Cholesterol depletion inhibits rabies virus infection by restricting viral adsorption and fusion.

Rabies is an ancient zoonotic disease caused by the rabies virus (RABV), and a sharp increase in rabies cases and deaths were observed following the COVID-19 pandemic, indicating that it still poses a severe public health threat in most countries in the world. Cholesterol is one of the major lipid components in cells, and the exact role of cholesterol in RABV infection remains unclear. In this study, we initially observed that cellular cholesterol levels were significantly elevated in RABV infected cells, while cholesterol depletion by using methyl-ß-cyclodextrin (MßCD) could restrict RABV entry. We further found that decreasing the cholesterol level of the viral envelope could change the bullet-shaped morphology of RABV and dislodge the glycoproteins on its surface to affect RABV entry. Moreover, the depletion of cholesterol could decrease lysosomal cholesterol accumulation to inhibit RABV fusion. Finally, it was found that the depletion of cholesterol by MßCD was due to the increase of oxygen sterol production in RABV-infected cells and the enhancement of cholesterol efflux by activating liver X receptor alpha (LXRα). Together, our study reveals a novel role of cholesterol in RABV infection, providing new insight into explore of effective therapeutics for rabies.

A broadly applicable protein-polymer adjuvant system for antiviral vaccines.

Although protein subunit vaccines generally have acceptable safety profiles with precise antigenic content, limited immunogenicity can lead to unsatisfactory humoral and cellular immunity and the need for vaccine adjuvants and delivery system. Herein, we assess a vaccine adjuvant system comprising Quillaja Saponaria-21(QS-21) and cobalt porphyrin polymeric micelles that enabling the display of His-tagged antigen on its surface. The nanoscale micelles promote antigen uptake and dendritic cell activation to induce robust cytotoxic T lymphocyte response and germinal center formation. Using the recombinant protein antigens from influenza A and rabies virus, the micelle adjuvant system elicited robust antiviral responses and protected mice from lethal challenge. In addition, this system could be combined with other antigens to induce high titers of neutralizing antibodies in models of three highly pathogenic viral pathogens: Ebola virus, Marburg virus, and Nipah virus. Collectively, our results demonstrate this polymeric micelle adjuvant system can be used as a potent nanoplatform for developing antiviral vaccine countermeasures that promote humoral and cellular immunity.