Novel antibody fragments (nanobodies) against SARS-CoV-2, the virus that causes Covid-19, have been detected and further developed by an international research team led by the University of Bonn (Germany).
➤ Nanobodies Against SARS-CoV-2:
- Produced along with Antibodies:
- On injection of the surface protein of the coronavirus into an alpaca and a llama, their immune system produced antibodies directed against the virus and a simpler antibody variant that can serve as the basis of nanobodies.
- More Effective:
- They had also combined the nanobodies into potentially particularly effective molecules, which attack different parts of the virus simultaneously. This new approach could prevent the pathogen from evading antibodies' effect through mutations.
- Nanobodies appear to trigger a structural change before the virus encounters its target cell - an unexpected and novel action mode. The difference is likely to be irreversible; the virus is therefore no longer able to bind to host cells and infect them.
- Antibodies are an essential weapon in the immune system's defence against infections.
- They bind to the surface structures of bacteria or viruses and prevent their replication.
- One strategy in the fight against disease is therefore to produce effective antibodies in large quantities and inject them into patients. However, producing antibodies is difficult and time-consuming; they are, therefore, probably not suitable for widespread use.
- Nanobodies are antibody fragments that are so simple that they can be produced by bacteria or yeast, which is less expensive.
- These are antibodies with a single variable domain located on a heavy chain, also known as VHH antibodies.
- These are often seen as an alternative to conventional antibodies and have significant differences in both production and use that influence their suitability.
➤ Difference between Nanobodies and Conventional Antibodies:
- Difference in Structure and Domains:
- Conventional antibodies have two variable domains, called VH and VL, which offer each other stability and binding specificity.
- Nanobodies have VHH domains and lack VL domains, but are still highly stable. Lacking the VL domain also means nanobodies have a hydrophilic (tending to dissolve in water) side.
- The hydrophilic side means they do not have solubility issues and aggregation otherwise associated with conventional antibodies.
- Nanobody production follows many of the same protocols as used in traditional antibody production. However, it also has distinct advantages not available with traditional antibodies, such as improved screening, improved isolation techniques, and no animal sacrifice.
- Nanobodies are much smaller than classic antibodies and they, therefore, penetrate the tissue better and can be produced more easily in larger quantities.
- Nanobodies are stable in a wide range of temperatures, remaining functional at temperatures as high as 80°C. As a bonus, the nanobody's unfolding due to high temperatures is fully reversible, unlike conventional antibody fragments.
- Nanobodies are also stable at extreme pH levels and survive exposure to gastric fluid.
- Nanobodies are also compatible with genetic engineering methods, which allow alteration of amino acids to improve binding.
➤ Limitations of Nanobodies:
- Monoclonal and polyclonal antibodies are slightly safer to produce than nanobodies, as there are biohazards involved in nanobody production not present for conventional antibody production.
- The biohazards result mainly from hazardous bacteriophages (any of a group of viruses that infect bacteria) for the selection of nanobodies. Other sources include plasmids, antibiotics, and recombinant DNA. These materials require safe disposal.
- Polyclonal antibodies are made using several different immune cells.
- Monoclonal antibodies are made using identical immune cells that are all clones of a specific parent cell.
Bird Flu Threat
Hundreds of crows have died in Rajasthan, prompting authorities to sound a bird flu alert in the state.
- Bird flu, also known as Avian influenza (AI), is a highly contagious viral disease affecting several species of food-producing birds (chickens, turkeys, quails, guinea fowl, etc.) as well as pet birds and wild birds.
- Occasionally, mammals, including humans, may contract avian influenza.
- Influenza viruses are grouped into three types; A, B, and C. Only type A is known to infect animals and is zoonotic, meaning it can infect animals and also humans. Type B and C mostly infect humans and typically cause a mild disease.
- Avian influenza virus subtypes include A(H5N1), A(H7N9), and A(H9N2).
- Influenza viruses are classified into subtypes based on two surface proteins, Hemagglutinin (HA) and Neuraminidase (NA). For example, a virus with an HA 7 protein and NA 9 protein is designated as subtype H7N9.
- Highly Pathogenic Avian Influenza (HPAI) A(H5N1) virus occurs mainly in birds and is highly contagious among them.
- HPAI Asian H5N1 is especially deadly for poultry.
- Avian Influenza outbreaks can lead to devastating consequences for the country, particularly the poultry industry.
- Farmers might experience a high level of mortality in their flocks, with rates often around 50%.
Strict biosecurity measures and good hygiene are essential in protecting against disease outbreaks.
If the infection is detected in animals, a policy of culling infected and contact animals is normally used in an effort to contain rapidly, control and eradicate the disease.
➤ India's Status:
- Previously in 2019, India was declared free from Avian Influenza (H5N1), which had also been notified to the World Organization for Animal Health (OIE).
- The status will last only till another outbreak is reported.
➤ World Organization for Animal Health
- The OIE is an intergovernmental organisation responsible for improving animal health worldwide.
- It is recognised as a reference organisation by the World Trade Organization (WTO).
- In 2018, it had a total of 182 Member Countries. India is a member country. It is headquartered in Paris, France.
Boost to Defence Exports
The Union Cabinet recently approved the Akash surface-to-air missile export to "friendly countries". It formed a committee led by the Defence Minister to expedite the approval of defence platform exports.
- This committee would authorise subsequent export of major indigenous platforms to various countries.
- The export version of Akash will be different from the system currently deployed with the Indian armed forces.
- The Cabinet approval will facilitate Indian manufactures to participate in RFI/RFP issued by various countries. o A request for information (RFI) is used when the owner wants several contractors to provide potential solutions. In contrast, a request for proposal (RFP) is used in a bidding process to solicit offers for a project.
- So far, Indian defence exports included parts/ components etc. The export of big platforms was minimal.
- This initiative of the Cabinet would help the country improve its defence products and make them globally competitive.
- It would be a significant step under Atma Nirbhar Bharat,
- Besides Akash, there is interest in other major platforms like the coastal surveillance system, radars and air platforms.
➤ Akash Missile
- Akash is India's first indigenously produced medium-range Surface to Air missile that can engage multiple targets from multiple directions.
- The all-weather missile can engage targets at a speed 2.5 times more than the speed of sound and can detect and destroy targets flying at low, medium and high altitudes.
- The Akash missile system has been designed and developed as part of India's 30-year-old integrated guided-missile development programme (IGMDP), including other missiles like Nag, Agni, Trishul, and Prithvi.
➤ Range and Capability:
- The nuclear-capable missile can fly at a speed of up to Mach 2.5 (nearly 860 meters per second) at a maximum height of 18 km.
- It can strike enemy aerial targets like fighter jets, drones, cruise missiles, air-to-surface missiles, and ballistic missiles from a distance of 30 km.
➤ Unique features of Akash:
- The missile is unique because it can be launched from mobile platforms like battle tanks or wheeled trucks. It has a nearly 90% kill probability.
- The missile is supported by the indigenously developed radar called 'Rajendra' that can handle highly-manoeuvring multiple targets from multiple directions in a group or autonomous mode.
- The missile is reportedly cheaper and more accurate than US' Patriot missiles due to its solid-fuel technology and high-tech radars.
➤ Manufactured by:
The missile system is designed and developed by the Defence Research and Development Organisation (DRDO)
➤ India's Defence Exports:
- As per the data published by the Stockholm International Peace Research Institute, or SIPRI, in March 2020, India is ranked 23rd in the list of major arms exporters for 2015-2019 and 19th for 2019.
- The Ministry of Defence's annual report 2018-19 records that the defence exports were worth Rs 10,745 crore, a growth of more than 100% from 2017-18 (Rs 4,682 crore) and over 700% since 2016-17 (Rs 1,521 crore).
- It's share of global arms exports is only 0.17%.
- The current government has been emphasising defence manufacturing in India to build up the country's manufacturing base, ensure jobs for its youth, and bring down India's arms import bill.
- India's target was to export 5 billion USD worth of military hardware by 2025.
Trans Fatty Acids
Via an amendment to the Food Safety and Standards (Prohibition and Restriction on Sales) Regulations 2011, the Food Safety and Standards Authority of India (FSSAI) has limited the amount of trans fatty acids (TFA) in oils and fats to 3% for 2021 and 2% for 2022, down from the existing permissible limit of 5%.
The Regulations deal with the prohibitions and restriction on sales of various food products, ingredients and their admixtures.
- The revised regulation applies to edible refined oils, vanaspati (partially hydrogenated oils), margarine, bakery shortenings, and other mediums of cooking such as vegetable fat spreads and mixed fat spreads.
- As per the World Health Organisation (WHO), approximately 5.4 lakh deaths occur each year globally because of the intake of industrially produced trans fatty acids.
- The FSSAI rule comes at the time of a pandemic where the burden of non-communicable diseases (NCD) has risen.
- Trans-fat consumption is a significant risk factor for cardiovascular diseases. o Cardiovascular diseases account for most NCD deaths.
- Previously, in 2011, India first passed a regulation that set a TFA limit of 10% in oils and fats, which was further reduced to 5% in 2015.
- Trans fatty acids (TFAs) or Trans fats are the most harmful type of fats which can have much more adverse effects on a human body than any other dietary constituent.
- These fats are primarily produced artificially but a small amount also occurs naturally. Thus in our diet, these may be present as Artificial TFAs and/ or Natural TFAs.
- Artificial TFAs are formed when hydrogen is made to react with the oil to produce fats resembling pure ghee/butter.
- In our diet the major sources of artificial TFAs are the partially hydrogenated vegetable oils (PHVO)/ vanaspati/ margarine while the natural TFAs are present in meats and dairy products, though in small amounts.
TFA containing oils can be preserved longer, they give the food the desired shape and texture and can easily substitute 'Pure ghee'. These are comparatively far lower in cost and thus add to profit/saving.
➤ Harmful effects:
- TFAs pose a higher risk of heart disease than saturated fats. While saturated fats raise total cholesterol levels, TFAs raise total cholesterol levels and reduce the good cholesterol (HDL), which helps to protect us against heart disease.
- It is also associated with a higher risk of developing obesity, type 2 diabetes, metabolic syndrome, insulin resistance, infertility, certain types of cancers and can also lead to compromised fetal development causing harm to the yet to be born baby.
- Metabolic syndrome includes high blood pressure, high blood sugar, excess body fat around the waist and abnormal cholesterol levels. The syndrome increases a person's risk of heart attack and stroke.
➤ Efforts to reduce their intake:
- FSSAI launched a "Trans Fat Free" logo for voluntary labelling to promote TFA-free products. Bakeries can use the label, local food outlets and shops for preparations containing TFA not exceeding 0.2 per 100 g/ml.
- FSSAI launched a new mass media campaign "Heart Attack Rewind" to eliminate industrially produced trans fat in the food supply by 2022.
- "Heart Attack Rewind" is a follow-up to an earlier campaign called "Eat Right", launched in July, 2018.
- Edible oil industries took a pledge to reduce salt, sugar, saturated fat and trans fat content by 2% by 2022.
- Swasth Bharat Yatra, an initiative started under the "Eat Right" campaign is a Pan-India cyclothon to engage citizens on food safety issues, combating food adulteration and healthy diets.
- WHO launched a REPLACE campaign in 2018 for global-level elimination of trans-fats in industrially produced edible oils by 2023.
Two Dimensional Electron Gas
Scientists at the Institute of Nano Science and Technology (INST) in Mohali, Punjab, have developed a two-dimensional (2D) electron gas with ultra-high mobility (2DEG).
➤ Two Dimensional Electron Gas (2DEG):
- It is an electron gas that is free to move in two dimensions, but tightly confined in the third. This tight confinement leads to quantized energy levels for motion in the third direction. Thus the electrons appear to be a 2D sheet embedded in a 3D world.
- One of the most significant recent developments in semiconductors has been the achievement of structures in which the electronic behavior is essentially two-dimensional (2D).
- Most 2DEGs are found in transistor-like structures made from semiconductors.
- 2DEG is a valuable system for exploring superconductivity magnetism's physics and coexistence.
- Superconductivity is a phenomenon whereby
- A charge moves through a material without resistance. In theory this allows electrical energy to be transferred between two points with perfect efficiency, losing nothing to heat. Cause for Development of 2DEG:
- The need to attain new functionalities in modern electronic devices has led to the manipulation of property of an electron called spin degree of freedom and its charge. This has given rise to an altogether new spin-electronics field or 'spintronics'.
- The manipulation of electron spin offers new dimensions for basic and applied research, and the potential for new capabilities for electronics technology. This motivates studies of spin-polarized electrons in a high mobility two-dimensional electron gas (2DEG).
- Spintronics is the study of the intrinsic spin of the electron and its
- In addition to its fundamental electric charge, it associated magnetic moment in solid-state devices.
- It has been realized that a phenomenon called the 'Rashba effect', which consists of splitting spin-bands in an electronic system, might play a key role in spintronic devices.
- Rashba Effect: Bychkov-Rashba effect, it is a momentum-dependent splitting of spin bands in bulk crystals and low-dimensional condensed matter systems.
➤ Mechanism and Importance:
- Due to the high mobility of the electron gas, electrons do not collide inside the medium for a long distance and hence do not lose memory and information.
- Hence, it can speed up the transfer of quantum information and signal from one part of a device to another and increase data storage and memory.
- Since they collide less during their flow, their resistance is meagre, and hence they don't dissipate energy as heat.
- So, such devices do not heat up quickly and needless input energy to operate.