2014;Priebe et al, 2015;Neira et al, 2016;Naide et al, 2018;Stein et al, 2018;Wenke et al, 2018;Bell, 2020), followed by filter samplers (Verreault et al, 2010;O'Brien and Nonnenmann, 2016;Stein et al, 2018;Bell, 2020;López-Lorenzo et al, 2021) and impingers (Rodríguez de Evgrafov et al, 2013;Anderson et al, 2016). The selected filters include gelatin filters (Verreault et al, 2010;López-Lorenzo et al, 2021) and PTFE filters (O'Brien and Nonnenmann, 2016;Bell, 2020). Non-viable cascade impactors were used to study the size distribution of viral particles, with samples collected on aluminum plates (Alonso et al, 2017).…”

“…For liquid samples acquired from wet cyclones and impingers, they can be directly submitted for DNA or RNA extraction. For solid samples derived from filter samplers or sedimentation plates, they can be extracted into a liquid solution and optionally further pelleted before extraction (Verreault et al, 2010;O'Brien and Nonnenmann, 2016;López-Lorenzo et al, 2021). No extraction kit information is available for DNA viruses.…”