Intense Innate Immune Responses and Severe Metabolic Disorders in Chicken Embryonic Visceral Tissues Caused by Infection with Highly Virulent Newcastle Disease Virus Compared to the Avirulent Virus: A Bioinformatics Analysis

Abstract

The highly virulent Newcastle disease virus (NDV) isolates typically result in severe systemic pathological changes and high mortality in Newcastle disease (ND) illness, whereas avirulent or low-virulence NDV strains can cause subclinical disease with no morbidity and even asymptomatic infections in birds. However, understanding the host’s innate immune responses to infection with either a highly virulent strain or an avirulent strain, and how this response may contribute to severe pathological damages and even mortality upon infection with the highly virulent strain, remain limited. Therefore, the differences in epigenetic and pathogenesis mechanisms between the highly virulent and avirulent strains were explored, by transcriptional profiling of chicken embryonic visceral tissues (CEVT), infected with either the highly virulent NA-1 strain or the avirulent vaccine LaSota strain using RNA-seq. In our current paper, severe systemic pathological changes and high mortality were only observed in chicken embryos infected with the highly virulent NA-1 strains, although the propagation of viruses exhibited no differences between NA-1 and LaSota. Furthermore, virulent NA-1 infection caused intense innate immune responses and severe metabolic disorders in chicken EVT at 36 h post-infection (hpi), instead of 24 hpi, based on the bioinformatics analysis results for the differentially expressed genes (DEGs) between NA-1 and LaSota groups. Notably, an acute hyperinflammatory response, characterized by upregulated inflammatory cytokines, an uncontrolled host immune defense with dysregulated innate immune response-related signaling pathways, as well as severe metabolic disorders with the reorganization of host–cell metabolism were involved in the host defense response to the CEVT infected with the highly virulent NA-1 strain compared to the avirulent vaccine LaSota strain. Taken together, these results indicate that not only the host’s uncontrolled immune response itself, but also the metabolic disorders with viruses hijacking host cell metabolism, may contribute to the pathogenesis of the highly virulent strain in ovo.

Time-Course Transcriptome Landscape of Bursa of Fabricius Development and Degeneration in Chickens

“…To validate the accuracy of RNA-seq, we selected RT-PCR for 16 genes, of which SPP1 [21][22][23], CTNNB1 [24], BMF [25,26], IL10 [27,28], TUBB3 [29], TUBA8 [30], TUBA3E [31], LMNB2 [32,33], MYL9 [34,35], LITAF [36], CDH11 [37,38], MYBL1 [39] and TRAIL [40,41] were shown to be significantly associated with cell proliferation and apoptosis. In addition, BF2, B2M and BF1 are important members of the MHC, which has been shown to be significantly associated with the immune competence of the organism [42][43][44]. The qRT-PCR and RNA-seq results were consistent (Figure 7).…”

Long Non-Coding RNA Analysis: Severe Pathogenicity in Chicken Embryonic Visceral Tissues Infected with Highly Virulent Newcastle Disease Virus—A Comparison to the Avirulent Vaccine Virus

“…The handing and tissue collection procedures for chicken embryos were described in our previous work [12]. In brief, sixty-four 10-day-old chicken embryos were randomly allocated into two groups, one with a single dose of 7 × 10 3 TCID50 of either virulent strain NA-1 (n = 32) and another with an avirulent vaccine strain called LaSota (n = 32).…”

“…Total RNA extraction from chicken embryo visceral tissues (CEVTs) without any modification was previously described in detail in our study [12]. Thereafter, the qualified RNA samples for library construction underwent tRNA and rRNA removal treatment before cDNA library preparation to meet the specified requirements.…”

Comparative Biological Pathotyping of Newcastle Disease Virus Sub-genotypes VIIg, VIIh, and VIIi in Specific Pathogen Free (SPF) Chickens

“…As a result of the infection of the NDV, causing lesions in the lymphoreticular organs, indicate that the ability to fight infection is impaired (Etriwati et al, 2017). The virulent NDV activated the innate immune system and disrupted the metabolism causing pathological changes in the immune system (Cheng et al, 2022). Current velogenic strain NDV infection also caused pathological changes in lymphoid organs such as the thymus, spleen, and bursa of Fabricius (Nooruzzaman et al, 2022).…”