Scientists Find HBV ‘Navigator’ Protein, New Therapy Ahead
In a breakthrough that solves a 14-year mystery in virology, Chinese researchers have identified a protein that acts as a “navigator” for the Hepatitis B virus (HBV), guiding it through the crowded interior of a liver cell to reach the nucleus where it replicates. The discovery, published in the journal Cell on May 20, opens a promising new avenue for developing curative treatments for chronic Hepatitis B, a disease affecting approximately 250 million people worldwide.
Led by Professor Li Wenhui at the Beijing National Institute of Biological Sciences (NIBS) and Tsinghua University, the team identified SCARF2 (Scavenger receptor class F member 2) as an intracellular receptor that HBV relies on after it enters a liver cell. The research was reported by Guangming Daily on June 2, 2026.
The Viral Journey: From Cell Membrane to Nucleus
When a virus infects a human cell, it first must “swipe its key card” — binding to a specific receptor on the cell membrane to gain entry. For HBV, that first key was discovered by the same research team in 2012: a protein called NTCP (sodium taurocholate cotransporting polypeptide).
But getting inside the cell is only the first step. HBV, like many DNA viruses, must then navigate through the chaotic molecular environment of the cytoplasm to reach the cell nucleus. Only there can it safely release its genome, begin replication, and establish the persistent infection that makes chronic Hepatitis B so difficult to cure.
“The interior of a cell is an extremely crowded, chaotic molecular world,” the researchers noted in their Guangming Daily interview. “Various proteins and organelles shuttle about like commuters during rush hour at a busy transit station.” How the virus finds its way through this molecular chaos has been one of virology’s fundamental unanswered questions — until now.
SCARF2: The Missing Navigator
The newly discovered SCARF2 protein, as described in the Cell paper, functions as an intracellular receptor that binds to HBV after the virus has entered the cell via NTCP. Using high-precision imaging techniques including live-cell tracking and super-resolution microscopy, the team observed that NTCP and SCARF2 come into close proximity inside the cell after HBV infection.
SCARF2 belongs to the scavenger receptor class F family and is a single-pass transmembrane protein. Its N-terminal region contains EGF-like domains 4-6 that bind to a specific region (amino acids 79-108) of the HBV large envelope protein, while its C-terminal domain features intrinsically disordered regions that may facilitate the release of the viral nucleocapsid through a process called liquid-liquid phase separation.
To confirm SCARF2’s critical role, the team mutated key amino acids (positions 89/90) on the virus surface where SCARF2 binds. The mutated virus could no longer effectively bind to SCARF2, and its infection efficiency dropped dramatically. Further experiments showed that when SCARF2 was knocked down in cells, the virus became trapped in transport vesicles and lost its ability to infect, as detailed in the Tsinghua University press release.
Building on a Legacy of Discovery
This finding represents the second major breakthrough from Li Wenhui’s laboratory in the fight against Hepatitis B. In 2012, the team discovered NTCP, the cell surface receptor that HBV uses to enter liver cells — a landmark achievement that enabled laboratory studies of HBV infection for the first time.
That earlier discovery has already yielded tangible treatments. In January 2026, libevetamab, an antibody drug based on the NTCP discovery, received conditional approval in China for treating Hepatitis D virus (HDV), a related infection that occurs alongside HBV. The drug’s first prescription was filled at Beijing Friendship Hospital in March 2026, as People’s Daily reported.
“With breakthroughs in basic research, the application of results is an inevitable direction,” Li Wenhui told People’s Daily. “In the long run, basic research that withstands the test of time will certainly improve human well-being.”
Implications for Curative Treatments
The discovery of SCARF2 is particularly significant because current treatments for chronic Hepatitis B — nucleoside analogs and interferons — can suppress viral replication but rarely achieve a complete cure. Patients typically require lifelong medication.
SCARF2 represents a new drug target. By blocking this navigator protein, future therapies could prevent HBV from ever reaching the nucleus, potentially achieving what researchers call a “functional cure” — the elimination of the virus’s ability to establish chronic infection. Combined with existing antivirals that suppress replication, a SCARF2-targeting drug could offer a one-two punch against the virus.
According to the ScienceNet summary, the study reveals not just a key step in HBV’s “nuclear voyage” but also uncovers a previously unknown mechanism of directed intracellular transport — a fundamental discovery in cell biology that may apply to other viruses that need to reach the nucleus.
What’s Next
While the discovery is scientifically profound, translating it into clinical treatments will take time. Key questions remain: Can SCARF2 be effectively targeted by small molecule drugs or biologics? Does the protein play a role in other viral infections? And will targeting SCARF2 in humans have side effects given its normal cellular functions?
Li Wenhui’s team has demonstrated a proven track record of moving from basic discovery to approved drugs — the NTCP-to-libevetamab pipeline took approximately 14 years. With the SCARF2 discovery, the clock starts ticking on what could be the next generation of Hepatitis B therapies.
As Guangming Daily eloquently described it: “This new discovery is like a detailed new map, guiding scientists to explore the unknown world inside cells, and lighting a new beacon for ultimately conquering Hepatitis B and developing curative drugs.”