Mojiang And Other Henipaviruses 

The Mojiang virus is a member of the henipaviruses genus in the Paramyxoviridae family, known for its ability to cause severe neurological and respiratory illnesses in humans and animals. However, no viral isolates of the Mojiang virus have been recovered to date. Its existence is solely known from DNA sequence data, leaving the potential for disease-causing effects of this henipavirus uncertain.

Overview

In 2012, researchers identified a previously unknown paramyxovirus carried by rats named the Mojiang henipavirus (MojV). This discovery followed the deaths of three miners who had suffered from severe pneumonia of unknown origin. Specimens collected from bats, rats, and musk shrews within a cave in Mòjiang Hani Autonomous County, China, where the victims likely contracted the disease, were analysed. Genome analysis of MojV revealed its close relationship to viruses within the Henipavirus genus. However, no physical samples of the Mojiang virus have been isolated yet, and its potential to cause disease in humans remains unknown.^1,4  

The article discusses MojV and other henipaviruses, their transmission methods, and preventive measures against infections.

MojV falls within the genus of henipaviruses in the Paramyxoviridae family, and it is known for causing severe neurological and respiratory illnesses in both humans and animals. There are eight recognised members within this genus, including Hendra virus, Nipah virus, Cedar virus, Gamak virus, Daeryong virus, Kumasi virus, and the recently discovered Angavokely virus and Langya virus. Among these henipaviruses, four can spread from animals to humans. Hendra virus and Nipah virus, prevalent in Australia, Malaysia, India, and Bangladesh, can lead to severe acute respiratory distress and high mortality rates in humans. Mojiang virus and Langya virus, primarily found in China's Yunnan, Henan, and Shandong provinces, can cause fever and respiratory distress in humans, indicating their ability to spread from animals to humans.

Henipaviruses, including the Mojiang virus, infect host cells using specific attachment and fusion glycoproteins on their surface.^2,3  

The MojV attachment glycoprotein, typically responsible for cell entry in similar viruses, is missing a vital feature known as the ephrin binding motif. This motif is essential for recognising receptors on our cell surfaces. MojV doesn't appear to bind to ephrin-B2 or ephrin-B3, common entry receptors for similar viruses, suggesting it may employ an alternative method to enter host cells that do not rely on ephrin.

Moreover, when researchers conducted large-scale serological screening studies to search for antibodies against known similar viruses, they couldn't find any that interacted with MojV. This means that standard blood tests using antibodies from these viruses might have missed detecting Mojiang viruses. As a result, MojV could be more prevalent than previously thought.⁴  

Transmission of henipaviruses

While information regarding the transmission of Cedar virus, Kumasi bat virus, or MojV is currently unavailable, it is known that henipaviruses like Hendra virus and Nipah virus can spread among bats, horses, pigs, and humans.⁵ 

Hendra virus spreads to humans through direct contact with infected horses, bodily fluids, or tissues of infected horses. Horses become infected through contact with bat urine. The Hendra virus does not pass from person to person or from bat to human.

The Nipah virus spreads through contact with infected pigs or bats. Another route of exposure is consuming date palm sap or fallen fruit contaminated with bat excretions. Person-to-person transmission has been reported through contact with infected individuals, including respiratory droplets. The transmission of the Nipah Virus is facilitated by cultural and healthcare practices in which friends and family members care for sick patients.

In the first round of sampling, the Langya virus was mainly found in shrews, with 71 out of 262 sampled (26%) being positive. The small shrew animals found to host the Langya virus belonged to the Crocidura lasiura and Crocidura shantungensis species. Further research is needed to conclusively identify the natural animal reservoirs, susceptible species, and transmission pathways to humans. Current evidence does not indicate person-to-person transmission of the Langya virus.⁶ 

Symptoms and signs of henipaviruses

The incubation period spans approximately 5 to 16 days, with rare instances of it being less than 2 months. Both Hendra and Nipah virus infections can lead to severe flu-like symptoms such as dizziness, headache, fever, and muscle aches. These illnesses can progress to severe encephalitis, characterised by confusion, abnormal reflexes, seizures, and coma, with respiratory symptoms potentially present. Encephalitis may also reoccur months or years after the initial illness. Hendra virus carries a case-fatality ratio of 57%, with 4 out of 7 known human cases resulting in death. For Nipah virus infection, case-fatality ratios range from 40% to 70%, with some outbreaks experiencing a 100% fatality rate.⁶  

Diagnosis of henipaviruses

Laboratory diagnosis typically involves a combination of tests, such as ELISA of serum or cerebrospinal fluid (CSF); reverse transcription PCR of serum, CSF, or throat swabs; and virus isolation from CSF or throat swabs.⁶ 

Prevention of henipaviruses

 Currently, specific preventive measures tailored specifically for MojV are limited, and further research is needed to develop targeted prevention strategies. However, general advice can be applied to preventing henipavirus infections, such as avoiding contact with potential reservoir hosts like rats and minimising exposure to bat habitats. Also, travellers are advised to refrain from contacting sick horses, pigs, and their excretions. Travellers should also avoid consuming fallen fruit, raw date palm sap, or products made from raw sap. A Hendra virus vaccine for horses has been granted a license in Australia. It shows potential in preventing Henipavirus infections in humans, but no licensed vaccines for humans are presently available.⁶

Summary

Discovered in 2012 in China, the Mojiang virus (MojV) is the first henipavirus found in a rodent, known only through genetic sequences. The Mojiang virus is a member of the henipaviruses genus in the Paramyxoviridae family, known for its ability to cause severe neurological and respiratory illnesses in humans and animals. Among these viruses, Hendra and Nipah virus infections can lead to respiratory distress and high mortality rates. MojV's method of cell entry differs from that of other viruses, suggesting potential variations in its behaviour. While transmission details for MojV are unavailable, Hendra and Nipah viruses spread among bats, horses, pigs, and humans. Laboratory diagnosis of henipaviruses involves several tests, including ELISA and PCR. Symptoms include flu-like symptoms progressing to severe encephalitis. Prevention involves avoiding contact with infected animals and their excretions. Although a Hendra virus vaccine for horses is available, licensed vaccines for humans are not yet accessible.