- NASA’s Psyche spacecraft
- Sickle Cell Breakthrough
- Facts for Prelims
1 . H9N2
Context: Union Health Ministry is closely monitoring the reported outbreak of H9N2 cases and clusters of respiratory illness in children in northern China. There is low risk to India from both the avian influenza case reported from China as well as the clusters of respiratory illness.
- Influenza A virus subtype H9N2 (A/H9N2) is a subtype of the species Influenza A virus (bird flu virus).
- Since 1998 a total of 86 cases of human infection with H9N2 viruses have been reported.
- H9N2 is the most common subtype of influenza viruses in Chinese chickens and thus causes great economic loss for the poultry industry, even under the long-term vaccination programs.
- Recent human infections with avian influenza virus revealed that H9N2 is the gene donor for H7N9 and H10N8 viruses that are infecting humans too.
- The crucial role of H9N2 viruses due to the wide host range, adaptation to both poultry and mammals and extensive gene reassortment.
- In China, which is regarded as a breeding ground of avian influenza viruses, the H9N2 virus has been detected in multiple avian species, including chicken, duck,quail, pheasant, partridge, pigeon, silky chicken, chukar and egret.
Does bird flu pose a threat to human beings?
- The WHO, in its literature on avian influenza, states that humans can be infected with virus subtypes H5N1, H7N9 and H9N2.
- Human cases of H5N1 avian influenza occur occasionally, but it is difficult to transmit the infection from person to person. When people do become infected, the mortality rate is about 60%.”
- On the H5N8 strain, the consensus is that human infection cannot be ruled out, although the likelihood is low. However, H5N6 infection, of a related clade (a descendant type) has occurred among humans.
- One case of the H9N2 strain, in a three-year old girl, was reported last October from Guangdong, China. It was mildly symptomatic and was detected during routine surveillance for Influenza-like illness.
How serious is avian flu for bird health?
- Avian Influenza (AI) is a highly contagious viral disease, affecting a variety of birds, including those connected with human consumption — chickens, ducks, turkeys, quails — as well as pet birds and wild birds.
- The World Organization for Animal Health, which collaborates with the World Health Organization (WHO) and the Food and Agriculture Organization (FAO), says HPAI virus strains H5N1, H5N2, H5N8, H7N8 have been identified in outbreaks, indicating active circulation. Infection histories point to H5N1 and H7N9 viruses posing a threat to human health as well.
- The FAO says wild birds act as a natural reservoir of AI viruses. Their migratory movement could bring these pathogens to poultry, waterfowl and other domestic birds through contact.
- The response to an outbreak is a containment strategy, which is primarily centred around removing the diseased birds through culling. Such mass destruction causes a severe impact on farmers.
- The H9N2 influenza virus can be transmitted by air droplet, dust, feed, or water.
- Chickens usually seemed to be healthy after the infection but some of them do show depression and ruffled feathers.
- The virus replicates itself in the trachea.
- It makes chickens more susceptible to secondary infections, especially Escherichia coli infections with a mortality rate of at least 10%.
- Also, the trachea or bronchi are easily embolized by mucus when the ventilation is poor, leading to severe respiratory disease and death.
- The overall risk assessment by WHO indicates a low probability of human to human spread and low case fatality rate among human cases of H9N2 reported to WHO so far.
2 . NASA’s Psyche Space Mission
Context: NASA’s Psyche spacecraft, currently over 16 million kilometres away in space, successfully fired a laser signal at Earth on November 14.
About the news
- The spacecraft is on its way to a unique metal-rich asteroid, orbiting the Sun between Mars and Jupiter.
- Scientists believe this asteroid is the nickel-iron core of an early planet, studying which could provide unique insights into the impenetrable iron core of our own planet.
- Simultaneously, it will also carry out another mission that might hold the key to future space exploration.
About Psyche Space Mission
- Psyche is a NASA mission to study a metal-rich asteroid with the same name, located in the main asteroid belt between Mars and Jupiter.
- Psyche is the first mission to explore an asteroid with a surface that contains substantial amounts of metal rather than rock or ice.
- The spacecraft is propelled by solar electric propulsion. The solar propulsion system’s thrusters use electromagnetic fields to accelerate and push out charged atoms, or ions, of the neutral gas xenon.
- The expelled ions create the thrust that pushes Psyche through space and emit a blue glow. With no atmospheric drag to hold it back, the spacecraft will accelerate to speeds of up to 124,000 mph (200,000 kph) relative to Earth during its interplanetary journey to the asteroid belt.
- NASA’s DSOC (Deep Space Optical Communications) demonstration, carried by the Psyche spacecraft, will send and receive test data using an invisible near-infrared laser, which can transmit data at 10 to 100 times the bandwidth of conventional radio wave systems used on spacecraft today.
- DSOC will demonstrate operations for nearly two years after NASA’s Psyche mission launch while en route to its 2026 Mars flyby.
- DSOC will take optical communications into deep space for the first time and set the foundation for establishing higher data-rate returns from future robotic and human missions to Mars and beyond.
- Psyche is the 14th mission selected as part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama.
3 . Sickle Cell Breakthrough
Context: The UK drug regulator last week approved a gene therapy for the cure of sickle cell disease and thalassaemia, seen as a landmark breakthrough by many.
About the news
- This is the first licensed therapy in the world based on the gene editing technology Crispr-Cas9 that earned its innovators a Nobel Prize in 2020.
- Called Casgevy, the therapy edits the faulty gene that leads to these blood disorders, potentially curing the person for life. So far, the only permanent treatment has been a bone marrow transplant, for which a closely matched donor is needed.
How does the therapy work?
- Both sickle cell disease and thalassaemia are caused by errors in the gene for haemoglobin, a protein in the red blood cells that carry oxygen to organs and tissues.
- The therapy uses the patient’s own blood stem cells, which are precisely edited using Crispr-Cas9. A gene called BCL11A, which is crucial for switching from foetal to adult haemoglobin, is targeted by the therapy.
- Foetal haemoglobin, which is naturally present in everyone at birth, does not carry the same abnormalities as adult haemoglobin. The therapy uses the body’s own mechanisms to start producing more of this foetal haemoglobin, alleviating the symptoms of the two conditions.
What are sickle cell disease and thalassaemia?
- The genetic error in sickle cell disease leads to red blood cells assuming a crescent shape.
- Unlike the disc shaped normal cells, the sickle-like cells cannot move around easily in the vessels, resulting in blocked blood flow. This can lead to episodes of severe pain, life-threatening infections, anaemia, or a stroke.
- An estimated 30,000-40,000 children in India are born with the disorder every year.
- The symptoms manifest in people who inherit a pair of damaged genes from both parents. Those who carry only one copy of the gene from one parent can lead a normal life. This is the same as thalassaemia, in which people who inherit a pair of genes from both parents experience symptoms like severe anaemia.
- Thalassaemia leads to low levels of haemoglobin, leading to fatigue, shortness of breath, and irregular heartbeats. People with the condition need blood transfusions throughout their life. The transfusions also lead to accumulation of excess iron in the body, for which they need chelation.
- India has the largest number of children with thalassaemia major in the world — about 1-1.5 lakh.
What have the trials shown so far?
- For sickle cell disease, 45 people received Casgevy. Only 29 of these patients had been in the trial long enough for the interim analysis on which the approval is based. All but one of these 29 trial participants had no severe pain crises for at least 12 months after treatment.
- The therapy has been administered to 54 persons with thalassaemia for the trial. Of them, 42 were in the trial long enough for the interim analysis. 39 of the 42 patients did not need a transfusion for at least 12 months after the treatment. The need for transfusion dropped by 70% in the other three.
How is the therapy prepared and given?
- Casgevy is a one-time treatment for which the doctor has to first collect blood stem cells from the bone marrow using a process called apheresis which is used to filter out the blood for different components.
- The cells are then sent to the manufacturing site where it takes about six months for them to be edited and tested.
- Before a transplant with the edited cells, the doctor gives a conditioning medicine for a few days to clear the bone marrow of other cells that will be replaced by the modified cells.
- The patient has to stay in hospital for at least a month so that the edited cells take up residence in the bone marrow and start making red blood cells with normal haemoglobin.
- Side effects from the treatment are similar to those associated with autologous stem cell transplants, including nausea, fatigue, fever and increased risk of infection.
What are the challenges of this treatment?
- Although the price of the therapy hasn’t been announced, it is likely to be very high. Estimates suggest it could be as much as $2 million per patient, which is in line with other gene therapies.
- Cost is one of the biggest limitations of newer gene therapies, along with the absence of local manufacturing facilities, which means that the harvested blood stem cells have to be sent across countries.
4 . Facts for Prelims
- GPS spoofing is the surreptitious replacement of a true satellite signal that can cause a GPS receiver to output an erroneous position and time.
- GPS spoofing happens when someone uses a radio transmitter to send a counterfeit GPS signal to a receiver antenna to counter a legitimate GPS satellite signal.
- Most navigation systems are designed to use the strongest GPS signal, and the fake signal overrides the weaker but legitimate satellite signal.
- It allows hackers to interfere with navigation systems without operators realizing it.
- The Union government has added the Computer Emergency Response Team (CERT-In) among a list of organisations that are exempted from the ambit of the Right to Information Act (RTI).
- The CERT-In is the national nodal agency for responding to computer security incidents as and when they occur.
- One of its primary objectives is enhancing “security awareness among common citizens”.
- It functions under Ministry of Electronics and Information Technology.