Molecular detection of porcine reproductive and respiratory syndrome virus, porcine circovirus 2 and hepatitis E virus in oral fluid compared to their detection in faeces and serum

Abstract

Background: Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), Porcine Circovirus Type 2 (PCV2) and Hepatitis E virus (HEV) are common and economically important viral disease causative agents detected in pig oral fluid (OF), faeces and serum at some infection stages. The purpose of this study was to detect PRRSV, PCV2 and HEV on six pig farms to determine which of the three sample types, OF, faeces or serum is appropriate for the diagnosis of these viruses in different pig categories. The following pig categories were included: 5 weeks-old (w/o), 7 w/o, 9 w/o, 11 w/o weaners, fatteners and breeding sows. Pursuant to the preliminary detection of each pathogen at the selected farms, OF samples, faeces, serum pools and 10 individual sera were examined, using PCR, for each age category. If any of the viruses were found in pools of faeces and OF, then faeces and OF from positive farms were tested separately for each pig category. The viral nucleic acids were detected using RT-PCR, PCR and real-time RT-PCR, for PRRSV, PCV2 and HEV respectively. Results: PRRSV and HEV were detected on one farm and PCV2 on three others, positive results being more often obtained from the OF than from the faeces of the same animals. Ten individual serum samples from pigs from the same group of animals were also tested. The viruses were detected in almost all individual sera and OF in the same pig category with some exceptions: PRRSV was detected in the OF of fatteners but was absent in their sera; on Farm 2, PCV2 was detected in sera of 11 w/o pigs and fatteners but absent in group samples of their OF and, vice versa, in case of 9 w/ o animals; HEV was detected in the OF of the youngest, 5 w/o weaners and absent in sera of the same age group. Conclusions: The primary finding of the study is that OF is a welfare-friendly, non-invasive and highly efficient matrix for pathogen detection, thus evidencing the usefulness of pig OF as a matrix in which each of the three viruses considered can be detected with the highest probability.

Virological and Histopathological Findings in Boars Naturally Infected With Porcine Reproductive and Respiratory Syndrome Virus Type 1

“…The pronounced genetic differences among strains have resulted in the current classification of the virus within the new genus Betaarterivirus (family Arteriviridae , order Nidovirales ) as two distinct viral species, Betaarterivirus suid 1 (for PRRSV-1; subgenus Eurpobartevirus ) and Betaarterivirus suid 2 (for PRRSV-2; subgenus Ampobartevirus ) ( Brinton et al, 2018 ). Infected pigs excrete PRRSV through respiratory aerosols, saliva, urine, faeces, and semen ( Christopher-Hennings et al, 1995b , 2001 ; Wills et al, 2003 ; Plut et al, 2020 ). Venereal transmission of PRRSV by artificial insemination has been documented in experimental studies ( Swenson et al, 1994 ; Gradil et al, 1996 ; Nielsen et al, 1997 ; Prieto et al, 1997 ; Guérin and Pozzi, 2005 ) and in the field ( Yaeger, 1993 ; Nathues et al, 2016 ).…”

Evaluation of Non-Invasive Sampling Methods for Detection of Hepatitis E Virus Infected Pigs in Pens

“…One mL of supernatant was transferred to a micronic tube and stored at −80 °C [ 26 ]. OF samples were centrifuged for 10 min at 2000× g and the supernatant was stored at −80 °C [ 18 ]. One week later, all samples were transported on dry ice for an hour to another laboratory, frozen at −80 °C again, and used for RNA extraction and detection that same week.…”

“…Pigs shed HEV in faeces and possibly urine [ 16 ] and HEV has been found in salivary glands [ 17 ], so oral fluids, boot socks and faecal droppings seem the most promising methods to replace invasive sampling. Oral fluid samples can be used to detect HEV RNA or antibodies [ 18 , 19 , 20 ]. Boot socks are mainly used to detect Salmonella spp., in both poultry and pig farming [ 21 , 22 ] and have also been shown to be useful for HEV RNA detection [ 23 ].…”

Haematological Profiles of Pigs on Different Farms Reflect Their Health Status

“…The group OF and faeces samples were collected to determine the health status of the herd and to con rm the presence of PRRSV, HEV and PCV2. The group OF and faeces samples were collected as described in the study by Plut et al (2020) [39]. A total of 36 OF samples and 36 faeces samples were collected and examined from each of the animal categories on each of the six farms.…”

“…A total of 36 OF samples and 36 faeces samples were collected and examined from each of the animal categories on each of the six farms. Previously described PCR, RT-PCR and qRT-PCR protocols were used to detect PCV2, PRRSV and HEV [39].…”