A Review of Hendra Virus and Nipah Virus Infections in Man and Other Animals

Recuperative potential of Indian medicinal plant compounds- a tool to encumber henipaviruses: an in -silico study

Henipaviruses, highly fatal zoonotic viruses with mortality rates up to 100%, pose a significant threat to humans. Despite sporadic cases, including infections from Cedar, Langya, and Nipah Viruses, there are no established drugs or vaccines for treatment. This lack of specific medication led us to explore 57 non-toxic compounds from Indian Medicinal Plants, selected from 232 compounds, aiming to combat these viruses. Through in silico ADMET analyses, Three compounds-andrographolide, pterygospermin and Salidroside-stood out for their exceptional non-toxic properties. These compounds underwent in silico target prediction, molecular docking and dynamics with Cedar, Langya, and Nipah Virus proteins from the Protein Data Bank. Among them, Andrographolide displayed the most promising negative free energy scores and stability in Cedar Virus-Attachment G-Protein binding pockets. Pterygospermin and Salidroside showed efficacy against Langya and Nipah Virus target proteins throughout the simulation. These compounds not only exhibited antiviral properties but also demonstrated immunomodulatory, anti-inflammatory, and hepatoprotective effects by our in-silico studies. Their potential as treatments or preventive measures against henipaviral infections makes them promising candidates for further research and development.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-024-00236-x.

Animal Models for Henipavirus Research

Hendra virus (HeV) and Nipah virus (NiV) are zoonotic paramyxoviruses in the genus Henipavirus (HNV) that emerged nearly thirty years ago. Outbreaks of HeV and NiV have led to severe respiratory disease and encephalitis in humans and animals characterized by a high mortality rate. Despite the grave threat HNVs pose to public health and global biosecurity, no approved medical countermeasures for human use currently exist against HeV or NiV. To develop candidate vaccines and therapeutics and advance the field's understanding of HNV pathogenesis, animal models of HeV and NiV have been instrumental and remain indispensable. Various species, including rodents, ferrets, and nonhuman primates (NHPs), have been employed for HNV investigations. Among these, NHPs have demonstrated the closest resemblance to human HNV disease, although other animal models replicate some key disease features. Here, we provide a comprehensive review of the currently available animal models (mice, hamsters, guinea pigs, ferrets, cats, dogs, nonhuman primates, horses, and swine) to support HNV research. We also discuss the strengths and limitations of each model for conducting pathogenesis and transmission studies on HeV and NiV and for the evaluation of medical countermeasures.

Henipavirus zoonosis: outbreaks, animal hosts and potential new emergence

Hendra virus (HeV) and Nipah virus (NiV) are biosafety level 4 zoonotic pathogens causing severe and often fatal neurological and respiratory disease. These agents have been recognized by the World Health Organization as top priority pathogens expected to result in severe future outbreaks. HeV has caused sporadic infections in horses and a small number of human cases in Australia since 1994. The NiV Malaysia genotype (NiV-M) was responsible for the 1998-1999 epizootic outbreak in pigs with spillover to humans in Malaysia and Singapore. Since 2001, the NiV Bangladesh genotype (NiV-B) has been the predominant strain leading to outbreaks almost every year in Bangladesh and India, with hundreds of infections in humans. The natural reservoir hosts of HeV and NiV are fruit bats, which carry the viruses without clinical manifestation. The transmission pathways of henipaviruses from bats to humans remain poorly understood. Transmissions are often bridged by an intermediate animal host, which amplifies and spreads the viruses to humans. Horses and pigs are known intermediate hosts for the HeV outbreaks in Australia and NiV-M epidemic in Malaysia and Singapore, respectively. During the NiV-B outbreaks in Bangladesh, following initial spillover thought to be through the consumption of date palm sap, the spread of infection was largely human-to-human transmission. Spillover of NiV-B in recent outbreaks in India is less understood, with the primary route of transmission from bat reservoir to the initial human infection case(s) unknown and no intermediate host established. This review aims to provide a concise update on the epidemiology of henipaviruses covering their previous and current outbreaks with emphasis on the known and potential role of livestock as intermediate hosts in disease transmission. Also included is an up-to-date summary of newly emerging henipa-like viruses and animal hosts. In these contexts we discuss knowledge gaps and new challenges in the field and propose potential future directions.

Inactivation Methods for Experimental Nipah Virus Infection

Nipah virus (NiV) is an emerging zoonotic paramyxovirus that causes severe disease in humans and livestock. Due to its high pathogenicity in humans and the lack of available vaccines and therapeutics, NiV needs to be handled in biosafety level 4 (BSL-4) laboratories. Safe inactivation of samples containing NiV is thus necessary to allow further processing in lower containment areas. To date, there is only limited information available on NiV inactivation methods validated by BSL-4 facilities that can be used as a reference. Here, we compare some of the most common inactivation methods in order to evaluate their efficacy at inactivating NiV in infected cells, supernatants and organs. Thus, several physical and chemical inactivation methods, and combinations thereof, were assessed. Viral replication was monitored for 3 weeks and NiV presence was assessed by RT-qPCR, plaque assay and indirect immunofluorescence. A total of nineteen methods were shown to reduce NiV infectious particles in cells, supernatants and organs to undetectable levels. Therefore, we provide a list of methods for the safe and efficient inactivation of NiV.

Henipavirus Immune Evasion and Pathogenesis Mechanisms: Lessons Learnt from Natural Infection and Animal Models

Nipah henipavirus (NiV) and Hendra henipavirus (HeV) are zoonotic emerging paramyxoviruses causing severe disease outbreaks in humans and livestock, mostly in Australia, India, Malaysia, Singapore and Bangladesh. Both are bat-borne viruses and in humans, their mortality rates can reach 60% in the case of HeV and 92% for NiV, thus being two of the deadliest viruses known for humans. Several factors, including a large cellular tropism and a wide zoonotic potential, con-tribute to their high pathogenicity. This review provides an overview of HeV and NiV pathogenicity mechanisms and provides a summary of their interactions with the immune systems of their different host species, including their natural hosts bats, spillover-hosts pigs, horses, and humans, as well as in experimental animal models. A better understanding of the interactions between henipaviruses and their hosts could facilitate the development of new therapeutic strategies and vaccine measures against these re-emerging viruses.

Utilization of Viral Vector Vaccines in Preparing for Future Pandemics

As the global response to COVID-19 continues, government stakeholders and private partners must keep an eye on the future for the next emerging viral threat with pandemic potential. Many of the virus families considered to be among these threats currently cause sporadic outbreaks of unpredictable size and timing. This represents a major challenge in terms of both obtaining sufficient funding to develop vaccines, and the ability to evaluate clinical efficacy in the field. However, this also presents an opportunity in which vaccines, along with robust diagnostics and contact tracing, can be utilized to respond to outbreaks as they occur, and limit the potential for further spread of the disease in question. While mRNA-based vaccines have proven, during the COVID-19 response, to be an effective and safe solution in terms of providing a rapid response to vaccine development, virus vector-based vaccines represent a class of vaccines that can offer key advantages in certain performance characteristics with regard to viruses of pandemic potential. Here, we will discuss some of the key pros and cons of viral vector vaccines in the context of preparing for future pandemics.

Nipah Virus-Another Threat From the World of Zoonotic Viruses

Among the diseases that pose a serious threat to public health, those caused by viruses are of great importance. The Nipah virus (NiV) belonging to the Paramyxoviridae family was reported in Malaysia in 1998/1999. Due to its high mortality in humans, its zoonotic nature, the possibility of human-to-human transmission, and the lack of an available vaccine, the World Health Organization (WHO) has recognized it as a global health problem. Depending on strain specificity, neurological symptoms and severe respiratory disorders are observed in NiV infection. In most confirmed cases of NiV epidemics, the appearance of the virus in humans was associated with the presence of various animal species, but generally, bats of Pteropus species are considered the most important natural animal NiV reservoir and vector. Consumption of contaminated food, contact with animals, and “human-to-human” direct contact were identified as NiV transmission routes. Due to the lack of vaccines and drugs with proven effectiveness against NiV, treatment of patients is limited to supportive and prophylactic.

Seasonal shedding patterns of diverse henipavirus-related paramyxoviruses in Egyptian rousette bats

Bat-borne viruses in the Henipavirus genus have been associated with zoonotic diseases of high morbidity and mortality in Asia and Australia. In Africa, the Egyptian rousette bat species (Rousettus aegyptiacus) is an important viral host in which Henipavirus-related viral sequences have previously been identified. We expanded these findings by assessing the viral dynamics in a southern African bat population. A longitudinal study of henipavirus diversity and excretion dynamics identified 18 putative viral species circulating in a local population, three with differing seasonal dynamics, and the winter and spring periods posing a higher risk of virus spillover and transmission. The annual peaks in virus excretion are most likely driven by subadults and may be linked to the waning of maternal immunity and recolonization of the roost in early spring. These results provide insightful information into the bat-host relationship that can be extrapolated to other populations across Africa and be communicated to at-risk communities as a part of evidence-based public health education and prevention measures against pathogen spillover threats.

Zoonotic Viruses and Conservation of Bats

Many of the recently emerging highly virulent zoonotic diseases have a likely bat origin, for example Hendra, Nipah, Ebola and diseases caused by coronaviruses. Presumably because of their long history of coevolution, most of these viruses remain subclinical in bats, but have the potential to cause severe illnesses in domestic and wildlife animals and also humans. Spillovers from bats to humans either happen directly (via contact with infected bats) or indirectly (via intermediate hosts such as domestic or wildlife animals, by consuming food items contaminated by saliva, faeces or urine of bats, or via other environmental sources). Increasing numbers of breakouts of zoonotic viral diseases among humans and livestock have mainly been accounted to human encroachment into natural habitat, as well as agricultural intensification, deforestation and bushmeat consumption. Persecution of bats, including the destruction of their roosts and culling of whole colonies, has led not only to declines of protected bat species, but also to an increase in virus prevalence in some of these populations. Educational efforts are needed in order to prevent future spillovers of bat-borne viruses to humans and livestock, and to further protect bats from unnecessary and counterproductive culling.