If it becomes more efficient in spreading, this could be a big issue because then you have a virus that efficiently jumps from humans to humans as through the air, which means it's hard to stop. In addition to that, this virus is super deadly and that would be really a bad combination. Virological with Florian Kramer Hello and welcome to this episode of Virological. This was recorded on March 30th of 2026 in New York. So today we're going to talk about Nipa virus. That's a very interesting and very deadly virus and honestly that's really kind of my nightmare virus in a way and you will see why it's again deadly might be to some extent human to humans responsible at some point new date and you know become a new pandemic. So let's talk a little bit about this virus. Nipa virus is belongs to the Nipa virus basically per mix of virus that's distantly related to viruses like measles or mums. It has a negative sense single stranded RNA genome. What does that mean? Negative sense just means that that genome needs to be transcribed by the polymerase into positive strand RNA before proteins can be translated from it. When we look at the virion structure we have RNA genome on the inside that's covered by nuclear protein that protects the RNA genome. There's an associated polymerase and the phosphor protein and then we have a matrix protein that stabilizes the virion from the inside and then we have a lipid membrane and in this lipid membrane we have two gaicor proteins, two spike proteins. One is actually called G or gaicor protein and that's the one that attaches to our cells and then we have another one that's called F or fusion protein and that's the one that causes fusion of the viral membrane with the membrane of our cells so that the genome can get into our cells. And actually with this nipper virus the fusion happens on the surface of the cell not like with many other viruses after the virus would be taking up into tiny vesicles called endosomes and then fusion happens in the endosome. Not in this case, it seems to fuse really on the cell surface. A little bit more about the virus structure and how it looks like these viruses are about 150 nanometers in diameter. They're kind of roundish, not really round but kind of round shaped. We call this pleomorphic. In my opinion, nipper virus particles are like all baromixivirus particles pretty argy. That's just my personal opinion. I like influenza viruses. They look much nicer but yeah, again, that's personal preference. So yeah, we have these two spike proteins, the G and the F protein and the cheaper protein is, as I said, the one that binds to our cells and it does that by interacting with proteins on our cells. Two specific proteins, F-Rin-P2 and F-Rin-P3. That's already a hint that the virus can be pretty nasty. F-Rin-P3 is in humans found in cells in our brain and the virus that infects brain cells is never good thing. F-Rin-P2 is expressed in many cells of our body but also in the earways. That's also not a good thing because that would suggest that the virus can replicate in the upper and lower respiratory tract and that helps viruses typically to spread faster. Where does this virus come from? What's the history? It was first detected in September of 1998 in the Western part of Malaysia. There was an outbreak in pigs and in humans, initially the pigs were infected, they had respiratory symptoms and then the virus jumped over into humans. Humans had a different type of disease. It was more like an encephalitic disease, so brain infections basically but we'll get into the disease phenotype a little bit later. And the initial outbreak led to about 15 deaths in humans and it was really not clear what kind of bad touch and what kind of viruses causing these infections. Initially people thought maybe a Japanese bee ancephalitis which can also get amplified in pigs and then jump into humans but that usually happens via a vector, via mosquitoes which wasn't the case here. And then this outbreak started to spread and including to an area next to the Nipa river in Malaysia and that's where the name comes from. This outbreak grew relatively large, in the end there were 265 humans infected and 105 of them died. So that means that the virus has a relatively high case fidelity rate. Malaysia is growing a lot of pigs and then exports them into Singapore. So Singapore is right next to Malaysia, basically this little part on the bottom of Malaysia, on an island and so there were also 11 cases in slaughterhouses, slaughterhouse workers in Singapore and one death. You know we are used to having these viruses identified pretty quickly as we have seen with SARS-CoV-2 where you know very short period of time after the outbreak starts we know what's causing it but you know this is more than 25 years ago and back then it took basically from September of 1998 to March of 1999 to identify the virus that caused the outbreak and it was identified as a new paramix of virus in this case the Nipa virus. People also figured out relatively quickly that the virus was originating from bats that was circulating in bats and in this case really large bats. They actually called mega bats, in this case it's flying foxes and the virus was associated with two species of flying foxes. Terribles from bureaus that's the large flying fox and terribles hypo milanos which is the small flying fox. And these bats eat fruits and the problem was that in a lot of these big farms there were fruit trees and bats were coming in and they were you know eating the fruit on the trees and they're pretty messy either so a lot of the fruit that they're you know chewing on falls down that's contaminated with saliva and of course if they hang in these trees they probably also urinate and the fishes might fall down and then if there's pigs below these trees or close to these trees the pigs might feed on these bits and pieces of fruits that fall down that are contaminated they might also come in contact with urine of fishes and that's how they can get infected and then as I mentioned initially in Malaysia the disease the virus spread from pigs to humans. Pig farming was then restricted in some of these areas in Malaysia and in a way that took care of the issue so basically human infections and I think also pig infections disappeared in Malaysia although retrospective studies also identified that there probably have been earlier outbreaks in the area I think going back to 1996 but the virus resurfaced in 2001 in a different country in the area in Bangladesh and the way how people get infected there is different and it's also pretty interesting so there's not a lot of pig farming in Bangladesh but what people are doing is the harvest bomb sap so basically people clamp up into the bomb trees specific bombs that produce a sugary fluid a sugary sap if you cut them so you climb up into the tree you cut the tree and then you put a container there to collect the sap the juice that comes out of the tree and that's tasting sweet and people leave that container there overnight so that the juice accumulates and it's not only humans who like the juice but this flying foxes like it too so they stop there they basically drink from these containers to contaminate the bomb sap with their saliva and with that with the virus and that leads then to outbreaks in humans when they drink this raw bomb sap that has been harvested and these outbreaks are relatively frequent in Bangladesh there was one in 2003 2004 2005 2008 2011 2018 2019 and so on and so forth so you get it there's there's relatively frequent detections of human infections with these viruses and sometimes this can be up to 15 individuals so this can be a little bit larger outbreaks not always just a few cases and then recent years we have also seen smaller outbreaks in India and Kerala for example even to
2026 there was an outbreak in West Bengal and the problem here is that the case fatality rates in a lot of these outbreaks is very high. It's often between 50 to 75 percent, sometimes even as high as 90 percent. That's of course very concerning. So a little bit about the disease, the incubation time is between three to 14 days. Some rare cases it can be longer as in up to 45 days has been reported and the disease starts with relatively unspecific symptoms, similar to to actually an influenza infection fever, headache, cough, sore throat, so that the respiratory tract is involved. People get muscle aches, sometimes vomiting is involved and then over time unfortunately the virus reaches the central nervous system and then people develop neurological signs that are indicative of acute influenza flight is so acute brain infection and people might then fall into a coma and die. But there can also be severe respiratory distress, not just the upper respiratory symptoms that I mentioned earlier. And as I mentioned a lot of people who get infected actually die, so the case fatality rates are very high. If people survive the infection, there can often be long lasting consequences, persistent convulsions for example, but even personality changes have been reported. That's probably because you know people get infections in their brain. What is bad here is this combination of the virus ability to infect the respiratory tract and to infect the brain. In fact, the brain means like with with rabies for example that the outcome for the patient is probably not good. Those infections can be very deadly. In fact, the respiratory tract is also bad because that means that the virus potentially can spread via the air, via droplet, via aerosols and so it is known that NIPA virus can actually spread from humans to humans that has been described in Bangladesh. There were clusters where one person infected another person and there was an analysis done of cases between 2001 and 2007 that found that there are not four NIPA viruses 0.5. Now what's there are not? We discussed that in one of the initial episodes there are not describes how many people one infected person will infect. So if there are not this one, the virus keeps circulating in the population because if one person always infects another person, you know, the infection changed, keep going. If the R0 is below one, so in this case with NIPA the estimated was 0.5. That means there is some spread but the spread stops by itself. And that's good. The virus is not very infectious but it can jump from humans to humans. And I think the fear is that at some point it might mutate and might learn to do that better and better. And if it becomes more efficient in spreading, this could be a big issue because then you have a virus that efficiently jumps from humans to humans through the air, which means it's hard to stop. So a pandemic with a respiratory virus with a case of the illiterate between 50 and 90% would really be a disaster. And because of that, there is actually a lot of vaccine development for NIPA. A lot of movement there. One technology that is used is a vectored vaccines, the chatox vector for example, that's the same vector that was used for the AstraZeneca vaccine during the SARS-CoV-2 pandemic. I think they now have a NIPA vaccine in phase two. Then vesicular stomatitis virus vectors are used for development of NIPA vaccines. That's the same vector system that was used for the Ebola vaccine development pretty successfully because we have now an Ebola vaccine that's based on that vector. And then there's also a number of other approaches in clinical trials, including mRNA vaccines against NIPA. A lot of that is in phase one or phase two. And it would actually be very hard to get these vaccines licensed because with this infrequent outbreaks, it wouldn't be possible to really do efficacy studies and see how well the vaccine protects. But it's important to get these vaccines ready in case they're needed for a smaller outbreak or even a larger outbreak for pandemic preparedness. In addition to vaccines, there's also monocle antibodies that are in development for the treatment and prevention of these infections. One of these antibodies is called M102.4 that has already been compassionately used for treatment of infected individuals. But there is also more of these antibodies in development and having monocle antibody therapeutics for NIPA virus and related viruses would be very important. Since we're talking about related viruses, there's actually a similar virus that circulates in Australia, also in flying foxes. Australia has flying foxes too. And that virus is called handravirus. It's very closely related to NIPA virus. In this case, the virus infects mostly horses and then it can jump from horses to humans. In this case, a vaccine has been developed for horses and that has taken care of a lot of the problems with handravirus in Australia. But I think it's easier to vaccinate horses than flying foxes in Bangladesh. But this is also where this name of this group of viruses comes from, handnipa virus or handnipa viruses. It's basically a combination of handravirus and NIPA virus, so handnipa virus. And that's where they are called like that. And people are discovering more and more similar viruses that are related to NIPA viruses and handravirus. And the latest example is a virus that was discovered in shrews in Alabama and that's called camp hill virus. I think that was in the news about a year ago. It's not clear if that virus can infect humans and if it has actually any potential to cause disease in humans, but it's good to know that it is around. And maybe it's a good idea to stay away from shrews anyways. What is also worth mentioning is that this NIPA virus outbreak in Malaysia with the pigs was the basis for a movie that came out in 2011. The movie is called Contagion. It's really worth watching. It's super interesting. Specifically now after going through the SARS-CoV-2 pandemic, there's a lot of parallels in that movie. It's really maybe not entertaining, but an interesting movie to watch. I remember when that movie came out, I was a postdoc, Mount Sinai and Peter Belizeys lab and Peter was also the chair of our department here. And he decided to rent a movie theater, I think on the west side of Manhattan. And take out the whole department to watch the movie. And so we all went there and we watched the movie. And I think it was amazing. But Peter actually complained afterwards that it was not a Hollywood movie at all. There were not love stories in there. It wasn't very entertaining and it was too realistic to be an entertaining movie. So that kind of stuck with me. But I can really recommend watching it. All right. With that to summarize, NIPA virus is a virus that circulates in flying foxes in Southeast Asia. It sometimes infects humans through different ways either through infections of pigs and then it jumps from pigs to humans or through consumption of of this bombsap in Bangladesh probably consumption of fruits in India. It is relatively deadly. It has limited capacity to spread from humans to humans and there are vaccines and monocle antibody therapeutics in development. But it's really one of the viruses that I watch out for because this combination of infecting the respiratory tract and being capable of limited human to human transmission and its ability to infect the brain and be super deadly is of course something that's problematic and if the virus becomes better adapted to humans and starts to spread from humans to humans more efficiently, this could cause a really bad pandemic. All right. That's it for today. As always, if you have any questions, comments, suggestions, please just write an email to via
[email protected] and if you like this podcast, feel free to support it on Steadi. Thanks and until next time, bye. [Music]
PodcastTranscript AI