The anti-apoptotic function of HSV-1 LAT in neuronal cell cultures but not its function during reactivation correlates with expression of two small non-coding RNAs, sncRNA1&2.

Multiple functions are associated with HSV-1 latency associated transcript (LAT), including establishment of latency, virus reactivation, and antiapoptotic activity. LAT encodes two sncRNAs that are not miRNAs and previously it was shown that they have antiapoptotic activity in vitro. To determine if we can separate the antiapoptotic function of LAT from its latency-reactivation function, we deleted sncRNA1 and sncRNA2 sequences in HSV-1 strain McKrae, creating ΔsncRNA1&2 recombinant virus. Deletion of the sncRNA1&2 in ΔsncRNA1&2 virus was confirmed by complete sequencing of ΔsncRNA1&2 virus and its parental virus. Replication of ΔsncRNA1&2 virus in tissue culture or in the eyes of WT infected mice was similar to that of HSV-1 strain McKrae (LAT-plus) and dLAT2903 (LAT-minus) viruses. The levels of gB DNA in trigeminal ganglia (TG) of mice latently infected with ΔsncRNA1&2 virus was intermediate to that of dLAT2903 and McKrae infected mice, while levels of LAT in TG of latently infected ΔsncRNA1&2 mice was significantly higher than in McKrae infected mice. Similarly, the levels of LAT expression in Neuro-2A cells infected with ΔsncRNA1&2 virus was significantly higher than in McKrae infected cells. Reactivation in TG of ΔsncRNA1&2 infected mice was similar to that of McKrae and time of reactivation in both groups were significantly faster than dLAT2903 infected mice. However, levels of apoptosis in Neuro-2A cells infected with ΔsncRNA1&2 virus was similar to that of dLAT2903 and significantly higher than that of McKrae infected cells. Our results suggest that the antiapoptotic function of LAT resides within the two sncRNAs, which works independently of its latency-reactivation function and it has suppressive effect on LAT expression in vivo and in vitro.

Monocyte to macrophage differentiation and changes in cellular redox homeostasis promote cell type-specific HIV latency reactivation.

HIV latency regulation in monocytes and macrophages can vary according to signals directing differentiation, polarization, and function. To investigate these processes, we generated an HIV latency model in THP-1 monocytes and showed differential levels of HIV reactivation among clonal populations. Monocyte-to-macrophage differentiation of HIV-infected primary human CD14+ and THP-1 cells induced HIV reactivation and showed that virus production increased concomitant with macrophage differentiation. We applied the HIV-infected THP-1 monocyte-to-macrophage (MLat) model to assess the biological mechanisms regulating HIV latency dynamics during monocyte-to-macrophage differentiation. We pinpointed protein kinase C signaling pathway activation and Cyclin T1 upregulation as inherent differentiation mechanisms that regulate HIV latency reactivation. Macrophage polarization regulated latency, revealing proinflammatory M1 macrophages suppressed HIV reactivation while anti-inflammatory M2 macrophages promoted HIV reactivation. Because macrophages rely on reactive-oxygen species (ROS) to exert numerous cellular functions, we disrupted redox pathways and found that inhibitors of the thioredoxin (Trx) system acted as latency-promoting agents in T-cells and monocytes, but opposingly acted as latency-reversing agents in macrophages. We explored this mechanism with Auranofin, a clinical candidate for reducing HIV reservoirs, and demonstrated Trx reductase inhibition led to ROS induced NF-κB activity, which promoted HIV reactivation in macrophages, but not in T-cells and monocytes. Collectively, cell type-specific differences in HIV latency regulation could pose a barrier to HIV eradication strategies.

Reactivation of Epstein-Barr virus among intensive care patients: a prospective observational study.

PURPOSE: Herpesvirus reactivation has been documented among patients in the intensive care unit (ICU) and is associated with increased morbidity and mortality, particularly for cytomegalovirus (CMV). Epstein-Barr virus (EBV) has been poorly studied despite >95% of the population being seropositive. Our preliminary study suggested an association between EBV reactivation and increased morbidity and mortality. This study aimed to investigate this association among patients admitted to the ICU. METHODS: In this multicenter prospective study, polymerase chain reaction was performed to quantify EBV in patients upon ICU admission and then twice a week during their stay. Follow-up was 90 days. RESULTS: The study included 129 patients; 70 (54.3%) had EBV reactivation. On day 90, there was no difference in mortality rates between patients with and without reactivation (25.7% vs 15.3%, p = 0.22). Patients with EBV reactivation at admission had increased mortality compared with those without reactivation and those with later reactivation. EBV reactivation was associated with increased morbidity. Patients with EBV reactivation had fewer ventilator-free days at day 28 than those without reactivation (18 [1-22] vs. 21 days [5-26], p = 0.037) and a higher incidence of acute respiratory distress syndrome (34.3% vs. 17%, p = 0.04), infections (92.9% vs. 78%, p = 0.03), and septic shock (58.6% vs. 32.2%, p = 0.004). More patients with EBV reactivation required renal replacement therapy (30% vs. 11.9%, p = 0.02). EBV reactivation was also associated with a more inflammatory immune profile. CONCLUSION: While EBV reactivation was not associated with increased 90-day mortality, it was associated with significantly increased morbidity.

Awakening the sleeping giant: Epstein-Barr virus reactivation by biological agents.

Epstein-Barr virus (EBV) may cause harm in immunocompromised conditions or on stress stimuli. Various chemical agents have been utilized to induce the lytic cycle in EBV-infected cells. However, apart from chemical agents and external stress stimuli, certain infectious agents may reactivate the EBV. In addition, the acute infection of other pathogens may provide suitable conditions for EBV to thrive more and planting the roots for EBV-associated pathologies. Various bacteria such as periodontal pathogens like Aggregatibacter, Helicobacter pylori, etc. have shown to induce EBV reactivation either by triggering host cells directly or indirectly. Viruses such as Human simplex virus-1 (HSV) induce EBV reactivation by HSV US3 kinase while other viruses such as HIV, hepatitis virus, and even novel SARS-CoV-2 have also been reported to cause EBV reactivation. The eukaryotic pathogens such as Plasmodium falciparum and Aspergillus flavus can also reactivate EBV either by surface protein interaction or as an impact of aflatoxin, respectively. To highlight the underexplored niche of EBV reactivation by biological agents, we have comprehensively presented the related information in this review. This may help to shedding the light on the research gaps as well as to unveil yet unexplored mechanisms of EBV reactivation.

[Guillain-Barré syndrome associated with Epstein-Barr virus and cytomegalovirus reactivation during treatment for chronic graft-versus-host disease after allogeneic bone marrow transplantation].

Guillain-Barré syndrome (GBS) is a rare neurological complication of allogeneic hematopoietic stem cell transplantation (HSCT). The pathogenesis of post-HSCT GBS is unclear. Here, we report a case of GBS coincident with Epstein-Barr virus (EBV) and cytomegalovirus (CMV) reactivation that occurred after HSCT in a patient with myelodysplastic syndrome. A 61-year-old man was admitted to our hospital because of gait disturbance due to lower limb muscle weakness, which arose during treatment for chronic graft-versus-host disease (GVHD) five months after allogeneic HSCT. He was diagnosed with GBS based on his clinical course, cerebrospinal fluid analysis, and a nerve conduction study. At that time, he exhibited EBV and CMV reactivation. GBS improved after intravenous injection of immunoglobulins. Our case suggests that reactivation of EBV and CMV during treatment for chronic GVHD may induce GBS, and that rapidly progressive muscular weakness coincident with EBV or CMV reactivation can be a diagnostic sign of GBS after allogeneic HSCT.

SIRT-1 is required for release of enveloped enteroviruses.

Enterovirus D68 (EV-D68) is a re-emerging enterovirus that causes acute respiratory illness in infants and has recently been linked to Acute Flaccid Myelitis. Here, we show that the histone deacetylase, SIRT-1, is essential for autophagy and EV-D68 infection. Knockdown of SIRT-1 inhibits autophagy and reduces EV-D68 extracellular titers. The proviral activity of SIRT-1 does not require its deacetylase activity or functional autophagy. SIRT-1's proviral activity is, we demonstrate, mediated through the repression of endoplasmic reticulum stress (ER stress). Inducing ER stress through thapsigargin treatment or SERCA2A knockdown in SIRT-1 knockdown cells had no additional effect on EV-D68 extracellular titers. Knockdown of SIRT-1 also decreases poliovirus and SARS-CoV-2 titers but not coxsackievirus B3. In non-lytic conditions, EV-D68 is primarily released in an enveloped form, and SIRT-1 is required for this process. Our data show that SIRT-1, through its translocation to the cytosol, is critical to promote the release of enveloped EV-D68 viral particles.

The Intersection of Innate Immune Pathways with the Latent Herpes Simplex Virus Genome.

Innate immune responses can impact different stages of viral life cycles. Herpes simplex virus latent infection of neurons and subsequent reactivation provide a unique context for immune responses to intersect with different stages of infection. Here, we discuss recent findings linking neuronal innate immune pathways with the modulation of latent infection, acting at the time of reactivation and during initial neuronal infection to have a long-term impact on the ability of the virus to reactivate.

Competition between lysogenic and sensitive bacteria is determined by the fitness costs of the different emerging phage-resistance strategies.

Many bacterial genomes carry prophages whose induction can eliminate competitors. In response, bacteria may become resistant by modifying surface receptors, by lysogenization, or by other poorly known processes. All these mechanisms affect bacterial fitness and population dynamics. To understand the evolution of phage resistance, we co-cultivated a phage-sensitive strain (BJ1) and a polylysogenic Klebsiella pneumoniae strain (ST14) under different phage pressures. The population yield remained stable after 30 days. Surprisingly, the initially sensitive strain remained in all populations and its frequency was highest when phage pressure was strongest. Resistance to phages in these populations emerged initially through mutations preventing capsule biosynthesis. Protection through lysogeny was rarely observed because the lysogens have increased death rates due to prophage induction. Unexpectedly, the adaptation process changed at longer time scales: the frequency of capsulated cells in BJ1 populations increased again because the production of the capsule was fine-tuned, reducing the ability of phage to absorb. Contrary to the lysogens, these capsulated-resistant clones are pan-resistant to a large panel of phages. Intriguingly, some clones exhibited transient non-genetic resistance to phages, suggesting an important role of phenotypic resistance in coevolving populations. Our results show that interactions between lysogens and sensitive strains are shaped by antagonistic co-evolution between phages and bacteria. These processes may involve key physiological traits, such as the capsule, and depend on the time frame of the evolutionary process. At short time scales, simple and costly inactivating mutations are adaptive, but in the long term, changes drawing more favorable trade-offs between resistance to phages and cell fitness become prevalent.

EBV Reactivation from Latency Is a Degrading Experience for the Host.

During reactivation from latency, gammaherpesviruses radically restructure their host cell to produce virion particles. To achieve this and thwart cellular defenses, they induce rapid degradation of cytoplasmic mRNAs, suppressing host gene expression. In this article, we review mechanisms of shutoff by Epstein-Barr virus (EBV) and other gammaherpesviruses. In EBV, canonical host shutoff is accomplished through the action of the versatile BGLF5 nuclease expressed during lytic reactivation. We explore how BGLF5 induces mRNA degradation, the mechanisms by which specificity is achieved, and the consequences for host gene expression. We also consider non-canonical mechanisms of EBV-induced host shutoff. Finally, we summarize the limitations and barriers to accurate measurements of the EBV host shutoff phenomenon.

Signals triggering prophage induction in the gut microbiota.

Compared to bacteria of the gut microbiota, bacteriophages are still poorly characterised, and their physiological importance is far less known. Temperate phages are probably a major actor in the gut, as it is estimated that 80% of intestinal bacteria are lysogens, meaning that they are carrying prophages. In addition, prophage induction rates are higher in the gut than in vitro. However, studies on the signals leading to prophage induction have essentially focused on genotoxic agents with poor relevance for this environment. In this review, we sum up recent findings about signals able to trigger prophage induction in the gut. Three categories of signals are at play: those originating from interactions between intestinal microbes, those from the human or animal host physiology and those from external intakes. These recent results highlight the diversity of factors influencing prophage induction in the gut, and start to unveil ways by which microbiota composition may be modulated.

[Reactivation of latent viruses in Neurology].

After establishing latent infection, some viruses can be reactivated by the alteration of host immunological conditions. First, we reviewed viruses that can cause neuronal damage by reactivation. Then we focused on the herpes simplex virus (HSV). The reactivation leads to neuronal damages through two possible mechanisms; "reactivation of a latent herpes virus" by which viruses can cause direct virus neurotoxicity, and "post-infectious immune inflammatory response" by which a focal reactivation of HSV leads to an inflammatory reaction. The former is radiologically characterized by cortical lesions, the latter is characterized by subcortical white matter lesions. We experienced a female, who underwent the right posterior quadrantectomy and then developed recurrent herpes encephalitis caused by herpes simplex reactivation, which pathologically demonstrated inflammation in the white matter, suggesting a post-infectious immune inflammatory response. The patient was successfully treated with immunosuppressants. The reactivation of the HSV is extremely rare in Japan. Neurologists should recognize this condition because this disorder will increase as epilepsy surgery gains more popularity.

A Single Herpes Simplex Virus 1 Genome Reactivates from Individual Cells.

Latent infection is a characteristic feature of herpesviruses' life cycle. Herpes simplex virus 1 is a common human pathogen that establishes lifelong latency in peripheral neurons. Symptomatic or asymptomatic periodic reactivations from the latent state allow the virus to replicate and spread among individuals. The latent viral genomes are found as several quiescent episomes inside the infected nuclei; however, it is not clear if and how many latent genomes are able to reactivate together. To address this question, we developed a quiescent infection assay, which provides a quantitative analysis of the number of genomes reactivating per cell, in cultured immortalized fibroblasts. We found that, almost always, only one viral genome reactivates per cell. We showed that different timing of entry to quiescence did not result in a significant change in the probability of reactivating. Reactivation from this quiescent state allowed only limited intergenomic recombination between two viral strains compared to lytic infection. Following coinfection with a mutant that is unable to reactivate, only coreactivation with a reactivation-proficient recombinant can provide the opportunity for the mutant to reactivate. We speculate that each individual quiescent viral genome has a low and stochastic chance to reactivate in each cell, an assumption that can explain the limited number of genomes reactivating per cell. IMPORTANCE Herpesviruses are highly prevalent and cause significant morbidity in the human and animal populations. Most individuals who are infected with herpes simplex virus (HSV-1), a common human pathogen, will become lifelong carriers of the virus, as HSV-1 establishes latent (quiescent) infections in the host cells. Reactivation from the latent state leads to many of the viral symptoms and to the spread of the virus among individuals. While many triggers for reactivation were identified, how many genomes reactivate from an individual cell and how are these genomes selected remain understudied. Here, we identify that, in most cases, only one genome per cell reactivates. Mutated HSV-1 genomes require coinfection with another strain to allow coreactivation. Our findings suggest that the decision to reactivate is determined for each quiescent genome separately and support the notion that reactivation preferences occur at the single-genome level.

Features of Epstein-Barr Virus and Cytomegalovirus Reactivation in Acute Leukemia Patients After Haplo-HCT With Myeloablative ATG-Containing Conditioning Regimen.

Background: Haploidentical donor hematopoietic cell transplantation (haplo-HCT) has become a preferred option for patients without HLA-matched donors, but it increases the risk of viral reactivations. Epstein-Barr virus (EBV) and cytomegalovirus (CMV) are common viruses post-HCT, but limited data have been reported in the setting of haplo-HCT. Methods: We conducted a retrospective study enrolling acute leukemia patients who received haplo-HCT with myeloablative conditioning regimen employing ATG in our center from July 2014 to July 2017. All the patients enrolled were EBV-IgM and EBV-DNA negative but EBV-IgG positive, and so were their donors. The same went for CMV as well. Results: In total, 602 patients were recruited consisting of 331 with acute myeloid leukemia (AML) and 271 with acute lymphoblastic leukemia (ALL). One-year cumulative incidences of EBV (22.9% ± 2.4% vs. 27.4% ± 2.8%, P = 0.169) and CMV (24.7% ± 2.4% vs. 29.4% ± 2.8%, P = 0.190) reactivation were comparable between AML and ALL. EBV and CMV were independent risk factors for each other. In the AML group, male recipients [HR = 1.275, 95% CI (1.001-1.624), P = 0.049] and acute graft-versus-host disease [HR = 1.592, 95% CI (1.001-2.533), P = 0.049] were independent risk factors for EBV reactivation and CMV reactivation, respectively. CMV rather than EBV reactivation was related to a trend of worsened treatment-related mortality (TRM) (15.6% ± 0.1% vs. 10.2% ± 0.0%, P = 0.067) and progression-free survival (PFS) (60.6% ± 4.1% vs. 70.3% ± 2.3%, P = 0.073), while significant impacts were revealed only in the subgroup analysis. CMV reactivation resulted in a remarkable inferior 2-year overall survival (OS) (64.2% ± 5.7% vs. 77.6% ± 3.2%, P = 0.038) and PFS (55.0% ± 5.9% vs. 71.9% ± 3.4%, P = 0.042) in ALL patients. On the other hand, in the EBV+/CMV- subgroup, relapse was lower in ALL patients (8.2% ± 0.2% vs. 32.4% ± 0.8%, P = 0.010) compared with AML patients, which led to a superior 2-year OS (82.0% ± 6.2% vs. 60.3% ± 8.8%, P = 0.016) and PFS (74.5% ± 7.0% vs. 57.5% ± 8.4%, P = 0.036). Conclusion: We concluded that EBV and CMV reactivations were frequent in acute leukemia patients after haplo-HCT, with possibly distinctive risk factors from HLA-matched HCT. There could be a potential interaction between EBV and CMV, but impacts on transplant outcomes remained complex.

Impact of Cultured Neuron Models on α-Herpesvirus Latency Research.

A signature trait of neurotropic α-herpesviruses (α-HV) is their ability to establish stable non-productive infections of peripheral neurons termed latency. This specialized gene expression program is the foundation of an evolutionarily successful strategy to ensure lifelong persistence in the host. Various physiological stresses can induce reactivation in a subset of latently-infected neurons allowing a new cycle of viral productive cycle gene expression and synthesis of infectious virus. Recurring reactivation events ensure transmission of the virus to new hosts and contributes to pathogenesis. Efforts to define the molecular basis of α-HV latency and reactivation have been notoriously difficult because the neurons harboring latent virus in humans and in experimentally infected live-animal models, are rare and largely inaccessible to study. Increasingly, researchers are turning to cultured neuron infection models as simpler experimental platforms from which to explore latency and reactivation at the molecular level. In this review, I reflect on the strengths and weaknesses of existing neuronal models and briefly summarize the important mechanistic insights these models have provided. I also discuss areas where prioritization will help to ensure continued progress and integration.

Ex Vivo Herpes Simplex Virus Reactivation Involves a Dual Leucine Zipper Kinase-Dependent Wave of Lytic Gene Expression That Is Independent of Histone Demethylase Activity and Viral Genome Synthesis.

Herpes simplex virus 1 (HSV-1) maintains a lifelong latent infection in neurons and periodically reactivates, resulting in the production of infectious virus. The exact cellular pathways that induce reactivation are not understood. In primary neuronal models of HSV latency, the cellular protein dual leucine zipper kinase (DLK) has been found to initiate a wave of viral gene expression known as phase I. Phase I occurs independently of both viral DNA replication and the activities of histone demethylase enzymes required to remove repressive heterochromatin modifications associated with the viral genome. In this study, we investigated whether phase I-like gene expression occurs in ganglia reactivated from infected mice. Using the combined trigger of explant-induced axotomy and inhibition of phosphatidylinositide 3-kinase (PI3K) signaling, we found that HSV lytic gene expression was induced rapidly from both sensory and sympathetic neurons. Ex vivo reactivation involved a wave of viral late gene expression that occurred independently of viral genome synthesis and histone demethylase activity and preceded the detection of infectious virus. Importantly, we found that DLK was required for the initial induction of lytic gene expression. These data confirm the essential role of DLK in inducing HSV-1 gene expression from the heterochromatin-associated genome and further demonstrate that HSV-1 gene expression during reactivation occurs via mechanisms that are distinct from lytic replication. IMPORTANCE Reactivation of herpes simplex virus from a latent infection is associated with clinical disease. To develop new therapeutics that prevent reactivation, it is important to understand how viral gene expression initiates following a reactivation stimulus. Dual leucine zipper kinase (DLK) is a cellular protein that has previously been found to be required for HSV reactivation from sympathetic neurons in vitro. Here, we show that DLK is essential for reactivation from sensory ganglia isolated from infected mice. Furthermore, we show that DLK-dependent gene expression ex vivo occurs via mechanisms that are distinct from production replication, namely, lytic gene expression that is independent of viral DNA replication and histone demethylase activity. The identification of a DLK-dependent wave of lytic gene expression from sensory ganglia will ultimately permit the development of novel therapeutics that target lytic gene expression and prevent the earliest stage of reactivation.

Management of hepatitis B virus reactivation due to treatment of COVID-19.

The world has made significant progress in developing novel treatments for COVID-19 since the pandemic began. Some treatments target the patient's dysregulated inflammatory response during COVID-19 infection and may cause hepatitis B reactivation (HBVr) in patients with current or past hepatitis B virus (HBV) infection. This review summarizes the risk and management of HBVr due to different treatments of COVID-19 in patients who have current or past HBV infection. Abnormal liver function tests are common during COVID-19 infection. Current evidence suggests that current or past HBV infection is not associated with an increased risk of liver injury and severe disease in COVID-19 patients. Among patients who received high-dose corticosteroids, various immunosuppressive monoclonal antibodies and inhibitors of Janus kinase, the risk of HBVr exists, especially among those without antiviral prophylaxis. Data, however, remain scarce regarding the specific use of immunosuppressive therapies in COVID-19 patients with HBV infection. Some results are mainly extrapolated from patients receiving the same agents in other diseases. HBVr is a potentially life-threatening event following profound immunosuppression by COVID-19 therapies. Future studies should explore the use of immunosuppressive therapies in COVID-19 patients with HBV infection and the impact of antiviral prophylaxis on the risk of HBVr.

Absence of signal peptide peptidase in peripheral sensory neurons affects latency-reactivation in HSV-1 ocularly infected mice.

We previously reported that HSV-1 infectivity in vitro and in vivo requires HSV glycoprotein K (gK) binding to the ER signal peptide peptidase (SPP). Anterograde-retrograde transport via peripheral nerves between the site of infection (i.e., eye) and the site of latency (neurons) is a critical process to establish latency and subsequent viral reactivation. Given the essential role of neurons in HSV-1 latency-reactivation, we generated mice lacking SPP specifically in peripheral sensory neurons by crossing Advillin-Cre mice with SPPfl/fl mice. Expression of SPP mRNA and protein were significantly lower in neurons of Avil-SPP-/- mice than in control mice despite similar levels of HSV-1 replication in the eyes of Avil-SPP-/- mice and control mice. Viral transcript levels in isolated neurons of infected mice on days 2 and 5 post infection were lower than in control mice. Significantly less LAT, gB, and PD-1 expression was seen during latency in isolated neurons and total trigeminal ganglia (TG) of Avil-SPP-/- mice than in control mice. Finally, reduced latency and reduced T cell exhaustion in infected Avil-SPP-/- mice correlated with slower and no reactivation. Overall, our results suggest that blocking SPP expression in peripheral sensory neurons does not affect primary virus replication or eye disease but does reduce latency-reactivation. Thus, blocking of gK binding to SPP may be a useful tool to reduce latency-reactivation.

Reactivation of EBV and CMV in Severe COVID-19-Epiphenomena or Trigger of Hyperinflammation in Need of Treatment? A Large Case Series of Critically ill Patients.

BACKGROUND: Reactivation of viruses such as Epstein-Barr virus (EBV) and cytomegalovirus (CMV) are common in critically ill patients and have been described in patients with severe COVID-19. However, it is unclear whether these reactivations are associated with increased mortality and whether targeted treatments are beneficial. METHODS: In a retrospective single-center cohort study, patients with severe COVID-19 treated on our intensive care unit (ICU) were screened for EBV and CMV reactivation as detected by polymerase chain reaction. If present, patient characteristics, temporal connections to severe acute respiratory syndrome coronavirus 2 diagnosis and corticosteroid use, the use of targeted treatments as well as the course of disease and outcome were analyzed. As control group, non-COVID-19 patients with sepsis, treated within the same time period on our ICU, served as control group to compare incidences of viral reactivation. RESULTS: In 19 (16%) of 117 patients with severe COVID-19 treated on our ICU EBV reactivations were identified, comparable 18 (14%) of 126 in the non-COVID-19 control group (P = .672). Similarly, in 11 (9%) of 117 patients CMV reactivations were identified, comparable to the 16 (13%) of 126 in the non-COVID-19 sepsis patients (P = .296). The majority of EBV (58%) and CMV reactivations (55%) were detected in patients under systemic corticosteroid treatment. 7 (37%) of 19 patients with EBV reactivation survived the ICU stay, 2 (29%) of 7 patients with rituximab treatment and 5 (42%) of 12 patients without treatment (P = .568). Five (50%) of 10 patients with CMV reactivation survived the ICU stay, 5 (83%) of 6 patients with ganciclovir treatment and 0 of 4 patients without treatment (P = .048). Follow-up analysis in these patients showed that the initiation of treatment lead to decrease in viral load. CONCLUSION: Critically ill patients with COVID-19 are at a high risk for EBV and CMV reactivations. Whether these reactivations are a cause of hyperinflammation and require targeted treatment remains uncertain. However, in patients with clinical deterioration or signs of hyperinflammation targeted treatment might be beneficial and warrants further studying.

Analysis of Morphological Changes in the CNS and Internal Organs of Macaca mulatta Monkeys after Intracerebral Injection of a Low-Attenuated Rubella Virus Strain.

We studied the localization and severity of morphological changes in CNS and internal organs of animals intacerebrally infected with a low-attenuated rubella virus strain "Orlov-14". The data obtained can be used as morphological criteria reflecting low level of attenuation of rubella virus strains to improve the control of the safety of attenuated strains of live rubella vaccines.

Biogenesis of P-TEFb in CD4+ T cells to reverse HIV latency is mediated by protein kinase C (PKC)-independent signaling pathways.

The switch between HIV latency and productive transcription is regulated by an auto-feedback mechanism initiated by the viral trans-activator Tat, which functions to recruit the host transcription elongation factor P-TEFb to proviral HIV. A heterodimeric complex of CDK9 and one of three cyclin T subunits, P-TEFb is expressed at vanishingly low levels in resting memory CD4+ T cells and cellular mechanisms controlling its availability are central to regulation of the emergence of HIV from latency. Using a well-characterized primary T-cell model of HIV latency alongside healthy donor memory CD4+ T cells, we characterized specific T-cell receptor (TCR) signaling pathways that regulate the generation of transcriptionally active P-TEFb, defined as the coordinate expression of cyclin T1 and phospho-Ser175 CDK9. Protein kinase C (PKC) agonists, such as ingenol and prostratin, stimulated active P-TEFb expression and reactivated latent HIV with minimal cytotoxicity, even in the absence of intracellular calcium mobilization with an ionophore. Unexpectedly, inhibition-based experiments demonstrated that PKC agonists and TCR-mobilized diacylglycerol signal through MAP kinases ERK1/2 rather than through PKC to effect the reactivation of both P-TEFb and latent HIV. Single-cell and bulk RNA-seq analyses revealed that of the four known isoforms of the Ras guanine nucleotide exchange factor RasGRP, RasGRP1 is by far the predominantly expressed diacylglycerol-dependent isoform in CD4+ T cells. RasGRP1 should therefore mediate the activation of ERK1/2 via Ras-Raf signaling upon TCR co-stimulation or PKC agonist challenge. Combined inhibition of the PI3K-mTORC2-AKT-mTORC1 pathway and the ERK1/2 activator MEK prior to TCR co-stimulation abrogated active P-TEFb expression and substantially suppressed latent HIV reactivation. Therefore, contrary to prevailing models, the coordinate reactivation of P-TEFb and latent HIV in primary T cells following either TCR co-stimulation or PKC agonist challenge is independent of PKC but rather involves two complementary signaling arms of the TCR cascade, namely, RasGRP1-Ras-Raf-MEK-ERK1/2 and PI3K-mTORC2-AKT-mTORC1.