Liver Transudate, a Potential Alternative to Detect Anti-Hepatitis E Virus Antibodies in Pigs and Wild Boars (Sus scrofa)

Abstract

In recent years, cases of hepatitis E virus (HEV) infection have increased in Europe in association with the consumption of contaminated food, mainly from pork products but also from wild boars. The animal’s serum is usually tested for the presence of anti-HEV antibodies and viral RNA but, in many cases such as during hunting, an adequate serum sample cannot be obtained. In the present study, liver transudate was evaluated as an alternative matrix to serum for HEV detection. A total of 125 sera and liver transudates were tested by enzyme-linked immunosorbent assay at different dilutions (1:2, 1:10, 1:20), while 58 samples of serum and liver transudate were checked for the presence of HEV RNA by RT-qPCR. Anti- HEV antibodies were detected by ELISA in 68.0% of the serum samples, and in 61.6% of the undiluted transudate, and in 70.4%, 56.8%, and 44.8% of 1:2, 1:10, or 1:20 diluted transudate, respectively. The best results were obtained for the liver transudate at 1:10 dilution, based on the Kappa statistic (0.630) and intraclass correlation coefficient (0.841). HEV RNA was detected by RT-qPCR in 22.4% of the serum samples and 6.9% of the transudate samples, all samples used for RT-qPCR were positive by ELISA. Our results indicate that liver transudate may be an alternative matrix to serum for the detection of anti-HEV antibodies.

Hepatitis E Virus in the Iberian Peninsula: A Systematic Review

“…might have a protective effect on HEV acquisition in swine (Antonio Rivero-Juarez et al, 2020 ), with a follow up study performed by the same group showing that the existence of external enteroparasites is associated with a protective effect on the likelihood of obtaining HEV, while internal enteroparasites appear to have the opposing effect by promoting HEV contamination (Rivero-Juárez et al, 2022 ). Another study evidenced that liver transudate could be used for HEV RNA detection (Navarro et al, 2020 ). A study reported HEV RNA in 27.9% (11/29) of Hyalomma lusitanicum ticks feeding on wild boars and in 34.5% (10/29) of wild boar serum samples, further typing as HEV-3 subgenotype 3f (Antonio Rivero-Juarez et al, 2021 ).…”

“…The second and last nationwide study in pig sera samples detected IgG anti-HEV in 73.3% (33/45) of animals (García et al, 2020 ). In a study that aimed to compare liver transudate with serum for the detection of antibodies in pigs and wild boars, anti-HEV was detected in 68% (85/125) of sera samples and in 61.6% (77/125) in liver transudate samples, concluding that liver transudate could be used as an alternative matrix to serum for the detection of anti-HEV antibodies (Navarro et al, 2020 ). A longitudinal long-term survey of HEV exposure in wild boar reported IgG anti-HEV in 46.7% (327/700) of animals (Barroso et al, 2021 ).…”

“…Likewise, many studies from Spain have confirmed the high circulating of HEV-3 in swine populations in all the country, in large or family flocks, and in all age groups with several studies reporting low to very high detection rates in pigs (Berto et al, 2012a , 2012b ; Casas et al, 2011a , 2011b ; Clemente-Casares et al, 2003 ; Deus et al, 2007 ; Deus et al, 2008a , 2008b ; Deus et al, 2008a , 2008b ; Fernández-Barredo et al, 2006 , 2007 ; García et al, 2020 ; Kukielka et al, 2016 ; Lopez-Lopez et al, 2018 ; Martín et al, 2007 ; Navarro et al, 2020 ; Risalde et al, 2020 ; Riveiro-Barciela et al, 2015 ; Antonio Rivero-Juarez et al, 2020 ; Seminati et al, 2008 ). Concerning anti-HEV antibody detection, similar results have been observed when comparing them to HEV RNA in Spain (Casas et al, 2009 , 2011a , 2011b ; Clemente-Casares et al, 2003 ; Deus et al, 2008a , 2008b ; García et al, 2020 ; Jiménez De Oya et al, 2011 ; Kukielka et al, 2016 ; Martín et al, 2007 ; Navarro et al, 2020 ; Peralta et al, 2009a , 2009b ; Pina et al, 2000 ; Seminati et al, 2008 ). Interestingly, one study reported swine HEV-3 infection dynamics in a longitudinal survey conducted in farrow-to-finish farms showing the presence of HEV RNA in all stage groups (Casas et al, 2011a ).…”

“…This data is alarming since Spain is considered the biggest producer of pork meat and pork meat products in Europe (MAPA, 2021 ). HEV-3 circulation has also been observed in wild boars from Spain, with virus detection rate ranging from 1 to 37.9% (Caballero-Gómez et al, 2019a ; de Deus et al, 2008a , 2008b ; Kukielka et al, 2016 ; Navarro et al, 2020 ; Risalde et al, 2017 , 2022 ; Antonio Rivero-Juarez et al, 2018c , 2020 ) and HEV seroprevalence varying between 5.2 and 62.8% (Barroso et al, 2021 ; Boadella et al, 2012 ; Caballero-Gómez et al, 2019a ; Deus et al, 2008a , 2008b ; Kukielka et al, 2016 ; Pina et al, 2000 ; María A. Risalde et al, 2017 ; Wang et al, 2019 ). In general, HEV-3 is highly prevalent in swine populations throughout the Iberian Peninsula posing a potential high risk of zoonotic transmission through the consumption of raw or undercooked pork meat or pork derived products.…”

Research progress on detection techniques for point-of-care testing of foodborne pathogens

“…Enzyme-linked immunosorbent assay (ELISA) is a sensitive and specific analytical biochemical method that can be used for the detection and quantitative or qualitative analysis of analytes without requiring sophisticated or expensive equipment ( Ferone et al, 2020 ; Nath et al, 2020 ; Rani et al, 2021 ; Kotsiri et al, 2022 ). At present, although traditional ELISA is widely used in scientific research and testing institutions and is the ideal method for the detection of viruses and antibodies ( Leva-Bueno et al, 2020 ; Navarro et al, 2020 ; Xiao et al, 2021 ), this traditional method is time-consuming and also requires skilled operation techniques and sophisticated instruments ( Luo et al, 2020a ; Razmi et al, 2020 ; Huang et al, 2022 ). So the researchers changed the traditional approach.…”