Pathogenic characterization of porcine reproductive and respiratory syndrome virus of Indian origin in experimentally infected piglets

Abstract

Porcine reproductive and respiratory syndrome (PRRS) is an economically important transboundary viral disease of pigs confronting the swine industry worldwide. This study was aimed to assess the pathogenic potential of PRRS virus belonging to genotype 2 that emerged in India in 2013. Nine 6-week-old piglets were inoculated intranasally with 2 × 10 TCID /ml of PRRSV (Ind-297221/2013). Three piglets were kept as uninfected controls. Blood and nasal swabs were collected daily up to 7 days post-infection (dpi) and on alternate days subsequently. Piglets were necropsied for tissue sample collection either on death or after euthanasia on 7, 14 or 21 dpi (one uninfected control and three PRRSV-infected piglets per interval). The virus caused high fever, typical blue ear, weight loss, respiratory distress, diarrhoea and leucopenia between 2 and 8 dpi. Two infected piglets died (on 3 and 17 dpi) during the course of study. The presence of virus in serum and nasal secretion was observed up to 19 and 17 dpi, respectively, with the maximum load between 4 and 7 dpi. Seroconversion started 6 dpi and the mean PRRSV antibody titre reached up to 640 by 21 dpi. Virus load was highest in tonsils at all the intervals, whereas in spleen and lymph nodes load was higher in later intervals. Major microscopic lesions in PRRSV-infected piglets included moderate to severe interstitial pneumonia, lymphoid depletion in tonsils and lymph nodes (cystic), thymic atrophy, reactive hyperplasia followed by lymphoid depletion in spleen. PRRSV antigen was consistently demonstrated by immunoperoxidase test in the lungs, spleen, tonsils and lymph nodes. Antigen distribution was more widespread on 7 and 14 dpi than on 21 dpi. The findings establish that the Indian PRRSV is highly pathogenic to piglets.

Porcine reproductive and respiratory syndrome virus impacts on gut microbiome in a strain virulence‐dependent fashion

“…Since 2006, the heterogeneity among PRRSV strains has been reinforced by the identification of virulent strains in Asia (PRRSV‐2) and Europe (PRRSV‐1) (Tian et al ., 2007 ; Karniychuk et al ., 2010 ). These virulent strains induce high fever and severe respiratory problems complicated with secondary bacterial co‐infections, leading to an increase in morbidity and mortality rates (Tian et al ., 2007 ; Karniychuk et al ., 2010 ; Senthilkumar et al ., 2018 ; Rodríguez‐Gómez et al ., 2019 ). Among several virulent PRRSV‐1 strains, the subtype 3 PRRSV‐1 Lena strain is considered to be the prototype (Karniychuk et al ., 2010 ; Morgan et al ., 2013 ; Frydas et al ., 2015 ; Sinn et al ., 2016 ; Canelli et al ., 2017 ; Stadejek et al ., 2017 ).…”

Isolation and molecular characterization of GP5 glycoprotein gene of Betaarterivirus suid 2 from Mizoram, India

“…PAM cells have been used extensively for the isolation of Betaarterivirus suid 2 in different outbreaks [1,33]. However, a cell line derived from MA-104 cells expressing high and stable porcine CD163 named MARC-145 is a very suitable cell line for isolation of the North American genotype of the virus and is also used for vaccine production [18,33,34,39]. A newly derived cell line SJPL from monkey origin was found to be permissive for this virus and reported to be an additional tool to study in vitro pathogenesis [27].…”

“…Since its first occurrence in 1987 in North America and 1991 in Europe, the disease has spread to Southeast Asian countries [16] and was introduced to India in 2013 in Mizoram [29]. The emergence of highly pathogenic strain and its rapid spread in Asian countries become a major concern in pig husbandry practice in this region as diseased animals exhibit severe respiratory distress, pneumonia, and a series of reproductive disorders in sows, like late-term abortion, premature farrowing, an increased number of stillborn piglets including high mortality by highly pathogenic strains [1][2][3][32][33][34]. The disease is caused by Betaarterivirus suid 1 (European type) and Betaarterivirus suid 2 (North American type) of the subgenus Eurpobartevirus and Ampobartevirus respectively under the genus Betaarterivirus of the subfamily Variarterivirinae of the family Arteriviridae in the order Nidovirales.…”

“…However, both species are genetically diverse (60% homology) [23] and the North American type is mostly circulating in this region. The virus is having a selective tropism for porcine alveolar macrophages (PAM) expressing CD163 and sialoadhesin virus receptors and can be best isolated in primary PAM culture [1,33,34] as well as MARC-145 cells expressing the receptors [18,33,34]. The virus genome is around 15.1-15.5 kb having ten overlapping open reading frames (ORF) [7].…”

Lymph-Node-Sampler-Based Nucleic Acid Detection Helps to Diagnose and Control African Swine Fever in Pig Production

“…Lymph nodes were collected by dissecting for viral load measurements in many studies (Palya et al, 2018;Senthilkumar et al, 2018;Liu et al, 2019). Slaughter is unavoidable to get the lymph nodes, which is unsafe and complicated.…”