New Bat-Borne Filovirus Identified in China

Investigators have identified a new filovirus in a Rousettus bat in China, stoking public fear of potential transmission to humans.

The new virus—Mengla virus—was discovered by a team of investigators from Singapore’s Duke-NUS Medical School, in collaboration with scientists in China, while they were analyzing the diversity of filoviruses in Rousettus bats. It was detected from a bat sample and investigators conducted sequencing and functional characterization studies to learn more about it. Their findings were published in the journal Nature Microbiology.

“As for all members of the filovirus family, the number one threat is its potential transmission to humans, with severe disease-causing capability,” Linfa Wang, PhD, professor and director of the emerging infectious diseases program, Duke-NUS Medical School, and senior author on the study, told Contagion® in an interview. “[The disease-causing capability of the Mengla virus] is not known at the present time but we need to keep a close watch on this.”

The Mengla virus was found to be genetically distinct from other filoviruses, with the complete genome of the virus sharing 32% to 54% nucleotide sequence identity with other known filoviruses. Additionally, the virus has only been detected in China, which is a different geographic location than other filoviruses.

Phylogenetic analysis placed the virus between Ebola and Marburg viruses, which investigators indicate suggests the need for a new genus taxon. The new genus, named Dianlovirus, could potentially include more than 1 species and is located between Ebolavirus and Marburgvirus on the filovirus evolutionary tree.

Investigators also determined that the Mengla virus is capable of using the Niemann Pick C1 as an entry receptor to cells despite the low amino acid sequence identity (22%-39%) of the glycoprotein with other filoviruses.

According to Dr. Wang, the investigators were unable to determine if the unique genetic traits will evolve into functioning traits that differ from other filoviruses.

“The virus has sufficient genetic divergence from the best-known members of the filovirus family, Ebola and Marburg, to warrant the classification into a separate genus,” Dr. Wang explained. “Yet, it seems to be able to use a highly conserved cellular entry mechanism than other filoviruses. At this stage, it is too early to predict whether the Mengla virus’s unique genetic traits will manifest into functionally different traits as well.”

Dr. Wang also explained to Contagion® that it is unknown whether or not the Ebola vaccines currently in trials will be able to protect against Mengla virus infection. Sequencing data predicts that cross-protection will be low, indicating that the Mengla virus could be a serious threat to humans if interspecies transmission does occur.

At this time, the virus has only been identified in Rousettus bats in China and the investigators indicated that further testing is necessary to assess the possibility and risk of interspecies transmission.

Dr. Wang told Contagion® that at this time the investigators are focusing on a set of immediate priorities to study the pathogenesis of the virus.

Thus far, the team has obtained a genome blueprint of the virus and has shifted their priorities to work on isolating or engineering a live virus. Once the virus is obtained, investigators will conduct infections studies in containment facilities to identify the host tropism and pathogenesis potential in nonhuman primates.

After the pathogenesis potential in nonhuman primates is identified, the team’s research will shift to assessing the risk of transmission to humans from various hosts. Once the risk is identified the investigators will shift their focus on conducting targeted surveillance for the virus in high-risk areas.

According to the investigators, this discovery provides further evidence that bats can harbor a variety of diverse filoviruses across a wide range of locations globally, demonstrating the need to continue to study bats and bat-borne filoviruses.