Biology of Variola Virus.

Variola virus is an anthroponotic agent that belongs to the orthopoxvirus family. It is an etiological agent of smallpox, an ancient disease that caused massive mortality of human populations. Twentieth century has witnessed the death of about 300 million people due to the unavailability of an effective vaccine. Early detection is the primary strategy to prevent an outbreak of smallpox. Variola virus forms the characteristic pus-filled pustules and centrifugal rash distribution in the infected patients while transmission occurs mainly through respiratory droplets during the early stage of infection. No antiviral drugs are approved for variola virus till date. Generation of first-generation vaccines helped in the eradication of smallpox which was declared by the World Health Organization.

VIP interneurons in sensory cortex encode sensory and action signals but not direct reward signals.

Vasoactive intestinal peptide (VIP) interneurons in sensory cortex modulate sensory responses based on global exploratory behavior and arousal state, but their function during non-exploratory, goal-directed behavior is not well understood. In particular, whether VIP cells are activated by sensory cues, reward-seeking actions, or directly by reinforcement is unclear. We trained mice on a Go/NoGo whisker touch detection task that included a delay period and other features designed to separate sensory-evoked, action-related, and reward-related neural activity. Mice had to lick in response to a whisker stimulus to receive a variable-sized reward. Using two-photon calcium imaging, we measured ΔF/F responses of L2/3 VIP neurons in whisker somatosensory cortex (S1) during behavior. In both expert and novice mice, VIP cells were strongly activated by whisker stimuli and goal-directed actions (licking), but not by reinforcement. VIP cells showed somatotopic whisker tuning that was spatially organized relative to anatomical columns in S1, unlike lick-related signals which were spatially widespread. In expert mice, lick-related VIP responses were suppressed, not enhanced, when a reward was delivered, and the amount of suppression increased with reward size. This reward-related suppression was not seen in novice mice, where reward delivery was not yoked to licking. These results indicate that besides arousal and global state variables, VIP cells are activated by local sensory features and goal-directed actions, but not directly by reinforcement. Instead, our results are consistent with a role for VIP cells in encoding the expectation of reward associated with motor actions.

Clinical Profile and Short-Term Outcome of Children with Acute SARS-CoV-2 Infection During the First and Second Waves of the Pandemic.

OBJECTIVES: To compare the clinical profile and short-term outcome of children admitted with acute SARS-CoV-2 infection during the first and second waves of the Coronavirus Disease (COVID-19). METHODS: This retrospective study was conducted in a tertiary care setting. A retrospective medical record review of all pediatric patients admitted with confirmed SARS-CoV-2 infection between March 2020 and September 2021 was conducted. Patients' demographic data, pre-existing comorbidities, mode of presentation, and clinical course in the hospital were noted. The outcome measures were in-hospital mortality, need for intensive care, and invasive mechanical ventilation, duration of ICU, and hospital stay. RESULTS: One thousand and twenty-four children were recruited, 592 of the first wave and 432 of the second wave. In the second wave, more children were admitted with respiratory distress (OR = 3.38) and neurological manifestations (OR = 4.61). There was a higher requirement of intensive care (OR = 4.2) and invasive mechanical ventilation (OR = 4.17). In-hospital mortality of the second wave was also increased (1.4% vs. 0.1%), but the difference was not statistically significant. Children with neurological comorbidities (OR = 8.73), malnutrition (OR = 3.01), and preterm babies (OR = 6.8) were associated with severe COVID. CONCLUSION: The clinical profile of the second wave of COVID-19 in children was different from the first wave, with more respiratory distress and neurological manifestations at presentation. In the second wave, a significant increase in the incidence of severe infections requiring ICU care was observed.

Epstein-Barr virus infection controls the concentration of the intracellular antioxidant glutathione by upregulation of the glutamate transporter EAAT3 in tumor cells.

Epstein-Barr virus or human herpesvirus 4 (EBV/HHV-4) is an omnipresent oncovirus etiologically associated with various B-cell lymphomas and epithelial cancers. The malignant transformation associated with the persistent expression of viral proteins often deregulates the host cellular machinery and EBV infection is coupled to elevated levels of reactive oxygen species. Here, we investigated the role that the glutamate transporter EAAT3 plays in regulating the antioxidant system as a protective mechanism of EBV-infected cells against the virus-induced oxidative stress. Our study demonstrated that the expression of EAAT3 was upregulated and localized to the plasma membrane in EBV latently infected and de novo EBV-infected cells. EAAT3 was regulated by the transcription factor NFAT5 in the infected cells. Membrane localized EAAT3 was found to be involved in the transportation of glutamate from the extracellular space into the cell, as EAAT3 and NFAT5 inhibitors markedly reduced the levels of intracellular glutamate levels in EBV latently infected cells. Additionally, our data demonstrated a notable decrease in the intracellular glutathione levels following treatment with an EAAT3 inhibitor. Collectively, our results suggest that upregulation of the glutamate transporter EAAT3 is an adaptation of EBV-infected cells to maintain cellular redox homeostasis against the virus-induced oxidative stress, and that this cellular balance could be therapeutically destroyed by targeting EAAT3 to impede EBV-associated cancers.

Multiplexed action-outcome representation by striatal striosome-matrix compartments detected with a mouse cost-benefit foraging task.

Learning about positive and negative outcomes of actions is crucial for survival and underpinned by conserved circuits including the striatum. How associations between actions and outcomes are formed is not fully understood, particularly when the outcomes have mixed positive and negative features. We developed a novel foraging ('bandit') task requiring mice to maximize rewards while minimizing punishments. By 2-photon Ca++ imaging, we monitored activity of visually identified anterodorsal striatal striosomal and matrix neurons. We found that action-outcome associations for reward and punishment were encoded in parallel in partially overlapping populations. Single neurons could, for one action, encode outcomes of opposing valence. Striosome compartments consistently exhibited stronger representations of reinforcement outcomes than matrix, especially for high reward or punishment prediction errors. These findings demonstrate multiplexing of action-outcome contingencies by single identified striatal neurons and suggest that striosomal neurons are particularly important in action-outcome learning.

Retinoic Acid-Inducible Gene I-Like Receptors Activate Snail To Limit RNA Viral Infections.

Retinoic acid-inducible gene I-like receptors (RLRs) are important cytosolic pattern recognition receptors (PRRs) that sense viral RNA before mounting a response leading to the activation of type I IFNs. Several viral infections induce epithelial-mesenchymal transition (EMT), even as its significance remains unclear. Here, we show that EMT or an EMT-like process is a general response to viral infections. Our studies identify a previously unknown mechanism of regulation of an important EMT-transcription factor (EMT-TF) Snail during RNA viral infections and describe its possible implication. RNA viral infections, poly(I·C) transfection, and ectopic expression of RLR components induced Snail levels, indicating that RLR pathway could regulate its expression. Detailed examination using mitochondrial antiviral signaling protein knockout (MAVS-KO) cells established that MAVS is essential in this regulation. We identified two interferon-stimulated response elements (ISREs) in the SNAI1 promoter region and demonstrated that they are important in its transcriptional activation by phosphorylated IRF3. Increasing the levels of Snail activated RLR pathway and dramatically limited replication of the RNA viruses dengue virus, Japanese encephalitis virus (JEV), and vesicular stomatitis virus, pointing to their antiviral functions. Knockdown of Snail resulted in a considerable increase in the JEV titer, validating its antiviral functions. Finally, transforming growth factor ß-mediated IFNB activation was dependent on Snail levels, confirming its important role in type I IFN activation. Thus, EMT-TF Snail is transcriptionally coregulated with type I IFN by RLRs and, in turn, promotes the RLR pathway, further strengthening the antiviral state in the cell. Our work identified an interesting mechanism of regulation of Snail that demonstrates potential coregulation of multiple innate antiviral pathways triggered by RLRs. Identification of antiviral functions of Snail also provides an opportunity to expand the sphere of RLR signaling. IMPORTANCE RLRs sense viral genomic RNA or the double-stranded RNA intermediates and trigger the activation of type I IFNs. Snail transcription factor, commonly associated with epithelial-mesenchymal transition (EMT), has been reported to facilitate EMT in several viral infections. Many of these reports are based on oncoviruses, leading to the speculation that EMT induced during infection is an important factor in the oncogenesis triggered by these infections. However, our studies reveal that EMT or EMT-like processes during viral infections have important functions in antiviral response. We have characterized a new mechanism of transcriptional regulation of Snail by IRF3 through interferon-stimulated response elements in their promoters, and this finding could have importance in nonviral contexts as well. We also identify that EMT-TF Snail promotes antiviral status of the infected cells through the RLR pathway. This study characterizes a new regulatory mechanism of activation of Snail and establishes its unidentified function in antiviral response.

Approaches and advances in the development of potential therapeutic targets and antiviral agents for the management of SARS-CoV-2 infection.

Virus onslaughts continue to spread fear and cause rampage across the world every now and then. The twenty first century is yet again witnessing a gross global pandemic, Coronavirus Disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Globally no vaccines or drug specific to COVID-19 is available. Corona viruses have been in mutual relationship with humans and other hosts over many decades though aggressive zoonotic strains have caused havoc. Zoonotic emergent corona viruses prior to SARS-COV-2 included severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV), with the former leading to aggressive infectious spread and the later with high mortality rate. Although they emerged in the early period of the twenty first century, resilient biomedical and expertise in pharmaceutical domain could not appropriate any proprietary therapeutics. Studies envisaged towards curtailing their spread employed different stages of the virus life cycle with all zoonotic coronaviruses (CoVs) sharing genomic and structural similarities. Hence the strategies against SARS-CoV and MERS-CoV could prove effective against the recent outbreak of SAR-CoV-2. The review unravels key events involved in the lifecycle of SARS-CoV-2 while highlighting the possible avenues of therapy. The review also holds the scope in better understanding a broad-spectrum antivirals, monoclonal antibodies and small molecule inhibitors against viral glycoproteins, host cell receptor, viral mRNA synthesis, RNA-dependent RNA polymerase (RdRp) and viral proteases in order to design and develop antiviral drugs for SARS-CoV-2.

Upregulation of GLS1 Isoforms KGA and GAC Facilitates Mitochondrial Metabolism and Cell Proliferation in Epstein-Barr Virus Infected Cells.

Epstein-Barr virus or human herpesvirus 4 (EBV/HHV-4) is a ubiquitous human virus associated with a wide range of malignant neoplasms. The interaction between EBV latent proteins and host cellular molecules often leads to oncogenic transformation, promoting the development of EBV-associated cancers. The present study identifies a functional role of GLS1 isoforms KGA and GAC in regulating mitochondrial energy metabolism to promote EBV-infected cell proliferation. Our data demonstrate increased expression of GLS1 isoforms KGA and GAC with mitochondrial localization in latently EBV-infected cells and de novo EBV-infected PBMCs. c-Myc upregulates KGA and GAC protein levels, which in turn elevate the levels of intracellular glutamate. Further analysis demonstrated upregulated expression of mitochondrial GLUD1 and GLUD2, with a subsequent increase in alpha-ketoglutarate levels that may mark the activation of glutaminolysis. Cell proliferation and viability of latently EBV-infected cells were notably inhibited by KGA/GAC, as well as GLUD1 inhibitors. Taken together, our results suggest that c-Myc-dependent regulation of KGA and GAC enhances mitochondrial functions to support the rapid proliferation of the EBV-infected cells, and these metabolic processes could be therapeutically exploited by targeting KGA/GAC and GLUD1 to prevent EBV-associated cancers.

Nipah Virus: Past Outbreaks and Future Containment.

Viral outbreaks of varying frequencies and severities have caused panic and havoc across the globe throughout history. Influenza, small pox, measles, and yellow fever reverberated for centuries, causing huge burden for economies. The twenty-first century witnessed the most pathogenic and contagious virus outbreaks of zoonotic origin including severe acute respiratory syndrome coronavirus (SARS-CoV), Ebola virus, Middle East respiratory syndrome coronavirus (MERS-CoV) and Nipah virus. Nipah is considered one of the world's deadliest viruses with the heaviest mortality rates in some instances. It is known to cause encephalitis, with cases of acute respiratory distress turning fatal. Various factors contribute to the onset and spread of the virus. All through the infected zone, various strategies to tackle and enhance the surveillance and awareness with greater emphasis on personal hygiene has been formulated. This review discusses the recent outbreaks of Nipah virus in Malaysia, Bangladesh and India, the routes of transmission, prevention and control measures employed along with possible reasons behind the outbreaks, and the precautionary measures to be ensured by private-public undertakings to contain and ensure a lower incidence in the future.

Kaposi's Sarcoma-Associated Herpesvirus Infection Induces the Expression of Neuroendocrine Genes in Endothelial Cells.

Kaposi's sarcoma-associated herpesvirus (KSHV) is etiologically associated with endothelial Kaposi's sarcoma (KS) in immunocompromised individuals. KS lesion cells exhibit many similarities to neuroendocrine (NE) cancers, such as highly vascular and red/purple tumor lesions, spindle-shaped cells, an insignificant role for classic oncogenes in tumor development, the release of bioactive amines, and indolent growth of the tumors. However, the mechanistic basis for the similarity of KS lesion endothelial cells to neuroendocrine tumors remains unknown. Next-generation sequencing and bioinformatics analysis in the present study demonstrate that endothelial cells latently infected with KSHV express several neuronal and NE genes. De novo infection of primary dermal endothelial cells with live and UV-inactivated KSHV demonstrated that viral gene expression is responsible for the upregulation of five selected NE genes (adrenomedullin 2 [ADM2], histamine receptor H1 [HRH1], neuron-specific enolase [NSE] [ENO2], neuronal protein gene product 9.5 [PGP9.5], and somatostatin receptor 1 [SSTR1]). Immunofluorescence and immunohistochemistry examinations demonstrated the robust expression of the NE genes HRH1 and NSE/ENO2 in KSHV-infected KS tissue samples and KS visceral tissue microarrays. Further analysis demonstrated that KSHV latent open reading frame K12 (ORFK12) gene (kaposin A)-mediated decreased host REST/NRSF (RE1-silencing transcription factor/neuron-restrictive silencer factor) protein, a neuronal gene transcription repressor protein, is responsible for NE gene expression in infected endothelial cells. The NE gene expression observed in KSHV-infected cells was recapitulated in uninfected endothelial cells by the exogenous expression of ORFK12 and by the treatment of cells with the REST inhibitor X5050. When the neuroactive ligand-activating receptor HRH1 and inhibitory SSTR1 were knocked out by CRISPR, HRH1 knockout (KO) significantly inhibited cell proliferation, while SSTR1 KO induced cell proliferation, thus suggesting that HRH1 and SSTR1 probably counteract each other in regulating KSHV-infected endothelial cell proliferation. These results demonstrate that the similarity of KS lesion cells to neuroendocrine tumors is probably a result of KSHV infection-induced transformation of nonneuronal endothelial cells into cells with neuroendocrine features. These studies suggest a potential role of neuroendocrine pathway genes in the pathobiological characteristics of KSHV-infected endothelial cells, including a potential mechanism of escape from the host immune system by the expression of immunologically privileged neuronal-site NE genes, and NE genes could potentially serve as markers for KSHV-infected KS lesion endothelial cells as well as novel therapeutic targets to control KS lesions.IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) manipulates several cellular pathways for its survival advantage during its latency in the infected human host. Here, we demonstrate that KSHV infection upregulates the expression of genes related to neuronal and neuroendocrine (NE) functions that are characteristic of NE tumors, both in vitro and in KS patient tissues and the heterogeneity of neuroendocrine receptors having opposing roles in KSHV-infected cell proliferation. Induction of NE genes by KSHV could also provide a potential survival advantage, as the expression of proteins at immunologically privileged sites such as neurons on endothelial cells may be an avenue to escape host immune surveillance functions. The NE gene products identified here could serve as markers for KSHV-infected cells and could potentially serve as therapeutic targets to combat KSHV-associated KS.