Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can cause a wide range of neurologic complications; however, its neuropenetrance during the acute phase of the illness is unknown.
Extracellular vesicles were isolated from brain biopsy tissue from a patient undergoing epilepsy surgery using ultracentrifugation and analyzed by Western blot and qPCR for the presence of virus protein and RNA, respectively. Biopsy tissue was assessed by immunohistochemistry for the presence of microvascular damage and compared with 3 other non-COVID surgical epilepsy brain tissues.
We demonstrate the presence of viral nucleocapsid protein in extracellular vesicles and microvascular disease in the brain of a patient undergoing epilepsy surgery shortly after SARS-CoV-2 infection. Endothelial cell activation was indicated by increased levels of platelet endothelial cell adhesion molecule-1 and was associated with fibrinogen leakage and immune cell infiltration in the biopsy tissue as compared with control non-COVID surgical epilepsy brain tissues.
Despite the lack of evidence of viral replication within the brain, the presence of the nucleocapsid protein was associated with disease-specific endothelial cell activation, fibrinogen leakage, and immune cell infiltration.

The World Health Organization has defined long COVID-19 (LC) as a condition that occurs in individuals with a history of SARS-CoV-2 infection who exhibit persistent symptoms after its acute phase that last for at least two months and cannot be explained by an alternative diagnosis. Since we had previously reported residual viral antigens in tissues of convalescent patients, we aimed to assess the presence of such antigens in long COVID tissues. Here, we established the presence of the residual virus in the appendix, skin, and breast tissues of 2 patients who exhibited LC symptoms 163 and 426 days after symptom onset. With multiplex immunohistochemistry, we detected viral nucleocapsid protein in all three tissues. The nucleocapsid protein was further observed to colocalize with macrophage marker CD68, suggesting that immune cells were direct targets of SARS-CoV-2. Additionally, using RNAscope, the presence of viral RNA was also detected. Our positive finding in the breast tissue is corroborated by the recent reports of immunocompromised patients experiencing LC symptoms and persistent viral replication. Overall, our findings and emerging LC studies raise the possibility that the gastrointestinal tract may function as a reservoir for SARS-CoV-2.

The nature of specific RNA-RNA and protein-RNA interactions involved in the process of genome dimerization and isomerization in HIV-1, which is mediated in vitro by stemloop 1 (SL1) of the packaging signal and by the nucleocapsid (NC) domain of the viral Gag polyprotein, was investigated by using archetypical nucleic acid ligands as noncovalent probes. Small-molecule ligands make contact with their target substrates through complex combinations of H-bonds, salt bridges, and hydrophobic interactions. Therefore, their binding patterns assessed by electrospray ionization mass spectrometry can provide valuable insights into the factors determining specific recognition between species involved in biopolymer assemblies. In the case of SL1, dimerization and isomerization create unique structural features capable of sustaining stable interactions with classic nucleic acid ligands. The binding modes exhibited by intercalators and minor groove binders were adversely affected by the significant distortion of the duplex formed by palindrome annealing in the kissing-loop (KL) dimer, whereas the modes observed for the corresponding extended duplex (ED) confirmed a more regular helical structure. Consistent with the ability to establish electrostatic interactions with highly negative pockets typical of helix anomalies, polycationic aminoglycosides bound to the stem-bulge motif conserved in all SL1 conformers, to the unpaired nucleotides located at the hinge between kissing hairpins in KL, and to the exposed bases flanking the palindrome duplex in ED. The patterns afforded by intercalators and minor groove binders did not display detectable variations when the corresponding NC-SL1 complexes were submitted to probing. In contrast, aminoglycosides displayed the ability to compete with the protein for overlapping sites, producing opposite effects on the isomerization process. Indeed, displacing NC from the stem-bulges of the KL dimer induced inhibition of stem melting and decreased the efficiency of isomerization. Competition for the hinge region, instead, eliminated the NC stabilization of a grip motif formed by nucleobases of opposite strands, thus facilitating the strand-exchange required for isomerization. These noncovalent probes provided further evidence that the structural context of the actual binding sites has significant influence on the chaperone activities of NC, which should be taken in account when developing potential drug candidates aimed at disrupting genome dimerization and isomerization in HIV-1.

The order Nidovirales, which includes the arteriviruses and coronaviruses, incorporate a cytoplasmic replication scheme; however, the nucleocapsid (N) protein of several members of this group localizes to the nucleolus suggesting that viral proteins influence nuclear processes during replication. The relatively small, 123 amino acid, N protein of porcine reproductive and respiratory syndrome virus (PRRSV), an arterivirus, presents an ideal model system for investigating the properties and mechanism of N protein nucleolar localization. The PRRSV N protein is found in both cytoplasmic and nucleolar compartments during infection and after transfection of gene constructs that express N-enhanced green fluorescent protein (EGFP) fusion proteins. Experiments using oligopeptides, truncated polypeptides and amino acid-substituted proteins have identified several domains within PRRSV N protein that participate in nucleo-cytoplasmic shuttling, including a cryptic nuclear localization signal (NLS) called NLS-1, a functional NLS (NLS-2), a nucleolar localization sequence (NoLS), as well as a possible nuclear export signal (NES). The purpose of this paper is to review our current understanding of PRRSV N protein shuttling and propose a shuttling scheme regulated by RNA binding and post-translational modification.

In May of 2001 a Nigerian woman visiting the United Kingdom presented with fever, headache and difficulty swallowing. Within 24 h she showed a marked deterioration and died shortly afterwards. Autopsy samples from a range of tissues were analysed to confirm a clinical diagnosis of rabies. Phylogenetic analysis of the viral nucleoprotein gene confirmed that this was an infection with a genotype 1 virus (classical rabies) belonging to the Africa 2 group, which is endemic in Northern Africa. Comparison of both the nucleoprotein and glycoprotein coding sequences of this isolate with an imported case of human rabies from 1996, also from Nigeria, showed that the two viruses were 99% homologous.

Follicular dendritic cells (FDC) from axillary lymphoid tissue of a patient with acquired immune deficiency syndrome (AIDS) were analyzed for the presence of gag and env proteins and env mRNA of human immunodeficiency virus type-1 (HIV-1), both in a purified FDC suspension and on frozen sections. Isolated cells with morphologic and immunocytochemical features of FDC expressed HIV-1 core (gag) proteins p15, p17, p24, and envelope (env) protein gp41; in addition HIV-1 env mRNA was detected in some of these cells. This corresponded with intense expression of HIV-1 proteins by FDC in germinal centers in situ, and the presence of HIV-1 mRNA-positive cells in germinal follicles. These findings led us to conclude that FDC are infected and able to produce HIV-1. Such infection may contribute significantly to the destruction of the FDC network during the lymphadenopathy phase after HIV-1 infection.