Nuclear Capsid Research Articles

The Autophagy Receptor SQSTM1/p62 Is a Restriction Factor of HCMV Infection.

(1) Background: Intrinsic defense mechanisms are pivotal host strategies to restrict viruses already at early stages of their infection. Here, we addressed the question of how the autophagy receptor sequestome 1 (SQSTM1/p62, hereafter referred to as p62) interferes with human cytomegalovirus (HCMV) infection. (2) Methods: CRISPR/Cas9-mediated genome editing, mass spectrometry and the expression of p62 phosphovariants from recombinant HCMVs were used to address the role of p62 during infection. (3) Results: The knockout of p62 resulted in an increased release of HCMV progeny. Mass spectrometry revealed an interaction of p62 with cellular proteins required for nucleocytoplasmic transport. Phosphoproteomics further revealed that p62 is hyperphosphorylated at position S272 in HCMV-infected cells. Phosphorylated p62 showed enhanced nuclear retention, which is concordant with enhanced interaction with viral proteins relevant for genome replication and nuclear capsid egress. This modification led to reduced HCMV progeny release compared to a non-phosphorylated version of p62. (4) Conclusions: p62 is a restriction factor for HCMV replication. The activity of the receptor appears to be regulated by phosphorylation at position S272, leading to enhanced nuclear localization, viral protein degradation and impaired progeny production.

The precise function of alphaherpesvirus tegument proteins and their interactions during the viral life cycle.

Alphaherpesvirus is a widespread pathogen that causes diverse diseases in humans and animals and can severely damage host health. Alphaherpesvirus particles comprise a DNA core, capsid, tegument and envelope; the tegument is located between the nuclear capsid and envelope. According to biochemical and proteomic analyses of alphaherpesvirus particles, the tegument contains at least 24 viral proteins and plays an important role in the alphaherpesvirus life cycle. This article reviews the important role of tegument proteins and their interactions during the viral life cycle to provide a reference and inspiration for understanding alphaherpesvirus infection pathogenesis and identifying new antiviral strategies.

Genetics of immune response to Epstein-Barr virus: prospects for multiple sclerosis pathogenesis.

Epstein-Barr virus (EBV) infection has been advocated as a prerequisite for developing multiple sclerosis (MS) and possibly the propagation of the disease. However, the precise mechanisms for such influences are still unclear. A large-scale study investigating the host genetics of EBV serology and related clinical manifestations, such as infectious mononucleosis (IM), may help us better understand the role of EBV in MS pathogenesis. This study evaluates the host genetic factors that influence serological response against EBV and history of IM and cross-evaluates them with MS risk and genetic susceptibility in the Swedish population. Plasma IgG antibody levels against EBV nuclear antigen-1 [EBNA-1, truncated = amino acids (aa) (325-641), peptide = aa(385-420)] and viral capsid antigen p18 (VCAp18) were measured using bead-based multiplex serology for 8744 MS cases and 7229 population-matched control subjects. The MS risk association for high/low EBV antibody levels and history of IM was compared to relevant clinical measures along with sex, age at sampling, and associated HLA allele variants. Genome-wide and HLA allele association analyses were also performed to identify genetic risk factors for EBV antibody response and IM history. Higher antibody levels against VCAp18 [odds ratio (OR) = 1.74, 95% confidence interval (CI) = 1.60-1.88] and EBNA-1, particularly the peptide (OR = 3.13, 95% CI = 2.93-3.35), were associated with an increased risk for MS. The risk increased with higher anti-EBNA-1 IgG levels up to 12× the reference risk. We also identified several independent HLA haplotypes associated with EBV serology overlapping with known MS risk alleles (e.g. DRB1*15:01). Although there were several candidates, no variants outside the HLA region reached genome-wide significance. Cumulative HLA risk for anti-EBNA-1 IgG levels, particularly the peptide fragment, was strongly associated with MS. In contrast, the genetic risk for high anti-VCAp18 IgG levels was not as strongly associated with MS risk. IM history was not associated with class II HLA genes but negatively associated with A*02:01, which is protective against MS. Our findings emphasize that the risk association between anti-EBNA-1 IgG levels and MS may be partly due to overlapping HLA associations. Additionally, the increasing MS risk with increasing anti-EBNA-1 levels would be consistent with a pathogenic role of the EBNA-1 immune response, perhaps through molecular mimicry. Given that high anti-EBNA-1 antibodies may reflect a poorly controlled T-cell defence against the virus, our findings would be consistent with DRB1*15:01 being a poor class II antigen in the immune defence against EBV. Last, the difference in genetic control of IM supports the independent roles of EBNA-1 and IM in MS susceptibility.

'Getting Better'-Is It a Feasible Strategy of Broad Pan-Antiherpesviral Drug Targeting by Using the Nuclear Egress-Directed Mechanism?

The herpesviral nuclear egress represents an essential step of viral replication efficiency in host cells, as it defines the nucleocytoplasmic release of viral capsids. Due to the size limitation of the nuclear pores, viral nuclear capsids are unable to traverse the nuclear envelope without a destabilization of this natural host-specific barrier. To this end, herpesviruses evolved the regulatory nuclear egress complex (NEC), composed of a heterodimer unit of two conserved viral NEC proteins (core NEC) and a large-size extension of this complex including various viral and cellular NEC-associated proteins (multicomponent NEC). Notably, the NEC harbors the pronounced ability to oligomerize (core NEC hexamers and lattices), to multimerize into higher-order complexes, and, ultimately, to closely interact with the migrating nuclear capsids. Moreover, most, if not all, of these NEC proteins comprise regulatory modifications by phosphorylation, so that the responsible kinases, and additional enzymatic activities, are part of the multicomponent NEC. This sophisticated basis of NEC-specific structural and functional interactions offers a variety of different modes of antiviral interference by pharmacological or nonconventional inhibitors. Since the multifaceted combination of NEC activities represents a highly conserved key regulatory stage of herpesviral replication, it may provide a unique opportunity towards a broad, pan-antiherpesviral mechanism of drug targeting. This review presents an update on chances, challenges, and current achievements in the development of NEC-directed antiherpesviral strategies.

DOP20 Changes in systemic antibody epitope repertoires from preclinical to established Inflammatory Bowel Disease

Abstract Background Inflammatory bowel diseases (IBD), encompassing Crohn's disease (CD) and ulcerative colitis (UC), exhibit unique immunological changes early in development. Although >300 IBD-specific antibody responses have been identified1, systemic antibody epitope repertoires of preclinical IBD remain elusive. This study aimed to profile systemic antibody responses at unprecedented depth in individuals before and after the onset of IBD, aiming to identify preclinical disease biomarkers. Methods This study included individuals participating in the Lifelines Cohort Study, a large prospective population-based cohort study in the Netherlands including 167,000 individuals with longitudinal follow-up. Participants without IBD at baseline were screened for any reported IBD diagnosis during follow-up (2006-2021). Individuals who reported IBD during follow-up and with available serum samples were included. Samples at baseline (pre-diagnosis) and during follow-up (post-diagnosis) were used to profile antibody repertoires against 344,000 rationally selected microbial-, food-, and immune antigens using phage-display immunoprecipitation sequencing (PhIP-Seq). Results A total of 178 individuals with new-onset IBD were identified (Fig. 1). Median follow-up time until diagnosis was 3.9 (IQR: 3.4-4.3) years. Most individuals reported newly developed UC (n=123, 69.1%), followed by CD (n=44, 24.7%), and undetermined IBD (IBD-U, n=11, 6.2%). A total of 5,174 antibody responses were observed in 5-95% of participants. Fifty-nine antibodies were differentially abundant (FDR<0.05) pre-diagnosis vs. post-diagnosis (Fig. 2), 14 of which (24%) were previously reported as IBD-specific1. Thirteen were more (22%) and 46 less (78%) frequently observed post-diagnosis. Those developing UC exhibited 33 differentially abundant antibody responses, while those with CD exhibiting only four (FDR<0.05). Individuals developing IBD exhibited lower frequencies of antibody responses against EBV-associated peptides post-diagnosis, e.g. Epstein-Barr nuclear antigen-1 (EBNA-1) and capsid protein V26, and varicella-zoster virus, alongside higher antibody responses against bacterial flagellins. Individuals developing UC showed elevated antibody responses mainly against viruses (e.g. human adenovirus C, enteroviruses B/C) and particular pathogenic bacterial species (e.g. pneumococcal histidine triad proteins) post-diagnosis compared to pre-diagnosis. Conclusion Distinct antibody responses appear years before IBD diagnosis, indicating potential involvement in pre-clinical disease development. Furthermore, post-diagnosis, lower frequencies of antibody responses against EBV may suggest reduced immunogenicity against this virus in early disease pathogenesis. 1. Bourgonje et al. Immunity. 2023.

HIV-1 Capsid Uncoating Is a Multistep Process That Proceeds through Defect Formation Followed by Disassembly of the Capsid Lattice.

The HIV-1 core consists of a cone-shaped capsid shell made of capsid protein (CA) hexamers and pentamers encapsulating the viral genome. HIV-1 capsid disassembly, referred to as uncoating, is important for productive infection; however, the location, timing, and regulation of uncoating remain controversial. Here, we employ amber codon suppression to directly label CA. In addition, a fluid phase fluorescent probe is incorporated into the viral core to detect small defects in the capsid lattice. This double-labeling strategy enables the visualization of uncoating of single cores in vitro and in living cells, which we found to always proceed through at least two distinct steps─the formation of a defect in the capsid lattice that initiates gradual loss of CA below a detectable level. Importantly, intact cores containing the fluid phase and CA fluorescent markers enter and uncoat in the nucleus, as evidenced by a sequential loss of both markers, prior to establishing productive infection. This two-step uncoating process is observed in different cells, including a macrophage line. Notably, the lag between the release of fluid phase marker and terminal loss of CA appears to be independent of the cell type or reverse transcription and is much longer (>5-fold) for nuclear capsids compared to cell-free cores or cores in the cytosol, suggesting that the capsid lattice is stabilized by capsid-binding nuclear factors. Our results imply that intact HIV-1 cores enter the cell nucleus and that uncoating is initiated through a localized defect in the capsid lattice prior to a global loss of CA.

Tg1.4HBV-s-rec mice, a crossbred hepatitis B virus-transgenic model, develop mild hepatitis

Hepatitis B virus (HBV)-transgenic mice exhibit competent innate immunity and are therefore an ideal model for considering intrinsic or cell-based mechanisms in HBV pathophysiology. A highly replicative model that has been little used, let alone characterized, is the Tg1.4HBV-s-rec strain derived from cross breeding of HBV-transgenic mouse models that either accumulate (Alb/HBs, Tg[Alb1-HBV]Bri44) or lack (Tg1.4HBV-s-mut) the hepatitis B surface antigen (HBsAg). Tg1.4HBV-s-rec hepatocytes secreted HBsAg, Hepatitis B extracellular antigen (HBeAg) and produced HBV virions. Transmission electron microscopy visualised viral particles (Tg1.4HBV-s-rec), nuclear capsid formations (Tg1.4HBV-s-mut and Tg1.4HBV-s-rec) and endoplasmic reticulum malformations (Alb/HBs). Viral replication in Tg1.4HBV-s-rec and Tg1.4HBV-s-mut differed in HBsAg expression and interestingly in the distribution of HBV core antigen (HBcAg) and HBV × protein. While in Tg1.4HBV-s-mut hepatocytes, the HBcAg was located in the cytoplasm, in Tg1.4HBV-s-rec hepatocytes, the HBcAg appeared in the nuclei, suggesting a more productive replication. Finally, Tg1.4HBV-s-rec mice showed symptoms of mild hepatitis, with reduced liver function and elevated serum transaminases, which appeared to be related to natural killer T cell activation. In conclusion, the study of Alb/HBs, Tg1.4HBV-s-mut and their F1 progeny provides a powerful tool to elucidate HBV pathophysiology, especially in the early HBeAg-positive phases of chronic infection and chronic hepatitis.

Collagen-Filler Injection Associated Dermopathy and COVID-19

COVID-19 and cosmetic skin-fillers are two prevalent topics of today’s medicine, yet their interaction is not sufficiently studied. This article is based on a clinico-morphological case where the patient, a 37-year-old female, visited the clinic with complaints of painless palpable subcutaneous pathologic nodular lesions at the site of collagen cosmetic filler injection after severe acute respiratory syndrome coronavirus 2 infection. In order to verify the pathological processes of the lesions, punch biopsy of the affected skin was taken, and histological, histochemical, and immunohistochemical studies were conducted. Atrophy, acanthosis, parakeratosis with vacuolisation of nuclei of the epidermis; sclerosis and abnormal deposition of collagen fibres in the subepithelial layer of dermis; and vasculitis with endothelial hypertrophy and lymphoid perivascular infiltration (CD3 lymphocytes and CD68 macrophages) were found. Spike and nuclear capsid proteins of severe acute respiratory syndrome coronavirus 2 were localised in cells of perivascular inflammatory infiltrates, endothelial cells, and epithelium of glands and epidermis of the skin. The association between the dermatopathy in COVID-19 virus infection and cosmetic fillers were established. The authors discuss and hypothesise possible autoimmune processes that lead to autoimmune vasculitis.

A Systematic Review of Epstein-Barr Virus Antibodies as Clinical Biomarkers in Multiple Sclerosis (P1-3.007)

<h3>Objective:</h3> To systematically review Epstein-Barr Virus (EBV) titers as prognostic biomarkers in MS. <h3>Background:</h3> EBV is a necessary but insufficient factor in the pathophysiology of multiple sclerosis (MS). EBV antibodies to the nuclear antigen (EBNA1) and viral capsid antigen (VCA) rise rapidly prior to disease manifestations, and their absence could be used clinically given a high negative predictive value. It is unclear whether EBV titers act as prognostic, monitoring, or pharmacodynamic/response biomarkers. Significant literature on this topic exists but has not been synthesized. We hypothesized that EBV titers against the nuclear (EBNA1) and capsid (VCA) antigens are potential prognostic and monitoring biomarkers in MS, and that the patient population, MS clinical phenotype, and EBV assay method may play important roles in explaining variability among study outcomes. <h3>Design/Methods:</h3> We performed a systemic query in PubMed and EMBASE from inception to April 1, 2022. After removal of duplicates, records were screened by abstract. Remaining full text articles were reviewed. Clinical and MRI data were extracted from full text articles for comparison and synthesis. <h3>Results:</h3> Searches yielded 696 unique results, of which 285 were reviewed in full and 35 met criteria for data extraction. Heterogeneity in sample population, clinical outcome measures, assay methods and statistical analyses precluded a meta-analysis. EBV titers were not consistently associated with clinical disease markers including conversion from CIS to RRMS, neurological disability, or disease phenotype. Data from multiple studies show that titers may temporarily reflect inflammatory disease activity assessed by relapse or MRI lesions, and decrease with certain disease modifying therapies. <h3>Conclusions:</h3> Heterogeneous methodology limited generalization and meta-analysis. EBV titers are unlikely to represent prognostic biomarkers in MS. The areas of highest promise relate to diagnostic exclusion and pharmacodynamic/disease response. The use of EBV titers as biomarkers in clinical practice remains additionally limited by a lack of methodological precision, reliability, and validation. <b>Disclosure:</b> Dr. Bose has nothing to disclose. Dr. Khalighinejad has nothing to disclose. Dr. Hemond has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for VIVIO Health. Dr. Hemond has stock in VIVIO Health. The institution of Dr. Hemond has received research support from Consorium of Multiple Sclerosis Centers. The institution of Dr. Hemond has received research support from National Multiple Sclerosis Society. The institution of Dr. Hemond has received research support from National Center for Advancing Translational Sciences, National Institutes of Health. The institution of Dr. Hemond has received research support from University of Massachusetts Memorial Medical Center. The institution of Dr. Hemond has received research support from National Institute Of Neurological Disorders And Stroke of the National Institutes of Health. Dr. Hemond has received personal compensation in the range of $0-$499 for serving as a Member of Data Safety and Monitoring Board with National Institute Of Neurological Disorders And Stroke of the National Institutes of Health.

SERTAD3 induces proteasomal degradation of ZIKV capsid protein and represents a therapeutic target.

Zika virus (ZIKV) is a mosquito-borne RNA virus that belongs to the Flaviviridae family. While flavivirus replication is known to occur in the cytoplasm, a significant portion of the viral capsid protein localizes to the nucleus during infection. However, the role of the nuclear capsid is less clear. Herein, we demonstrated SERTA domain containing 3 (SERTAD3) as an antiviral interferon stimulatory gene product had an antiviral ability to ZIKV but not JEV. Mechanistically, we found that SERTAD3 interacted with the capsid protein of ZIKV in the nucleolus and reduced capsid protein abundance through proteasomal degradation. Furthermore, an eight amino acid peptide of SERTAD3 was identified as the minimum motif that binds with ZIKV capsid protein. Remarkably, the eight amino acids synthetic peptide from SERTAD3 significantly prevented ZIKV infection in culture and pregnant mouse models. Taken together, these findings not only reveal the function of SERTAD3 in promoting proteasomal degradation of a specific viral protein but also provide a promising host-targeted therapeutic strategy against ZIKV infection.

The herpes simplex virus tegument protein pUL21 is required for viral genome retention within capsids.

During virion morphogenesis herpes simplex virus nucleocapsids transit from the nucleoplasm to the cytoplasm, through a process called nuclear egress, where the final stages of virion assembly occur. Coupled to nuclear egress is a poorly understood quality-control mechanism that preferentially selects genome-containing C-capsids, rather than A- and B-capsids that lack genomes, for transit to the cytoplasm. We and others have reported that cells infected with HSV strains deleted for the tegument protein pUL21 accumulate both empty A-capsids and C-capsids in the cytoplasm of infected cells. Quantitative microscopy experiments indicated that C-capsids were preferentially selected for envelopment at the inner nuclear membrane and that nuclear integrity remained intact in cells infected with pUL21 mutants, prompting alternative explanations for the accumulation of A-capsids in the cytoplasm. More A-capsids were also found in the nuclei of cells infected with pUL21 mutants compared to their wild type (WT) counterparts, suggesting pUL21 might be required for optimal genome packaging or genome retention within capsids. In support of this, more viral genomes were prematurely released into the cytoplasm during pUL21 mutant infection compared to WT infection and led to enhanced activation of cellular cytoplasmic DNA sensors. Mass spectrometry and western blot analysis of WT and pUL21 mutant capsids revealed an increased association of the known pUL21 binding protein, pUL16, with pUL21 mutant capsids, suggesting that premature and/or enhanced association of pUL16 with capsids might result in capsid destabilization. Further supporting this idea, deletion of pUL16 from a pUL21 mutant strain rescued genome retention within capsids. Taken together, these findings suggest that pUL21 regulates pUL16 addition to nuclear capsids and that premature, and/or, over-addition of pUL16 impairs HSV genome retention within capsids.

Abstract 10847: Tolerability of Sars-cov-2 Mrna Vaccines and Infection for Patients With History of Kawasaki Disease

Introduction: Kawasaki disease (KD) and multisystem inflammatory syndrome in children from COVID-19 infections share overlapping symptoms, suggesting KD patients may be at risk for adverse outcomes from exposure to SARS-CoV-2 mRNA vaccine or infection. Through retrospective review of clinical outcome data, we determined tolerance of KD patients to SARS-CoV-2 antigen exposure. Methods: We evaluated two cohorts using an existing KD database of 826 patients and reviewed individual electronic medical records for the period spanning January 2020 through Jan 2022 via Epic Care Everywhere which includes Washington State immunization records. Vaccine cohort inclusion criteria were (1) age &amp;lt 21 years at immunization and (2) received one or more Pfizer-BioNTech or Moderna vaccine doses. The COVID-19 infection cohort included (1) age &amp;lt 21 years and (2) positive SARS-CoV-2 PCR or nuclear capsid IgG. Results: The vaccine cohort contained 153 patients with vaccine distribution by age subgroups shown in Figure 1. Pfizer-BioNTech vaccine was provided for 93.5% and the remaining received Moderna or a combination. 84.3% were fully vaccinated or received a third-dose booster. No clinically severe adverse events occurred including no vaccine-related hospitalizations or outpatient visits. The COVID-19 infection cohort included thirty-seven patients. No patients required hospitalization. The most common symptoms included low grade fever, fatigue, cough, and myalgia with resolution within a few days. Two patients, 9 and 19 years, had extended cough and fatigue for 3-4 weeks. One patient developed COVID-19 within 6 weeks of receiving IVIG for KD. Conclusions: COVID-19 infections and vaccinations are well tolerated in patients with preceding KD. No severe complications occurred in either cohort with only two patients exhibiting prolonged mild symptoms from COVID-19. This study provides assurance regarding vaccine safety and COVID-19 severity for parents of children with KD.

A Unique Role of the Human Cytomegalovirus Small Capsid Protein in Capsid Assembly.

ABSTRACTMorphogenesis of herpesvirus particles is highly conserved; however, the capsid assembly and genome packaging of human cytomegalovirus (HCMV) exhibit unique features. Examples of these include the essential role of the small capsid protein (SCP) and the existence of the β-herpesvirus-specific capsid-associated protein pp150. SCP and pp150, as well as the UL77 and UL93 proteins, are important capsid constituents, yet their precise mechanism of action is elusive. Here, we analyzed how deletion of the open reading frames (ORFs) encoding pUL77, pUL93, pp150, or SCP affects the protein composition of nuclear capsids. This was achieved by generating HCMV genomes lacking the respective genes, combined with a highly efficient transfection technique that allowed us to directly analyze these mutants in transfected cells. While no obvious effects were observed when pUL77, pUL93, or pp150 was missing, the absence of SCP impeded capsid assembly due to strongly reduced amounts of major capsid protein (MCP). Vice versa, when MCP was lacking, SCP became undetectable, indicating a mutual dependence of SCP and MCP for establishing appropriate protein levels. The SCP domain mediating stable MCP levels could be narrowed down to a C-terminal helix known to convey MCP binding. Interestingly, an SCP-EGFP (enhanced green fluorescent protein) fusion protein which also impaired the production of infectious progeny acted in a different manner, as capsid assembly was not abolished; however, SCP-EGFP-harboring capsids were devoid of DNA and trapped in paracrystalline nuclear structures. These results indicate that SCP is essential in HCMV because of its impact on MCP levels and reveal SCP as a potential target for antiviral inhibitors.

Nuclear entry and egress of parvoviruses.

Parvoviruses are small non-enveloped single-stranded DNA viruses, which depend on host cell nuclear transcriptional and replication machinery. After endosomal exposure of nuclear localization sequence and a phospholipase A2 domain on the capsid surface, and escape into the cytosol, parvovirus capsids enter the nucleus. Due to the small capsid diameter of 18-26 nm, intact capsids can potentially pass into the nucleus through nuclear pore complexes (NPCs). This might be facilitated by active nuclear import, but capsids may also follow an alternative entry pathway that includes activation of mitotic factors and local transient disruption of the nuclear envelope. The nuclear entry is followed by currently undefined events of viral genome uncoating. After genome release, viral replication compartments are initiated and infection proceeds. Parvoviral genomes replicate during cellular S phase followed by nuclear capsid assembly during virus-induced S/G2 cell cycle arrest. Nuclear egress of capsids occurs upon nuclear envelope degradation during apoptosis and cell lysis. An alternative pathway for nuclear export has been described using active transport through the NPC mediated by the chromosome region maintenance 1 protein, CRM1, which is enhanced by phosphorylation of the N-terminal domain of VP2. However, other alternative but not yet uncharacterized nuclear export pathways cannot be excluded.

Direct Capsid Labeling of Infectious HIV-1 by Genetic Code Expansion Allows Detection of Largely Complete Nuclear Capsids and Suggests Nuclear Entry of HIV-1 Complexes via Common Routes.

ABSTRACTThe cone-shaped mature HIV-1 capsid is the main orchestrator of early viral replication. After cytosolic entry, it transports the viral replication complex along microtubules toward the nucleus. While it was initially believed that the reverse transcribed genome is released from the capsid in the cytosol, recent observations indicate that a high amount of capsid protein (CA) remains associated with subviral complexes during import through the nuclear pore complex (NPC). Observation of postentry events via microscopic detection of HIV-1 CA is challenging, since epitope shielding limits immunodetection and the genetic fragility of CA hampers direct labeling approaches. Here, we present a minimally invasive strategy based on genetic code expansion and click chemistry that allows for site-directed fluorescent labeling of HIV-1 CA, while retaining virus morphology and infectivity. Thereby, we could directly visualize virions and subviral complexes using advanced microscopy, including nanoscopy and correlative imaging. Quantification of signal intensities of subviral complexes revealed an amount of CA associated with nuclear complexes in HeLa-derived cells and primary T cells consistent with a complete capsid and showed that treatment with the small molecule inhibitor PF74 did not result in capsid dissociation from nuclear complexes. Cone-shaped objects detected in the nucleus by electron tomography were clearly identified as capsid-derived structures by correlative microscopy. High-resolution imaging revealed dose-dependent clustering of nuclear capsids, suggesting that incoming particles may follow common entry routes.

Tolerability of COVID-19 Infection and Messenger RNA Vaccination Among Patients With a History of Kawasaki Disease

Kawasaki disease (KD) symptoms significantly overlap with multisystem inflammatory syndrome in children due to COVID-19. Patients with KD may be at risk for adverse outcomes from exposure to SARS-CoV-2 infection or vaccination. To describe the outcomes of patients with KD to SARS-CoV-2 infection or vaccination. This case series evaluated 2 cohorts using an existing KD database and reviewed individual electronic medical records for the period spanning January 1, 2020, through January 31, 2022, via electronic medical records that include Washington state immunization records. Vaccine cohort inclusion criteria consisted of being 21 years or younger at immunization and receiving 1 or more BNT162b2 (Pfizer-BioNTech) or messenger RNA (mRNA)-1273 (Moderna) vaccine doses. The COVID-19 cohort included patients 21 years or younger with positive polymerase chain reaction or nuclear capsid IgG findings for SARS-CoV-2. Participants included 826 patients from a preexisting KD database. One hundred fifty-three patients received at least 1 BNT162b2 or mRNA-1273 vaccine dose and were included in the mRNA vaccine cohort. Thirty-seven patients had positive test results for SARS-CoV-2 and were included in the COVID-19 cohort. SARS-CoV-2 vaccination and/or infection. Adverse events after mRNA vaccination and/or COVID-19, including clinician visits, emergency department encounters, or hospitalizations. Among the 153 patients included in the mRNA vaccination cohort (mean [SD] age, 13.0 [4.3] years; 94 male [61.4%]), the BNT162b2 vaccine was provided for 143 (93.5%), and the remaining 10 (6.5%) received mRNA-1273 or a combination of both. Among patients in the vaccine cohort, 129 (84.3%) were fully vaccinated or received a third-dose booster. No clinically severe adverse events occurred, and there were no reports of vaccine-related hospitalizations or outpatient visits. The COVID-19 cohort included 37 patients (mean [SD] age, 11.0 [5.5] years; 22 male [59.5%]). No patients required hospitalization due to COVID-19. The most common symptoms included low-grade fever, fatigue, cough, and myalgia with resolution within a few days. Two patients, aged 9 and 19 years, had extended cough and fatigue for 3 to 4 weeks. One patient developed COVID-19 within 6 weeks of receiving intravenous immunoglobulin for KD. These findings suggest that the mRNA vaccines may be safe and COVID-19 may not be severe for patients with a history of KD.

'Come together'-The Regulatory Interaction of Herpesviral Nuclear Egress Proteins Comprises Both Essential and Accessory Functions.

Herpesviral nuclear egress is a fine-tuned regulatory process that defines the nucleocytoplasmic release of viral capsids. Nuclear capsids are unable to traverse via nuclear pores due to the fact of their large size; therefore, herpesviruses evolved to develop a vesicular transport pathway mediating the transition across the two leaflets of the nuclear membrane. The entire process involves a number of regulatory proteins, which support the local distortion of the nuclear envelope. In the case of the prototype species of β-Herpesvirinae, the human cytomegalovirus (HCMV), the nuclear egress complex (NEC) is determined by the core proteins pUL50 and pUL53 that oligomerize, form capsid docking lattices and mediate multicomponent assembly with NEC-associated viral and cellular proteins. The NEC-binding principle is based on the hook-into-groove interaction through an N-terminal hook-like pUL53 protrusion that embraces an α-helical pUL50 binding groove. Thus far, the function and characteristics of herpesviral core NECs have been well studied and point to the groove proteins, such as pUL50, as the multi-interacting, major determinants of NEC formation and egress. This review provides closer insight into (i) sequence and structure conservation of herpesviral core NEC proteins, (ii) experimentation on cross-viral core NEC interactions, (iii) the essential functional roles of hook and groove proteins for viral replication, (iv) an establishment of assay systems for NEC-directed antiviral research and (v) the validation of NEC as putative antiviral drug targets. Finally, this article provides new insights into the conservation, function and antiviral targeting of herpesviral core NEC proteins and, into the complex regulatory role of hook and groove proteins during the assembly, egress and maturation of infectious virus.

UL34 Deletion Restricts Human Cytomegalovirus Capsid Formation and Maturation.

Over 50% of the world’s population is infected with Human Cytomegalovirus (HCMV). HCMV is responsible for serious complications in the immuno-compromised and is a leading cause of congenital birth defects. The molecular function of many HCMV proteins remains unknown, and a deeper understanding of the viral effectors that modulate virion maturation is required. In this study, we observed that UL34 is a viral protein expressed with leaky late kinetics that localises to the nucleus during infection. Deletion of UL34 from the HCMV genome (ΔUL34) did not abolish the spread of HCMV. Instead, over >100-fold fewer infectious virions were produced, so we report that UL34 is an augmenting gene. We found that ΔUL34 is dispensable for viral DNA replication, and its absence did not alter the expression of IE1, MCP, gB, UL26, UL83, or UL99 proteins. In addition, ΔUL34 infections were able to progress through the replication cycle to form a viral assembly compartment; however, virion maturation in the cytoplasm was abrogated. Further examination of the nucleus in ΔUL34 infections revealed replication compartments with aberrant morphology, containing significantly less assembled capsids, with almost none undergoing subsequent maturation. Therefore, this work lays the foundation for UL34 to be further investigated in the context of nuclear organization and capsid maturation during HCMV infection.

A multiscale coarse-grained model of the nuclear pore complex and HIV-1 capsid interaction

The docking of the HIV-1 capsid at the nuclear pore complex, penetration of the viral capsid, and subsequent nuclear uncoating kinetics are critical HIV host-cell interactions that are yet to be understood. A particular challenge in this regard, is the computational modeling of the nuclear pore complex (NPC), a large macromolecular complex in the cell that regulates transport into and out of the nucleus. Computer simulations of complete nuclear pore complex can provide theoretical insights into large-scale viral processes pertaining to capsid entry.

Review of Direct capsid labeling of infectious HIV-1 by genetic code expansion allows detection of largely complete nuclear capsids and suggests nuclear entry of HIV-1 complexes via common routes

Review of Direct capsid labeling of infectious HIV-1 by genetic code expansion allows detection of largely complete nuclear capsids and suggests nuclear entry of HIV-1 complexes via common routes