Evidence of infectivity of airborne porcine epidemic diarrhea virus and detection of airborne viral RNA at long distances from infected herds

Abstract

Porcine epidemic diarrhea virus (PEDV) spread rapidly after being diagnosed in the USA in April 2013. In this study we assessed whether PEDV could become airborne and if so, whether the virus was infectious. Air samples were collected both from a room containing experimentally infected pigs and at various distances from the outside of swine farms experiencing acute PEDV outbreaks. Results indicated presence of infectious PEDV in the air from experimentally infected pigs and genetic material of PEDV was detected up to 10 miles downwind from naturally infected farms. Airborne transmission should be considered as a potential route for PEDV dissemination.

Porcine epidemic diarrhea virus: current insights

“…Airborne viable PEDV virus has been detected in air samples from an isolation room with infected pigs and PEDV RNA was detected by real-time polymerase chain reaction (RT-PCR) in air up to 10 miles downwind from an infected site. 92 The findings that the direction of disease spread correlated qualitatively with wind direction reported by Beam et al 93 provide support to the hypothesis of airborne PEDV spread. However, this study did not provide a definitive assessment of airborne spread of the virus; more studies should be conducted to assess the possibility of airborne transmission.…”

Evaluation of two real-time polymerase chain reaction assays for Porcine epidemic diarrhea virus (PEDV) to assess PEDV transmission in growing pigs

“…The gN and gS real-time RT-PCR PEDV assays have been demonstrated to be very effective for the detection and differentiation of field and vaccine strains of PEDV. 1,2,17 The primers and probes for the gN 16 (UMVDL, 2013, http:// www.cvm.umn.edu/sdec/prod/groups/cvm/@pub/@cvm/@ sdec/documents/content/cvm_content_446628.pdf ) and gS (UMVDL, 2013) assays have previously been shown to be specific for PEDV, with no cross-reaction with other diarrheacausing viruses. The goal of our study was to evaluate the gN and gS real-time RT-PCR assays to detect an acute PEDV infection in experimentally infected pigs.…”

“…Primers and a probe, labeled at the 5'-end with the reporter dye 6-carboxyfluorescein (FAM) and at the 3′-end with the 3′-quencher BHQ1, were targeted to the partial gS gene 17,20,23 at nucleotides 1910-2021, which yielded a 111-bp DNA fragment. 2 Primers and a probe, labeled at the 5′-end with FAM and at the 3′-end with BHQ1, for gN real-time RT-PCR were targeted to the gN gene at nucleotides 941-1028, which yielded a 87-bp DNA fragment. The PED_N_Forward primer sequence was 5′-GAATTCCCAAGGGCGAAAAT-3′, the PED_N_Reverse primer sequence was 5′-TTTTCGACAAATTCCGCATCT-3′, and the PED_N_probe sequence was FAM-CGTAGCAGCTT GCTTCGGACCCA-BHQ.…”

“…This protocol differs from the University of Minnesota Veterinary Diagnostic Laboratory where reverse transcription is conducted at 48°C. 2 Samples were run in duplicate. A run was considered valid when the following 5 criteria were met: 1) slopes of both standard curves were above −4 (PCR efficiency >77.8%); 2) correlation coefficient (r 2 ) of at least 4 relevant data points above 0.99; 3) routinely included no-template control was not amplified; 4) the positive assay control was detectable; and 5) the negative assay control was not detected within the standard curve.…”

Porcine gastroenteric viruses: pathogenesis and protection

“…In addition, a correlation between the severity of the infection and the innate immune responses has been observed. In young piglets NK cell activity andits interferon (IFN)-γ production were lower than those in weaned pigs (Annamalai et al, 2015).…”