Nipah virus-associated encephalitis outbreak, Siliguri, India

Systematic mapping on the importance of vultures in the Indian public health discourse

Vultures are of immense ecological significance to forest and urban ecosystems. These birds play a major role in curbing environmental contamination through scavenging on carcasses. Prevention of spread of diseases is pivotal for public health and is an inexorable economic burden for any country. We present the crucial role vultures can play in disease mitigation and public health by regulating or decreasing the spread of zoonotic diseases. We elaborate examples from three zoonotic diseases; rabies, brucellosis and tuberculosis, which spread among dogs and cattle as well as human population. We establish the viable links in the transmission of these diseases from the infected dead and alive animals to humans and their possible exacerbation in the absence of vultures. These indirect links help formulate the case for increased interventions for disease spread and control along with conservation of these scavengers. Their role as natural and effective cleaners of the environment in the Indian health discourse is of importance because they can reduce the expenses of the government in waste management and maintenance of public health.

Architecture and antigenicity of the Nipah virus attachment glycoprotein

Nipah virus (NiV) and Hendra virus (HeV) are zoonotic henipaviruses (HNVs) responsible for outbreaks of encephalitis and respiratory illness. The entry of HNVs into host cells requires the attachment (G) and fusion (F) glycoproteins, which are the main targets of antibody responses. To understand viral infection and host immunity, we determined a cryo-electron microscopy structure of the NiV G homotetrameric ectodomain in complex with the nAH1.3 broadly neutralizing antibody Fab fragment. We show that a cocktail of two nonoverlapping G-specific antibodies neutralizes NiV and HeV synergistically and limits the emergence of escape mutants. Analysis of polyclonal serum antibody responses elicited by vaccination of macaques with NiV G indicates that the receptor binding head domain is immunodominant. These results pave the way for implementing multipronged therapeutic strategies against these deadly pathogens.

Defective Interfering Viral Particle Treatment Reduces Clinical Signs and Protects Hamsters from Lethal Nipah Virus Disease

Defective interfering particles (DIs) contain a considerably smaller genome than the parental virus but retain replication competency. As DIs can directly or indirectly alter propagation kinetics of the parental virus, they offer a novel approach to antiviral therapy, capitalizing on knowledge from natural infection. However, efforts to translate in vitro inhibition to in vivo screening models remain limited. We investigated the efficacy of virus-like particles containing DI genomes (therapeutic infectious particles [TIPs]) in the Syrian hamster model of lethal Nipah virus (NiV) disease. We found that coadministering a high dose of TIPs intraperitoneally with virus challenge improved clinical course and reduced lethality. To mimic natural exposure, we also evaluated lower-dose TIP delivery and virus challenge intranasally, finding equally efficacious reduction in disease severity and overall lethality. Eliminating TIP replicative capacity decreased efficacy, suggesting protection via direct inhibition. These data provide evidence that TIP-mediated treatment can confer protection against disease and lethal outcome in a robust animal NiV model, supporting further development of TIP treatment for NiV and other high-consequence pathogens. IMPORTANCE Here, we demonstrate that treatment with defective interfering particles (DIs), a natural by-product of viral infection, can significantly improve the clinical course and outcome of viral disease. When present with their parental virus, DIs can directly or indirectly alter viral propagation kinetics and exert potent inhibitory properties in cell culture. We evaluated the efficacy of a selection of virus-like particles containing DI genomes (TIPs) delivered intranasally in a lethal hamster model of Nipah virus disease. We demonstrate significantly improved clinical outcomes, including reduction in both lethality and the appearance of clinical signs. This work provides key efficacy data in a robust model of Nipah virus disease to support further development of TIP-mediated treatment against high-consequence viral pathogens.

Nipah Virus Mystery: Insight into Transmission and Mechanism of Disease Progression

Nipah virus (NiV) belongs to the biosafety level four (BSL-4) group of human pathogens of zoonotic origin. It is an emerging pathogen capable of causing a variety of clinical presentations, including encephalitis and severe acute respiratory illness, which can be fatal. Interestingly, it can also cause asymptomatic infections, which can relapse after a long period of time ranging from months to years following initial infection. Zoonotic transmission involves bats or pigs. In addition, transmission via contaminated food and occasional human to human direct transmission may also occur. It can have diverse epidemiological features and can have a very high case fatality ratio. Although a variety of immunological and molecular assays have been developed and epidemiological monitoring procedures for this disease have been introduced, there are no drugs available for this virus. Vaccines are at different stages of development. In this mini-review, we present the latest information on the Nipah virus; primarily focusing on emergence, transmission, pathogenic mechanisms and possible prophylactic and treatment options.

Nipah Virus Outbreak in Kerala State, India Amidst of COVID-19 Pandemic

We report here a Nipah virus (NiV) outbreak in Kozhikode district of Kerala state, India, which had caused fatal encephalitis in a 12-year-old boy and the outbreak response, which led to the successful containment of the disease and the related investigations. Quantitative real-time reverse transcription (RT)-PCR, ELISA-based antibody detection, and whole genome sequencing (WGS) were performed to confirm the NiV infection. Contacts of the index case were traced and isolated based on risk categorization. Bats from the areas near the epicenter of the outbreak were sampled for throat swabs, rectal swabs, and blood samples for NiV screening by real-time RT-PCR and anti-NiV bat immunoglobulin G (IgG) ELISA. A plaque reduction neutralization test was performed for the detection of neutralizing antibodies. Nipah viral RNA could be detected from blood, bronchial wash, endotracheal (ET) secretion, and cerebrospinal fluid (CSF) and anti-NiV immunoglobulin M (IgM) antibodies from the serum sample of the index case. Rapid establishment of an onsite NiV diagnostic facility and contact tracing helped in quick containment of the outbreak. NiV sequences retrieved from the clinical specimen of the index case formed a sub-cluster with the earlier reported Nipah I genotype sequences from India with more than 95% similarity. Anti-NiV IgG positivity could be detected in 21% of Pteropus medius (P. medius) and 37.73% of Rousettus leschenaultia (R. leschenaultia). Neutralizing antibodies against NiV could be detected in P. medius. Stringent surveillance and awareness campaigns need to be implemented in the area to reduce human-bat interactions and minimize spillover events, which can lead to sporadic outbreaks of NiV.

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.

Livestock and Risk Group 4 Pathogens: Researching Zoonotic Threats to Public Health and Agriculture in Maximum Containment

Maximum-containment laboratories are a unique and essential component of the bioeconomy of the United States. These facilities play a critical role in the national infrastructure, supporting research on a select set of especially dangerous pathogens, as well as novel, emerging diseases. Understanding the ecology, biology, and pathology at the human-animal interface of zoonotic spillover events is fundamental to efficient control and elimination of disease. The use of animals as human surrogate models or as target-host models in research is an integral part of unraveling the interrelated components involved in these dynamic systems. These models can prove vitally important in determining both viral- and host-factors associated with virus transmission, providing invaluable information that can be developed into better risk mitigation strategies. In this article, we focus on the use of livestock in maximum-containment, biosafety level-4 agriculture (BSL-4Ag) research involving zoonotic, risk group 4 pathogens and we provide an overview of historical associated research and contributions. Livestock are most commonly used as target-host models in high-consequence, maximum-containment research and are routinely used to establish data to assist in risk assessments. This article highlights the importance of animal use, insights gained, and how this type of research is essential for protecting animal health, food security, and the agriculture economy, as well as human public health in the face of emerging zoonotic pathogens. The utilization of animal models in high-consequence pathogen research and continued expansion to include available species of agricultural importance is essential to deciphering the ecology of emerging and re-emerging infectious diseases, as well as for emergency response and mitigation preparedness.

Nipah Virus: An Updated Review and Emerging Challenges

Many hospitals are teetering on the edge of being overwhelmed, with many already there because of the COVID-19 pandemic. Moreover, a recent report has also warned about the Nipah virus (NiV). NiV is a pleomorphic enveloped virus that belongs to the Paramyxoviridae family (genus Henipavirus); it affects both the respiratory and central nervous systems, with a fatality rate ranging from 40% to 75%, as documented by the World Health Organization. The first reported NiV outbreak was in early 1999 in Malaysia among people who contacted infected pigs. NiV also affected Bangladesh and India, where the main infection route was the consumption of raw date palm sap contaminated by bats. The World Health Organization has listed NiV as one of the emerging pathogens that can lead to severe outbreaks at any moment in the future with limited medical preparations and only a few projects in pharmaceutical firms. There is no licensed treatment for human use against NiV until now, and the management is limited to supportive care and symptomatic treatment. In severe cases with neurologic and respiratory complications, intensive care is needed. This article reviews the published literature and highlights the latest updates about this emerging pathogen and the methods to avoid the spread of this disease during this critical period.

Chimeric Fusion (F) and Attachment (G) Glycoprotein Antigen Delivery by mRNA as a Candidate Nipah Vaccine

Nipah virus (NiV) represents a significant pandemic threat with zoonotic transmission from bats-to-humans with almost annual regional outbreaks characterized by documented human-to-human transmission and high fatality rates. Currently, no vaccine against NiV has been approved. Structure-based design and protein engineering principles were applied to stabilize the fusion (F) protein in its prefusion trimeric conformation (pre-F) to improve expression and increase immunogenicity. We covalently linked the stabilized pre-F through trimerization domains at the C-terminus to three attachment protein (G) monomers, forming a chimeric design. These studies detailed here focus on mRNA delivery of NiV immunogens in mice, assessment of mRNA immunogen-specific design elements and their effects on humoral and cellular immunogenicity. The pre-F/G chimera elicited a strong neutralizing antibody response and a superior NiV-specific Tfh and other effector T cell response compared to G alone across both the mRNA and protein platforms. These findings enabled final candidate selection of pre-F/G Fd for clinical development.

Breakdown of a Nonlinear Stochastic Nipah Virus Epidemic Models through Efficient Numerical Methods

Background: Nipah virus (NiV) is a zoonotic virus (transmitted from animals to humans), which can also be transmitted through contaminated food or directly between people. According to a World Health Organization (WHO) report, the transmission of Nipah virus infection varies from animals to humans or humans to humans. The case fatality rate is estimated at 40% to 75%. The most infected regions include Cambodia, Ghana, Indonesia, Madagascar, the Philippines, and Thailand. The Nipah virus model is categorized into four parts: susceptible (S), exposed (E), infected (I), and recovered (R). Methods: The structural properties such as dynamical consistency, positivity, and boundedness are the considerable requirements of models in these fields. However, existing numerical methods like Euler-Maruyama and Stochastic Runge-Kutta fail to explain the main features of the biological problems. Results: The proposed stochastic non-standard finite difference (NSFD) employs standard and non-standard approaches in the numerical solution of the model, with positivity and boundedness as the characteristic determinants for efficiency and low-cost approximations. While the results from the existing standard stochastic methods converge conditionally or diverge in the long run, the solution by the stochastic NSFD method is stable and convergent over all time steps. Conclusions: The stochastic NSFD is an efficient, cost-effective method that accommodates all the desired feasible properties.

Recent advances in combating Nipah virus

Over the past 20 years, Nipah virus (NiV) has emerged as a significant, highly pathogenic bat-borne paramyxovirus causing severe respiratory disease and encephalitis in humans, and human-to-human transmission has been demonstrated in multiple outbreaks. In addition to causing serious illness in humans, NiV is a zoonotic pathogen capable of infecting a wide range of other mammalian species, including pigs and horses. While NiV has caused less than 700 human cases since its discovery in 1998/1999, the involvement of intermediate agricultural hosts can result in significant economic consequences. Owing to the severity of disease, capacity for human-to-human transmission, zoonotic potential, and lack of available approved therapeutic treatment options, NiV has been listed by the World Health Organization in their Blueprint list of priority pathogens as one of the eight most dangerous pathogens to monitor and prepare countermeasures to prevent a pandemic. Here, we discuss progress towards the development of therapeutic measures for the treatment of NiV infection and disease.

Assessing the feasibility of Nipah vaccine efficacy trials based on previous outbreaks in Bangladesh

BACKGROUND

Nipah virus (NiV) is an emerging, bat-borne pathogen that can be transmitted from person-to-person. Vaccines are currently being developed for NiV, and studies have been funded to evaluate their safety and immunogenicity. An important unanswered question is whether it will be possible to evaluate the efficacy of vaccine candidates in phase III clinical trials in a context where spillovers from the zoonotic reservoir are infrequent and associated with small outbreaks. The objective of this study was to investigate the feasibility of conducting a phase III vaccine trial in Bangladesh, the only country regularly reporting NiV cases.

METHODS

We used simulations based on previously observed NiV cases from Bangladesh, an assumed vaccine efficacy of 90% and other NiV vaccine target characteristics, to compare three vaccination study designs: (i) cluster randomized ring vaccination, (ii) cluster randomized mass vaccination, and (iii) an observational case-control study design.

RESULTS

The simulations showed that, assuming a ramp-up period of 10 days and a mean hospitalization delay of 4 days,a cluster-randomized ring vaccination trial would require 516 years and over 163,000 vaccine doses to run a ring vaccination trial under current epidemic conditions. A cluster-randomized mass vaccination trial in the two most affected districts would take 43 years and 1.83 million vaccine doses. An observational case-control design in these two districts would require seven years and 2.5 million vaccine doses.

DISCUSSION

Without a change in the epidemiology of NiV, ring vaccination or mass vaccination trials are unlikely to be completed within a reasonable time window. In this light, the remaining options are: (i) not conducting a phase III trial until the epidemiology of NiV changes, (ii) identifying alternative ways to licensure such as observational studies or controlled studies in animals such as in the US Food and Drug Administration's (FDA) Animal Rule.

Cooperativity mediated by rationally selected combinations of human monoclonal antibodies targeting the henipavirus receptor binding protein

Hendra virus and Nipah virus (NiV), members of the Henipavirus (HNV) genus, are zoonotic paramyxoviruses known to cause severe disease across six mammalian orders, including humans. We isolated a panel of human monoclonal antibodies (mAbs) from the B cells of an individual with prior exposure to equine Hendra virus (HeV) vaccine, targeting distinct antigenic sites. The most potent class of cross-reactive antibodies achieves neutralization by blocking viral attachment to the host cell receptors ephrin-B2 and ephrin-B3, with a second class being enhanced by receptor binding. mAbs from both classes display synergistic activity in vitro. In a stringent hamster model of NiV Bangladesh (NiV_B) infection, antibodies from both classes reduce morbidity and mortality and achieve synergistic protection in combination. These candidate mAbs might be suitable for use in a cocktail therapeutic approach to achieve synergistic potency and reduce the risk of virus escape.

Doyle et al. describe two human monoclonal antibodies that target the henipavirus receptor-binding protein, HENV-103 and HENV-117, that display highly potent activity in vitro and enhanced therapeutic efficacy in vivo when delivered as a cocktail.

A Comparative Study on the Effect Of Covid-19 And Spanish Flu In India – Lessons To Learn From The Past

The present era that we are living in is experiencing a globalcrisis due to a pandemic outbreak of COVID-19, whichhas affected millions around the world. The pandemic crisishas not only affected the physical forms of life but has alsobrought about a drastic change in the previously followedeconomic and social patterns. At present, there are somenorms that we are obliged to follow such as self-isolation,social distancing and restriction of several activities whichhas created a lot of confusion resulting in a huge hit on thesocioeconomic scenarios. The COVID-19 pandemic has notonly brought about fears in the life of the individuals buthas also created a panic due to which there has been an increasingdemand for medicine and consumable products asindividuals have resorted to stockpiling medical supplies andconsumer products, resulting in a huge socio-economic disparity‘with some getting all while the others get none.’. Theglobal scenarios and the symptoms of the COVID-19 havepaved a way for a comparison of the COVID-19 pandemicwith the Spanish flu pandemic of 1918. Several undertakingsare trying to implement strategies and successive methodsthat were learned in the past to restore normalcy in the socioeconomicconditions by providing individuals with variousforms of information to create awareness about COVID-19and to encourage the implementation of precautionarymethods for the same. This paper will help the readers tounderstand the similarities between the effects of COVID-19and the Spanish flu on India and will suggest the precautionarymeasures that must be taken to tackle the globalpandemically induced mishap.

A Brighton Collaboration standardized template with key considerations for a benefit/risk assessment for a soluble glycoprotein vaccine to prevent disease caused by Nipah or Hendra viruses

Auro Vaccines LLC has developed a protein vaccine to prevent disease from Nipah and Hendra virus infection that employs a recombinant soluble Hendra glycoprotein (HeV-sG) adjuvanted with aluminum phosphate. This vaccine is currently under clinical evaluation in a Phase 1 study. The Benefit-Risk Assessment of VAccines by TechnolOgy Working Group (BRAVATO; ex-V3SWG) has prepared a standardized template to describe the key considerations for the benefit-risk assessment of protein vaccines. This will help key stakeholders to assess potential safety issues and understand the benefit-risk of such a vaccine platform. The structured and standardized assessment provided by the template may also help contribute to improved public acceptance and communication of licensed protein vaccines.

Common Themes in Zoonotic Spillover and Disease Emergence: Lessons Learned from Bat- and Rodent-Borne RNA Viruses

Rodents (order Rodentia), followed by bats (order Chiroptera), comprise the largest percentage of living mammals on earth. Thus, it is not surprising that these two orders account for many of the reservoirs of the zoonotic RNA viruses discovered to date. The spillover of these viruses from wildlife to human do not typically result in pandemics but rather geographically confined outbreaks of human infection and disease. While limited geographically, these viruses cause thousands of cases of human disease each year. In this review, we focus on three questions regarding zoonotic viruses that originate in bats and rodents. First, what biological strategies have evolved that allow RNA viruses to reside in bats and rodents? Second, what are the environmental and ecological causes that drive viral spillover? Third, how does virus spillover occur from bats and rodents to humans?

Cospeciation of coronavirus and paramyxovirus with their bat hosts in the same geographical areas

Background

Bat-borne viruses are relatively host specific. We hypothesize that this host specificity is due to coevolution of the viruses with their hosts. To test this hypothesis, we investigated the coevolution of coronavirus and paramyxovirus with their bat hosts. Published nucleotide sequences of the RNA-dependent RNA polymerase (RdRp) gene of 60 coronavirus strains identified from 37 bat species, the RNA polymerase large (L) gene of 36 paramyxovirus strains from 29 bat species, and the cytochrome B (cytB) gene of 35 bat species were analyzed for coevolution signals. Each coevolution signal detected was tested and verified by global-fit cophylogenic analysis using software ParaFit, PACo, and eMPRess.

Results

Significant coevolution signals were detected in coronaviruses and paramyxoviruses and their bat hosts, and closely related bat hosts were found to carry closely related viruses.

Conclusions

Our results suggest that paramyxovirus and coronavirus coevolve with their hosts.

Vaccines to Emerging Viruses: Nipah and Hendra

Hendra virus (HeV) and Nipah virus (NiV) are bat-borne zoonotic para-myxoviruses identified in the mid- to late 1990s in outbreaks of severe disease in livestock and people in Australia and Malaysia, respectively. HeV repeatedly re-emerges in Australia while NiV continues to cause outbreaks in South Asia (Bangladesh and India), and these viruses have remained transboundary threats. In people and several mammalian species, HeV and NiV infections present as a severe systemic and often fatal neurologic and/or respiratory disease. NiV stands out as a potential pandemic threat because of its associated high case-fatality rates and capacity for human-to-human transmission. The development of effective vaccines, suitable for people and livestock, against HeV and NiV has been a research focus. Here, we review the progress made in NiV and HeV vaccine development, with an emphasis on those approaches that have been tested in established animal challenge models of NiV and HeV infection and disease.

Development of Molecular Diagnosis by PCR for the Detection of Infection and Gene Expression for Nipah Virus (NiV)

BACKGROUND AND OBJECTIVE

The epidemiology of Nipah virus (NiV) was shortly seen in many Asian countries like Malaysia, Bangladesh and India most recently. Nipah virus also synonym as bat born virus is transmitted primarily by fruit bats. The 2 different strains transmitted are Hendra (highly pathogenic) and Cedar (non-pathogenic). The present study was attempt to develop recombinant protein based reagents for molecular diagnosis of Nipah.

MATERIALS AND METHODS

The different primer sets were developed using bioinformatics software DNASTAR. The E. coli cells were used for recombinant protein expression.

RESULTS

The NiV 'G' region primers were designed and amplified for 1 kb fragment and cloned. The NiV 'G' fragments were sub-cloned in pET-28(+) B and pGEX-5x-1. Recombinant protein thus obtained in soluble form in both the cases was essayed using western blot. The result showed the protein expression yield was more in pET-28(+) B with low stability and vice versa for pGEX-5x-1.

CONCLUSION

The antibodies raised from the protein can be used as diagnostic reagent for detection of NiV. Thus, a new diagnostic technique can be industrialized.

CryoEM structure of the Nipah virus nucleocapsid assembly

Nipah and its close relative Hendra are highly pathogenic zoonotic viruses, storing their ssRNA genome in a helical nucleocapsid assembly formed by the N protein, a major viral immunogen. Here, we report the first cryoEM structure for a Henipavirus RNA-bound nucleocapsid assembly, at 3.5 Å resolution. The helical assembly is stabilised by previously undefined N- and C-terminal segments, contributing to subunit-subunit interactions. RNA is wrapped around the nucleocapsid protein assembly with a periodicity of six nucleotides per protomer, in the “3-bases-in, 3-bases-out” conformation, with protein plasticity enabling non-sequence specific interactions. The structure reveals commonalities in RNA binding pockets and in the conformation of bound RNA, not only with members of the Paramyxoviridae family, but also with the evolutionarily distant Filoviridae Ebola virus. Significant structural differences with other Paramyxoviridae members are also observed, particularly in the position and length of the exposed α-helix, residues 123–139, which may serve as a valuable epitope for surveillance and diagnostics.

Nipah virus is a highly pathogenic RNA virus which, along with the closely related Hendra virus, emerged relatively recently. Due to ~40% mortality rate and evidence of animal-to-human as well as human-to-human transmission, development of antivirals against the Nipah and henipaviral disease is particularly urgent. In common with other single-stranded RNA viruses, including Ebola and coronaviruses, the nucleocapsid assembly of the Nipah virus safeguards the viral genome, protecting it from degradation and facilitating its encapsidation and storage inside the virion. Here, we used cryo-electron microscopy to determine accurate three-dimensional structure for several different assemblies of the Nipah virus nucleocapsid protein, in particular a detailed structure for the complex of this protein with RNA. This structural information is important for understanding detailed molecular interactions driving and stabilizing the nucleocapsid assembly formation that are of fundamental importance for understanding similar processes in a large group of ssRNA viruses. Apart from highlighting structural similarities and differences with nucleocapsid proteins of other viruses of the Paramyxoviridae family, these data will inform the development of new antiviral approaches for the henipaviruses.

Two decades of one health surveillance of Nipah virus in Thailand

BACKGROUND

Nipah virus (NiV) infection causes encephalitis and has > 75% mortality rate, making it a WHO priority pathogen due to its pandemic potential. There have been NiV outbreak(s) in Malaysia, India, Bangladesh, and southern Philippines. NiV naturally circulates among fruit bats of the genus Pteropus and has been detected widely across Southeast and South Asia. Both Malaysian and Bangladeshi NiV strains have been found in fruit bats in Thailand. This study summarizes 20 years of pre-emptive One Health surveillance of NiV in Thailand, including triangulated surveillance of bats, and humans and pigs in the vicinity of roosts inhabited by NiV-infected bats.

METHODS

Samples were collected periodically and tested for NiV from bats, pigs and healthy human volunteers from Wat Luang village, Chonburi province, home to the biggest P. lylei roosts in Thailand, and other provinces since 2001. Archived cerebrospinal fluid specimens from encephalitis patients between 2001 and 2012 were also tested for NiV. NiV RNA was detected using nested reverse transcription polymerase chain reaction (RT-PCR). NiV antibodies were detected using enzyme-linked immunosorbent assay or multiplex microsphere immunoassay.

RESULTS

NiV RNA (mainly Bangladesh strain) was detected every year in fruit bats by RT-PCR from 2002 to 2020. The whole genome sequence of NiV directly sequenced from bat urine in 2017 shared 99.17% identity to NiV from a Bangladeshi patient in 2004. No NiV-specific IgG antibodies or RNA have been found in healthy volunteers, encephalitis patients, or pigs to date. During the sample collection trips, 100 community members were trained on how to live safely with bats.

CONCLUSIONS

High identity shared between the NiV genome from Thai bats and the Bangladeshi patient highlights the outbreak potential of NiV in Thailand. Results from NiV cross-sectoral surveillance were conveyed to national authorities and villagers which led to preventive control measures, increased surveillance of pigs and humans in vicinity of known NiV-infected roosts, and increased vigilance and reduced risk behaviors at the community level. This proactive One Health approach to NiV surveillance is a success story; that increased collaboration between the human, animal, and wildlife sectors is imperative to staying ahead of a zoonotic disease outbreak.

Outbreak prone communicable diseases of public health importance in the northern districts of West Bengal - Current status & the way forward

India is perilously poised on the threshold of an explosion of infectious diseases, some of which have witnessed re-emergence while others await apposite opportunity to do so. The State of West Bengal is uniquely positioned with its innate geographical vulnerabilities that favour outbreaks of a host of infectious diseases. The northern districts of this State are well known endemic areas for many outbreak prone communicable diseases like malaria, Japanese encephalitis, scrub typhus, dengue and kala-azar. An outbreak of Nipah virus in the recent past is a pointer towards the emerging and re-emerging threat in these regions and warrants urgent prioritization for surveillance and monitoring of these diseases. Identification of risk factors, challenges in delivery of primary healthcare, implementation of intervention strategies along with strengthening of healthcare setup are also the need of the hour. Multisectoral initiatives with emphasis on understanding the complex and rapidly evolving human-animal-vector dynamics as envisaged under the ‘One Health’ concept are indubitably important pillars in the effective management of these emerging public health challenges.

Nipah Virus Efficiently Replicates in Human Smooth Muscle Cells without Cytopathic Effect

Nipah virus (NiV) is a highly pathogenic zoonotic virus with a broad species tropism, originating in pteropid bats. Human outbreaks of NiV disease occur almost annually, often with high case-fatality rates. The specific events that lead to pathogenesis are not well defined, but the disease has both respiratory and encephalitic components, with relapsing encephalitis occurring in some cases more than a year after initial infection. Several cell types are targets of NiV, dictated by the expression of the ephrin-B2/3 ligand on the cell's outer membrane, which interact with the NiV surface proteins. Vascular endothelial cells (ECs) are major targets of infection. Cytopathic effects (CPE), characterized by syncytia formation and cell death, and an ensuing vasculitis, are a major feature of the disease. Smooth muscle cells (SMCs) of the tunica media that line small blood vessels are infected in humans and animal models of NiV disease, although pathology or histologic changes associated with antigen-positive SMCs have not been reported. To gain an understanding of the possible contributions that SMCs might have in the development of NiV disease, we investigated the susceptibility and potential cytopathogenic changes of human SMCs to NiV infection in vitro. SMCs were permissive for NiV infection and resulted in high titers and prolonged NiV production, despite a lack of cytopathogenicity, and in the absence of detectable ephrin-B2/3. These results indicate that SMC might be important contributors to disease by producing progeny NiV during an infection, without suffering cytopathogenic consequences.

Potent Henipavirus Neutralization by Antibodies Recognizing Diverse Sites on Hendra and Nipah Virus Receptor Binding Protein

Hendra (HeV) and Nipah (NiV) viruses are emerging zoonotic pathogens in the Henipavirus genus causing outbreaks of disease with very high case fatality rates. Here, we report the first naturally occurring human monoclonal antibodies (mAbs) against HeV receptor binding protein (RBP). All isolated mAbs neutralized HeV, and some also neutralized NiV. Epitope binning experiments identified five major antigenic sites on HeV-RBP. Animal studies demonstrated that the most potent cross-reactive neutralizing mAbs, HENV-26 and HENV-32, protected ferrets in lethal models of infection with NiV Bangladesh 3 days after exposure. We solved the crystal structures of mAb HENV-26 in complex with both HeV-RBP and NiV-RBP and of mAb HENV-32 in complex with HeV-RBP. The studies reveal diverse sites of vulnerability on RBP recognized by potent human mAbs that inhibit virus by multiple mechanisms. These studies identify promising prophylactic antibodies and define protective epitopes that can be used in rational vaccine design.

Anticipation of Antigenic Sites for the Goal of Vaccine Designing Against Nipah Virus: An Immunoinformatics Inquisitive Quest

With time, the Nipah virus has been proved as a fatal and dangerous pathogen for humanity. Nipah virus has its origin from bats and severely affects the respiratory as well as neurological organs. Regular outbreaks and unavailability of proper treatment for Nipah virus infection, demands the designing of vaccine for this disease. This prediction study was conducted to explore B cell epitopes from the Nipah virus’s proteome using the immunoinformatics approach. In this curious quest of anticipation of antigenic sites for the Insilico peptide vaccine for the Nipah virus, nine NV-B strain proteins were retrieved for further series of investigations. After sequential refining through immunoinformatics approaches, a total of 26 epitopes was selected to perform molecular modeling and docking. PEPstrMOD and Swiss model, respectively performed 3D modeling of epitopes with their respective alleles. Based on minimum binding energy, four epitopes viz. LHLGNFVRR, LNLSPLIQR, YHNMSPINR and FRRNNAIAF were predicted as promiscuous B cell epitopes. Based on low binding affinity and high population coverage worldwide, epitope LHLGNFVRR was finally selected. Increased Stability of the LHLGNFVRR- HLA DRB_1301 complex during simulation studies exhibit it as the most promising vaccine bidder. So complex of LHLGNFVRR- HLA DRB_1301 has shown most significance result for vaccine and for further validation and confirmation, wet lab and clinical trials can provide the potential of predicted peptides for the subunit vaccine.

Clinical Manifestations of Nipah Virus-Infected Patients Who Presented to the Emergency Department During an Outbreak in Kerala State in India, May 2018

BACKGROUND

An outbreak of Nipah virus (NiV) disease occurred in the Kozhikode district of Kerala State in India in May 2018. Several cases were treated at the emergency medicine department (ED) of the Government Medical College, Kozhikode (GMCK). The clinical manifestations and outcome of these cases are described.

METHODS

The study included 12 cases treated in the ED of GMCK. Detailed clinical examination, laboratory investigations, and molecular testing for etiological diagnosis were performed.

RESULTS

The median age of the patients was 30 years and the male to female ratio was 1.4:1.0. All the cases except the index case contracted the infection from hospitals. The median incubation period was 10 days, and the case fatality ratio was 83.3%. Ten (83.3%) patients had encephalitis and 9 out of 11 patients whose chest X-rays were obtained had bilateral infiltrates. Three patients had bradycardia and intractable hypotension requiring inotropes. Encephalitis, acute respiratory distress syndrome, and myocarditis were the clinical prototypes, but there were large overlaps between these. Ribavirin therapy was given to a subset of the patients. Although there was a 20% reduction in NiV encephalitis cases treated with the drug, the difference was not statistically significant. The outbreak ended soon after the introduction of total isolation of patients and barrier nursing.

CONCLUSION

The outbreak of NiV disease in Kozhikode in May 2018 presented as encephalitis, acute respiratory distress and myocarditis or combinations of these. The CFR was high. Ribavirin therapy was tried but no evidence for its benefit could be obtained.

Evolution of Nipah Virus Infection: Past, Present, and Future Considerations

Nipah virus (NiV) is a zoonotic paramyxovirus of the Henipavirus genus first identified in Malaysia in 1998. Henipaviruses have bat reservoir hosts and have been isolated from fruit bats found across Oceania, Asia, and Africa. Bat-to-human transmission is thought to be the primary mode of human NiV infection, although multiple intermediate hosts are described. Human infections with NiV were originally described as a syndrome of fever and rapid neurological decline following contact with swine. More recent outbreaks describe a syndrome with prominent respiratory symptoms and human-to-human transmission. Nearly annual outbreaks have been described since 1998 with case fatality rates reaching greater than 90%. The ubiquitous nature of the reservoir host, increasing deforestation, multiple mode of transmission, high case fatality rate, and lack of effective therapy or vaccines make NiV’s pandemic potential increasingly significant. Here we review the epidemiology and microbiology of NiV as well as the therapeutic agents and vaccines in development.

Detection of Nipah virus in Pteropus medius in 2019 outbreak from Ernakulam district, Kerala, India

Background

In June 2019, Nipah virus (NiV) infection was detected in a 21-year-old male (index case) of Ernakulum, Kerala, India. This study was undertaken to determine if NiV was in circulation in Pteropus species (spp) in those areas where the index case had visit history in 1 month.

Methods

Specialized techniques were used to trap the Pteropus medius bats (random sampling) in the vicinity of the index case area. Throat and rectal swabs samples of 141 bats along with visceral organs of 92 bats were collected to detect the presence of NiV by real-time reverse transcriptase-polymerase chain reaction (qRTPCR). Serum samples of 52 bats were tested for anti-NiV Immunoglobulin (Ig) G antibodies by Enzyme-Linked Immunosorbent Assay (ELISA). The complete genome of NiV was sequenced by next-generation sequencing (NGS) from the tissues and swab samples of bats.

Results

One rectal swab sample and three bats visceral organs were found positive for the NiV. Interestingly, 20.68% (12/58) of Pteropus were positive for anti-NiV IgG antibodies. NiV sequences of 18,172; 17,200 and 15,100 nucleotide bps could be retrieved from three Pteropus bats.

Conclusion

A distinct cluster of NiV sequences, with significant net-evolutionary nucleotide divergence, was obtained, suggesting the circulation of new genotype (I-India) in South India. NiV Positivity in Pteropus spp. of bats revealed that NiV is circulating in many districts of Kerala state, and active surveillance of NiV should be immediately set up to know the hotspot area for NiV infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-05865-7.

The Ecology of Nipah Virus in Bangladesh: A Nexus of Land-Use Change and Opportunistic Feeding Behavior in Bats

Nipah virus is a bat-borne paramyxovirus that produces yearly outbreaks of fatal encephalitis in Bangladesh. Understanding the ecological conditions that lead to spillover from bats to humans can assist in designing effective interventions. To investigate the current and historical processes that drive Nipah spillover in Bangladesh, we analyzed the relationship among spillover events and climatic conditions, the spatial distribution and size of Pteropus medius roosts, and patterns of land-use change in Bangladesh over the last 300 years. We found that 53% of annual variation in winter spillovers is explained by winter temperature, which may affect bat behavior, physiology, and human risk behaviors. We infer from changes in forest cover that a progressive shift in bat roosting behavior occurred over hundreds of years, producing the current system where a majority of P. medius populations are small (median of 150 bats), occupy roost sites for 10 years or more, live in areas of high human population density, and opportunistically feed on cultivated food resources-conditions that promote viral spillover. Without interventions, continuing anthropogenic pressure on bat populations similar to what has occurred in Bangladesh could result in more regular spillovers of other bat viruses, including Hendra and Ebola viruses.

Viral Zoonoses of National Importance in Ghana: Advancements and Opportunities for Enhancing Capacities for Early Detection and Response

Zoonotic diseases have devastating impacts on human and animal health, livelihoods, and economies. Addressing the complex web of interrelated factors leading to zoonotic disease emergence and spread requires a transdisciplinary, cross-sectoral approach, One Health. The One Health approach, which considers the linkages between the health of people, animals, and their shared environment, presents opportunities to reduce these impacts through a more holistic coordinated strategy to understanding and mitigating disease risks. Understanding the linkages between animal, human, and environmental health risks and outcomes is critical for developing early detection systems and risk reduction strategies to address known and novel zoonotic disease threats. Nearly 70 countries across the world, including Ghana, have signed on to the Global Health Security Agenda (GHSA), which is facilitating multisectoral approaches to strengthen country capacities in the prevention and early detection of and respond to infectious disease threats. Currently, Ghana has not yet formalized a national One Health policy. The lack of a clearly defined multisectoral platform and limited collaboration among key Ghanaian Ministries, Departments, and Agencies has impacted the country's ability to effectively mitigate and respond to emerging and reemerging zoonoses. Many of these emerging zoonoses are caused by viruses, which, because of their diversity and evolutionary properties, are perceived to pose the greatest threat to global health security. Here, we review viral zoonoses of national importance and priority in Ghana, highlight recent advancements in One Health capacities, and discuss opportunities for implementing One Health approaches to mitigate zoonotic disease threats.

Inference of Nipah virus evolution, 1999-2015

Despite near-annual human outbreaks of Nipah virus (NiV) disease in Bangladesh, typically due to individual spillover events from the local bat population, only twenty whole-genome NiV sequences exist from humans and ten from bats. NiV whole-genome sequences from annual outbreaks have been challenging to generate, primarily due to the low viral load in human throat swab and serum specimens. Here, we used targeted enrichment with custom NiV-specific probes and generated thirty-five additional unique full-length genomic sequences directly from human specimens and viral isolates. We inferred the temporal and geographic evolutionary history of NiV in Bangladesh and expanded a tool to visualize NiV spatio-temporal spread from a Bayesian continuous diffusion analysis. We observed that strains from Bangladesh segregated into two distinct clades that have intermingled geographically in Bangladesh over time and space. As these clades expanded geographically and temporally, we did not observe evidence for significant branch and site-specific selection, except for a single site in the Henipavirus L polymerase. However, the Bangladesh 1 and 2 clades are differentiated by mutations initially occurring in the polymerase, with additional mutations accumulating in the N, G, F, P, and L genes on external branches. Modeling the historic geographical and temporal spread demonstrates that while widespread, NiV does not exhibit significant genetic variation in Bangladesh. Thus, future public health measures should address whether NiV within in the bat population also exhibits comparable genetic variation, if zoonotic transmission results in a genetic bottleneck and if surveillance techniques are detecting only a subset of NiV.

A Review on Emerging Infectious Diseases Prioritized Under the 2018 WHO Research and Development Blueprint: Lessons from the Indian Context

Objective: This review describes the current scenario of a priority group of emerging infectious diseases (EIDs) listed by World Health Organization (WHO), and their main determinants and drivers for the emergence/spread of the diseases. The gaps and strategies developed by India to meet the WHO guidelines on the effective control of epidemic-prone diseases and outbreaks are also presented in the review. Methods: Epidemiologic information of EIDs, namely Crimean-Congo hemorrhagic fever (CCHF), Ebola and Marburg viruses (EboV and MarV), Zika virus (ZIKAV), Rift Valley fever (RVF), Middle East respiratory syndrome, severe acute respiratory syndrome (SARS), Nipah and Hendra virus (NiV and HeV), and Lassa fever virus (LASV), was drawn from international and national electronic databases to assess the situation. A brief view on the novel coronavirus disease 2019 (COVID-19) in India is also included. Results: There are no reports for human infection of EboV, MarV, RVF, and LASV in India. CCHF, SARS, ZIKAV, and NiV have been involved in outbreaks in eight states of India, while COVID-19 is currently reported from majority of states. India has deeply strengthened its surveillance and response system of outbreaks and epidemic-prone diseases. Conclusions: Despite its enormous improvements made in the anticipation of such threats, still more efforts are needed in sensitization of populations as well as hospital management in the context to EIDs, as addressed in the review. Furthermore, there is still a need for more research and development activities to efficiently control EIDs.

Nipah virus dynamics in bats and implications for spillover to humans

Nipah virus (NiV) is an emerging bat-borne zoonotic virus that causes near-annual outbreaks of fatal encephalitis in South Asia-one of the most populous regions on Earth. In Bangladesh, infection occurs when people drink date-palm sap contaminated with bat excreta. Outbreaks are sporadic, and the influence of viral dynamics in bats on their temporal and spatial distribution is poorly understood. We analyzed data on host ecology, molecular epidemiology, serological dynamics, and viral genetics to characterize spatiotemporal patterns of NiV dynamics in its wildlife reservoir, Pteropus medius bats, in Bangladesh. We found that NiV transmission occurred throughout the country and throughout the year. Model results indicated that local transmission dynamics were modulated by density-dependent transmission, acquired immunity that is lost over time, and recrudescence. Increased transmission followed multiyear periods of declining seroprevalence due to bat-population turnover and individual loss of humoral immunity. Individual bats had smaller host ranges than other Pteropus species (spp.), although movement data and the discovery of a Malaysia-clade NiV strain in eastern Bangladesh suggest connectivity with bats east of Bangladesh. These data suggest that discrete multiannual local epizootics in bat populations contribute to the sporadic nature of NiV outbreaks in South Asia. At the same time, the broad spatial and temporal extent of NiV transmission, including the recent outbreak in Kerala, India, highlights the continued risk of spillover to humans wherever they may interact with pteropid bats and the importance of limiting opportunities for spillover throughout Pteropus's range.

Genetic diversity of Nipah virus in Bangladesh

BACKGROUND

Nipah virus (NiV) infection, often fatal in humans, is primarily transmitted in Bangladesh through the consumption of date palm sap contaminated by Pteropus bats. Person-to-person transmission is also common and increases the concern of large outbreaks. This study aimed to characterize the molecular epidemiology, phylogenetic relationship, and the evolution of the nucleocapsid gene (N gene) of NiV.

METHODS

We conducted molecular detection, genetic characterization, and Bayesian time-scale evolution analyses of NiV using pooled Pteropid bat roost urine samples from an outbreak area in 2012 and archived RNA samples from NiV case patients identified during 2012-2018 in Bangladesh.

RESULTS

NiV-RNA was detected in 19% (38/456) of bat roost urine samples and among them; nine N gene sequences were recovered. We also retrieved sequences from 53% (21 out of 39) of archived RNA samples from patients. Phylogenetic analysis revealed that all Bangladeshi strains belonged to NiV-BD genotype and had an evolutionary rate of 4.64 × 10^-4 substitutions/site/year. The analyses suggested that the strains of NiV-BD genotype diverged during 1995 and formed two sublineages.

CONCLUSION

This analysis provides further evidence that the NiV strains of the Malaysian and Bangladesh genotypes diverged recently and continue to evolve. More extensive surveillance of NiV in bats and human will be helpful to explore strain diversity and virulence potential to infect humans through direct or person-to-person virus transmission.

Prediction of the binding interface between monoclonal antibody m102.4 and Nipah attachment glycoprotein using structure-guided alanine scanning and computational docking

Nipah Virus (NiV) has been designated as a priority disease with an urgent need for therapeutic development by World Health Organization. The monoclonal antibody m102.4 binds to the immunodominant NiV receptor-binding glycoprotein (GP), and potently neutralizes NiV, indicating its potential as a therapeutic agent. Although the co-crystal structure of m102.3, an m102.4 derivative, in complex with the GP of the related Hendra Virus (HeV) has been solved, the structural interaction between m102.4 and NiV is uncharacterized. Herein, we used structure-guided alanine-scanning mutagenesis to map the functional epitope and paratope residues that govern the antigen-antibody interaction. Our results revealed that the binding of m102.4 is mediated predominantly by two residues in the HCDR3 region, which is unusually small for an antibody-antigen interaction. We performed computational docking to generate a structural model of m102.4-NiV interaction. Our model indicates that m102.4 targets the common hydrophobic central cavity and a hydrophilic rim on the GP, as observed for the m102.3-HeV co-crystal, albeit with Fv orientation differences. In summary, our study provides insight into the m102.4-NiV interaction, demonstrating that structure-guided alanine-scanning and computational modeling can serve as the starting point for additional antibody reengineering (e.g. affinity maturation) to generate potential therapeutic candidates.

SARS-CoV-2 and COVID-19: A genetic, epidemiological, and evolutionary perspective

In less than five months, COVID-19 has spread from a small focus in Wuhan, China, to more than 5 million people in almost every country in the world, dominating the concern of most governments and public health systems. The social and political distresses caused by this epidemic will certainly impact our world for a long time to come. Here, we synthesize lessons from a range of scientific perspectives rooted in epidemiology, virology, genetics, ecology and evolutionary biology so as to provide perspective on how this pandemic started, how it is developing, and how best we can stop it.

Adaptive Immune Responses in Humans During Nipah Virus Acute and Convalescent Phases of Infection

BACKGROUND

Nipah virus (NiV) is 1 of 10 potential causes of imminent public health emergencies of international concern. We investigated the NiV outbreak that occurred in May 2018 in Kerala, India. Here we describe the longitudinal characteristics of cell-mediated and humoral immune responses to NiV infection during the acute and convalescent phases in 2 human survivors.

METHODS

Serial blood samples were obtained from the only 2 survivors of the NiV outbreak in Kerala. We used flow cytometry to determine the absolute T-lymphocyte and B-lymphocyte counts and the phenotypes of both T and B cells. We also detected and quantitated the humoral immune response to NiV by virus-specific immunoglobulin M (IgM) and immunoglobulin G (IgG) enzyme-linked immunosorbent assay.

RESULTS

Absolute numbers of T lymphocytes remained within normal limits throughout the period of illness studied in both survivors. However, a marked elevation of activated CD8 T cells was observed in both cases. More than 30% of total CD8 T cells expressed Ki67, indicating active proliferation. Proliferating (Ki-67+) CD8 T cells expressed high levels of granzyme B and PD-1, consistent with the profile of acute effector cells. Total B-lymphocyte, activated B-cell, and plasmablast counts were also elevated in NiV survivors. These individuals developed detectable NiV-specific IgM and IgG antibodies within a week of disease onset. Clearance of NiV RNA from blood preceded the appearance of virus-specific IgG and coincided with the peak of activated CD8 T cells.

CONCLUSIONS

We describe for the first time longitudinal kinetic data on the activation status of human B- and T-cell populations during acute NiV infection. While marked CD8 T-cell activation was observed with effector characteristics, activated CD4 T cells were less prominent.

Ebola, COVID-19, and emerging infectious disease: lessons learned and future preparedness

PURPOSE OF REVIEW

To highlight the lessons learned from the Ebola outbreak that may inform our approach to the COVID-19 pandemic, particularly related to the widespread disruption of healthcare, ophthalmic disease manifestations, and vision health systems strengthening for future outbreaks.

RECENT FINDINGS

Coronavirus disease 2019 (COVID-19), first detected in China in December 2019, has become a worldwide health emergency, with significant disruption of all aspects of society, including travel, business, and medical care. Although this pandemic has had unprecedented effects on healthcare delivery in the United States, experiences from recent Ebola virus disease (EVD) outbreaks in Africa provide insight and inform our approach to COVID-19 and outbreak preparedness. Like COVID-19, the rapid emergence of Ebola required new clinical and surgical approaches to understand its associated spectrum of ophthalmic complications and the potential for Ebola viral persistence within the eye and in tear film. Recent reports of ophthalmic findings associated with COVID-19 include conjunctivitis, retinopathy, and molecular evidence of virus within the tear film in a minority of cases. Yet, more rigorous approaches to understand ophthalmic disease and transmission risk associated with COVID-19 are needed. Gaps also remain in our understanding of eye disease associated with other high priority emerging infectious diseases including Nipah, Lassa fever, Marburg virus, and others.

SUMMARY

Thoroughly understanding the ophthalmic findings and transmission risk associated with COVID-19 is paramount during this pandemic, providing additional measures of safety while resuming ophthalmic care for all patients. Vision health systems preparedness measures developed during recent EVD outbreaks and the current pandemic provide models for ophthalmic clinical practice, research, and education, as we continue to address COVID-19 and future emerging infectious disease threats.

A 'what-if' scenario: Nipah virus attacks pig trade chains in Thailand

Background

Nipah virus (NiV) is a fatal zoonotic agent that was first identified amongst pig farmers in Malaysia in 1998, in an outbreak that resulted in 105 fatal human cases. That epidemic arose from a chain of infection, initiating from bats to pigs, and which then spilled over from pigs to humans. In Thailand, bat-pig-human communities can be observed across the country, particularly in the central plain. The present study therefore aimed to identify high-risk areas for potential NiV outbreaks and to model how the virus is likely to spread. Multi-criteria decision analysis (MCDA) and weighted linear combination (WLC) were employed to produce the NiV risk map. The map was then overlaid with the nationwide pig movement network to identify the index subdistricts in which NiV may emerge. Subsequently, susceptible-exposed-infectious-removed (SEIR) modeling was used to simulate NiV spread within each subdistrict, and network modeling was used to illustrate how the virus disperses across subdistricts.

Results

Based on the MCDA and pig movement data, 14 index subdistricts with a high-risk of NiV emergence were identified. We found in our infectious network modeling that the infected subdistricts clustered in, or close to the central plain, within a range of 171 km from the source subdistricts. However, the virus may travel as far as 528.5 km (R₀ = 5).

Conclusions

In conclusion, the risk of NiV dissemination through pig movement networks in Thailand is low but not negligible. The risk areas identified in our study can help the veterinary authority to allocate financial and human resources to where preventive strategies, such as pig farm regionalization, are required and to contain outbreaks in a timely fashion once they occur.

The critical region for viral RNA encapsidation in leader promoter of Nipah virus

Encapsidation by nucleocapsid (N) protein is crucial for viral RNA to serve as a functional template for virus replication. However, the potential region that is vital for RNA encapsidation of Nipah virus (NiV) is still unknown. Thus, this study was aimed to identify these regions using a NiV minireplicon system. A series of broad range internal deletion mutations was generated in the 5' non-translated region (NTR) of the N gene mRNA region of NiV leader promoter via site-directed overlapping PCR-mediated mutagenesis. The mutation effects on synthesis and encapsidation of antigenome RNA, transcription, and RNA binding affinity of N protein were evaluated. The deletions of nucleotides 73-108, 79-108, and 85-108 from NiV leader promoter inhibited the encapsidation of antigenome RNA, while the deletion of nucleotides 103-108 suppressed the synthesis and encapsidation of antigenome RNA, implying that these regions are required for genome replication. Surprisingly, none of the mutations had detrimental effect on viral transcription. Using isothermal titration calorimetry, the binding of NiV N protein to genome or antigenome RNA transcript lacking of nucleotides 73-108 was found to be suppressed. Additionally, in silico analysis on secondary structure of genome RNA further supported the plausible cause of inefficient encapsidation of antigenome RNA by the loss of encapsidation signal in genome template. In conclusion, this study suggests that the nucleotides 73-90 within 5' NTR of the N gene mRNA region in NiV leader promoter contain cis-acting RNA element that is important for efficient encapsidation of antigenome RNA.

Structure-Based Design of Nipah Virus Vaccines: A Generalizable Approach to Paramyxovirus Immunogen Development

Licensed vaccines or therapeutics are rarely available for pathogens with epidemic or pandemic potential. Developing interventions for specific pathogens and defining generalizable approaches for related pathogens is a global priority and inherent to the UN Sustainable Development Goals. Nipah virus (NiV) poses a significant epidemic threat, and zoonotic transmission from bats-to-humans with high fatality rates occurs almost annually. Human-to-human transmission of NiV has been documented in recent outbreaks leading public health officials and government agencies to declare an urgent need for effective vaccines and therapeutics. Here, we evaluate NiV vaccine antigen design options including the fusion glycoprotein (F) and the major attachment glycoprotein (G). A stabilized prefusion F (pre-F), multimeric G constructs, and chimeric proteins containing both pre-F and G were developed as protein subunit candidate vaccines. The proteins were evaluated for antigenicity and structural integrity using kinetic binding assays, electron microscopy, and other biophysical properties. Immunogenicity of the vaccine antigens was evaluated in mice. The stabilized pre-F trimer and hexameric G immunogens both induced serum neutralizing activity in mice, while the post-F trimer immunogen did not elicit neutralizing activity. The pre-F trimer covalently linked to three G monomers (pre-F/G) induced potent neutralizing antibody activity, elicited responses to the greatest diversity of antigenic sites, and is the lead candidate for clinical development. The specific stabilizing mutations and immunogen designs utilized for NiV were successfully applied to other henipaviruses, supporting the concept of identifying generalizable solutions for prototype pathogens as an approach to pandemic preparedness.

The Use of Large-Particle Aerosol Exposure to Nipah Virus to Mimic Human Neurological Disease Manifestations in the African Green Monkey

Nipah virus (NiV) is an emerging virus associated with outbreaks of acute respiratory disease and encephalitis. To develop a neurological model for NiV infection, we exposed 6 adult African green monkeys to a large-particle (approximately 12 μm) aerosol containing NiV (Malaysian isolate). Brain magnetic resonance images were obtained at baseline, every 3 days after exposure for 2 weeks, and then weekly until week 8 after exposure. Four of six animals showed abnormalities reminiscent of human disease in brain magnetic resonance images. Abnormalities ranged from cytotoxic edema to vasogenic edema. The majority of lesions were small infarcts, and a few showed inflammatory or encephalitic changes. Resolution or decreased size in some lesions resembled findings reported in patients with NiV infection. Histological lesions in the brain included multifocal areas of encephalomalacia, corresponding to known ischemic foci. In other regions of the brain there was evidence of vasculitis, with perivascular infiltrates of inflammatory cells and rare intravascular fibrin thrombi. This animal model will help us better understand the acute neurological features of NiV infection and develop therapeutic approaches for managing disease caused by NiV infection.

Inhibition of Nipah Virus by Defective Interfering Particles

The error-prone nature of RNA-dependent RNA polymerases drives the diversity of RNA virus populations. Arising within this diversity is a subset of defective viral genomes that retain replication competency, termed defective interfering (DI) genomes. These defects are caused by aberrant viral polymerase reinitiation on the same viral RNA template (deletion DI species) or the nascent RNA strand (copyback DI species). DI genomes have previously been shown to alter the dynamics of a viral population by interfering with normal virus replication and/or by stimulating the innate immune response. In this study, we investigated the ability of artificially produced DI genomes to inhibit Nipah virus (NiV), a highly pathogenic biosafety level 4 paramyxovirus. High multiplicity of infection passaging of both NiV clinical isolates and recombinant NiV in Vero cells generated an extensive DI population from which individual DIs were identified using next-generation sequencing techniques. Assays were established to generate and purify both naturally occurring and in silico-designed DIs as fully encapsidated, infectious virus-like particles termed defective interfering particles (DIPs). We demonstrate that several of these NiV DIP candidates reduced NiV titers by up to 4 logs in vitro. These data represent a proof-of-principle that a therapeutic application of DIPs to combat NiV infections may be an alternative source of antiviral control for this disease.