Subversion of cellular stress responses by poxviruses

Unveiling Oxidative Stress-Induced Genotoxicity and Its Alleviation through Selenium and Vitamin E Therapy in Naturally Infected Cattle with Lumpy Skin Disease

Lumpy skin disease (LSD) is a contagious infection of cattle caused by a virus of the Poxviridae family, genus Capripoxvirus. In Pakistan, recent outbreaks have resulted in significant nationwide mortality and economic losses. A 20-day prospective cohort study was performed on sixty infected cattle with the aim to evaluate LSD-induced oxidative stress's genotoxic role and to determine the ameliorative effect of antioxidant therapy using principal component analysis (PCA) and a multivariable ordinal logistic regression model. LSDV was identified from scab samples and nodular lesions using RPO30-specific gene primers. The infected cattle were divided into control and treated groups. The animals were observed initially and finally on day 20 to evaluate the homeostatic, oxidative, and genotoxic changes. The animals in the treated group were administered a combination of selenium (Se) and vitamin E at the standard dose rate for five consecutive days. A substantial (p < 0.05) improvement in the hematological indices was observed in the treated group. The treated group also showed a significant (p < 0.05) reduction in levels of serum nitric oxide (NO) and malondialdehyde (MDA) post-therapy. The PCA at the final sampling data of the treated group showed that Principal Component (PC1 eigenvalue 1.429) was influenced by superoxide dismutase (SOD; 0.3632), catalase (CAT; 0.2906), and glutathione (GSH; 0.0816) and PC2 (eigenvalue 1.200) was influenced by CAT (0.4362), MDA (0.2056), and NO (0.0693). A significant correlation between serum NO (76%) and MDA levels (80%) was observed with genetic damage index (GDI) scores. The ordinal logistic regression model regarding the use of antioxidant therapy revealed 73.95-times (95%CI; 17.36-314.96) improvement in the GDI in treated animals. The multivariable ordinal logistic regression showed that each unit increase in NO and MDA resulted in a 13% increase in genotoxicity in infected individuals. In conclusion, our study revealed that LSD-induced oxidative stress and lipid peroxidation product causes genotoxicity in affected animals. Furthermore, the combined Se and vitamin E therapy significantly alleviated oxidative stress and genotoxicity in LSD-affected cattle.

Manipulation of unfolded protein response by zoonotic vaccinia virus strains Guarani P1 and Passatempo

The replicative success of vaccinia virus (VACV) depends on its ability to subvert host functions. Poxviruses multiplication and maturation are closely associated with the endoplasmic reticulum (ER) and its membranes. This organelle responds to disturbances caused by the accumulation of misfolded proteins, leading to processing of these proteins or even programmed cell death through the unfolded protein response (UPR). Several studies show that different viruses can activate UPR pathway components and negatively modulate others. Here, we investigate the effects of infections by zoonotic VACV strains from Brazil, Guarani P1 virus (GP1V) and Passatempo virus (PSTV), in the activation of UPR pathway sensors. We observed translocation of ATF6 to the nucleus as well as transcriptional increase after GP1V, PSTV, and reference strain Western Reserve (WR) infection. XBP1 processing appears to be negatively modulated after VACV infection; however, inhibition of the inositol-requiring enzyme 1 (IRE1) kinase domain led to a reduction in plaque sizes for these viruses. The absence of PKR-like endoplasmic reticulum kinase (PERK) has an impact on the plaque phenotype of GP1V, PSTV viruses, as well as for the prototypical strain WR. These results indicate that the VACV manipulates the three arms of the UPR path differently to ensure replicative success.

Vaccinia virus induces endoplasmic reticulum stress and activates unfolded protein responses through the ATF6α transcription factor

BACKGROUND

Cell responses to different stress inducers are efficient mechanisms that prevent and fight the accumulation of harmful macromolecules in the cells and also reinforce the defenses of the host against pathogens. Vaccinia virus (VACV) is an enveloped, DNA virus, belonging to the Poxviridae family. Members of this family have evolved numerous strategies to manipulate host responses to stress controlling cell survival and enhancing their replicative success. In this study, we investigated the activation of the response signaling to malformed proteins (UPR) by the VACV virulent strain-Western Reserve (WR)-or the non-virulent strain-Modified Vaccinia Ankara (MVA).

METHODS

Through RT-PCR RFLP and qPCR assays, we detected negative regulation of XBP1 mRNA processing in VACV-infected cells. On the other hand, through assays of reporter genes for the ATF6 component, we observed its translocation to the nucleus of infected cells and a robust increase in its transcriptional activity, which seems to be important for virus replication. WR strain single-cycle viral multiplication curves in ATF6α-knockout MEFs showed reduced viral yield.

RESULTS

We observed that VACV WR and MVA strains modulate the UPR pathway, triggering the expression of endoplasmic reticulum chaperones through ATF6α signaling while preventing IRE1α-XBP1 activation.

CONCLUSIONS

The ATF6α sensor is robustly activated during infection while the IRE1α-XBP1 branch is down-regulated.

Genomic associations with poxvirus across divergent island populations in Berthelot's pipit

Understanding the mechanisms and genes that enable animal populations to adapt to pathogens is important from an evolutionary, health and conservation perspective. Berthelot's pipit (Anthus berthelotii) experiences extensive and consistent spatial heterogeneity in avian pox infection pressure across its range of island populations, thus providing an excellent system with which to examine how pathogen-mediated selection drives spatial variation in immunogenetic diversity. Here we test for evidence of genetic variation associated with avian pox at both an individual and population-level. At the individual level, we find no evidence that variation in MHC class I and TLR4 (both known to be important in recognising viral infection) was associated with pox infection within two separate populations. However, using genotype-environment association (Bayenv) in conjunction with genome-wide (ddRAD-seq) data, we detected strong associations between population-level avian pox prevalence and allele frequencies of single nucleotide polymorphisms (SNPs) at a number of sites across the genome. These sites were located within genes involved in cellular stress signalling and immune responses, many of which have previously been associated with responses to viral infection in humans and other animals. Consequently, our analyses indicates that pathogen-mediated selection may play a role in shaping genomic variation among relatively recently colonised island bird populations and highlights the utility of genotype-environment associations for identifying candidate genes potentially involved in host-pathogen interactions.

Targeting unfolded protein response: a new horizon for disease control

Unfolded protein response (UPR) is an evolutionarily conserved pathway triggered during perturbation of endoplasmic reticulum (ER) homeostasis in response to the accumulation of unfolded/misfolded proteins under various stress conditions like viral infection, diseased states etc. It is an adaptive signalling cascade with the main purpose of relieving the stress from the ER, which may otherwise lead to the initiation of cell death via apoptosis. ER stress if prolonged, contribute to the aetiology of various diseases like cancer, type II diabetes, neurodegenerative diseases, viral infections etc. Understanding the role of UPR in disease progression will help design pharmacological drugs targeting the sensors of signalling cascade acting as potential therapeutic agents against various diseases. The current review aims at highlighting the relevance of different pathways of UPR in disease progression and control, including the available pharmaceutical interventions responsible for ameliorating diseased state via modulating UPR pathways.