Characterization of Pseudorabies Virus Associated with Severe Respiratory and Neuronal Signs in Old Pigs

Abstract

Pseudorabies virus (PRV) represents a leading threat to the global pig industry. Generally, pigs exhibit a pronounced age resistance against PRV, and the virus generally does not cause severe clinical signs and even death in old pigs. However, we characterized two PRV strains (HeN21 and HuB20) associated with severe respiratory and neuronal signs in old pigs. Among these two strains, HeN21 was isolated from the tonsil of a 24-week-old pig that died from severe neuronal and respiratory signs in a PRV-outbreak farm where a commercial PRV attenuated vaccine developed based on a PRV variant was used; while, HuB20 was isolated from the lung and lymph node of a 20-week-old with symptoms in another farm where Bartha-K61 vaccine was used. In vitro evaluations in different cell models demonstrated that HeN21 and HuB20 led to similar cytotoxic effects to those caused by PRV variants on PK-15, Vero, and SK-N-SH cells after 30 hours of inoculation. However, HeN21 possessed a higher titer than the other PRV variants from the first to the fifth passage on PK-15 cells and induced plaques with larger size. In vivo assessments in mouse and fattening pig models showed that inoculations of HeN21 and HuB20 caused higher morbidity and mortality and severe pathological damages in tested animals. In particular, challenge of HeN21 led to severe respiratory and neuronal signs in 90-day-old pigs. These two strains displayed higher virus loads on the main organs of challenged mice and pigs. Phylogenetic analysis revealed that HeN21 and HuB20 belonged to genotype II. In addition, recombinant events were identified in the genomes of HeN21 and HuB20, and several events were located within genes associated with PRV virulence. Our data herein may suggest the emergence of novel PRV strains in China.

Microglia play an important role in PRV infection-induced immune responses of the central nervous system

“…Three pigs died: two on day 7 and one on day 10 post-infection. One pig had difficulty eating on day 4 post-infection [ 24 ]. Histological examination revealed typical pathological changes in viral encephalitis in brain tissues, including neuronal degeneration and necrosis (green arrow), glial nodule formation via astrocyte proliferation (yellow arrow), and a typical “perivascular cuffing” phenomenon characterized by a large number of infiltrating inflammatory cells surrounding the blood vessels (red arrow), which were visible throughout the brain (Fig.…”

Microglia Play an Important Role in PRV Infection-Induced Immune Responses of the Central Nervous System

“…Three pigs died: two on day 7 and one on day 10 post-infection. One pig had di culty eating on day 4 post-infection (24). Histological examination revealed typical pathological changes in viral encephalitis in brain tissues, including neuronal degeneration and necrosis (green arrow), glial nodule formation via astrocyte proliferation (yellow arrow), and a typical "perivascular cu ng" phenomenon characterized by a large number of in ltrating in ammatory cells surrounding the blood vessels (red arrow), which were visible throughout the brain (Fig.…”

Assessment of different factors on the influence of glass wool concentration for detection of main swine viruses in water samples

“…RNAs were transcribed into cDNA by a reverse transcription reagent kit (RRA036, Takara, Japan) immediately. The detection of viral nucleic acids was performed using qPCR (CF96X; Bio-rad, Hercules, CA, USA), following the primers ( Table S1 ) and protocols described previously ( Chen et al, 2023 ; Guo et al, 2016 ; Lin et al, 2020 ). The standard curve was established as follows: a slightly longer gene sequence than the target fragment was designed, usually around 300–600 bp, and a specific primer was designed for PCR amplification and Gel recovery.…”