20 March 2023

– Narmada Khare

In January 2022, around the time that the Omicron variant of SARS-CoV-2 started spreading rapidly, a team of researchers at the Indian Institute of Science (IISc) led by Shashank Tripathi, Assistant Professor at the Department of Microbiology & Cell Biology, and Centre for Infectious Diseases Research, noticed that there was an unusually high increase in the number of recombinant strains of the Omicron variant.

The team analyzed genomic sequences of all the viral strains that appeared between November 2019 and July 2022 in various databases worldwide. In a study published in the Journal of Medical Virology, they have identified several new mutations that accumulated through recombination at a high rate and affected viral proteins, especially different parts (domains) of the viral spike protein. These domains – such as the Receptor Binding Domain (RBD) and N Terminal Domain (NTD) – are known to be involved in the virus-host binding and have also been reported as sites of attack by the host’s immune system. The team showed that, with the aid of these mutations, several such Omicron recombinant and mutant strains were able to escape from the host’s defenses and bind more tightly to the host cell.

Their observations add to growing evidence about how efficient new strains of the virus are at escaping immune attack and at causing infections.

Recombination in SARS-CoV-2 viruses (Credit: Rishad Shiraz) 

Viruses like SARS-CoV-2 are known to change constantly, making it hard for our immune system to identify and destroy them. This is a major concern when generating vaccines. The genetic material in SARS-CoV-2 is a long single-stranded RNA. In addition, the protein that is required to make copies of this RNA – RNA polymerase – is known to be error-prone in this virus.

Viruses can evolve via one of two mechanisms: mutation or recombination, explains Tripathi. “This is a strategy to increase its genetic diversity.” The polymerase doesn’t just allow mutations to accumulate, it often also causes recombination to happen between different strains of the virus. This is possible when there is co-infection – when a host cell is infected by more than one strain of the virus. “When copying the viral RNA, the polymerase can jump from one RNA template to another that is nearby,” says Tripathi. If the nearby sequence is that of another strain, then the new copy will be a recombinant or a hybrid of the two parental strains. Tripathi says that there are currently more than 35 recombinants of SARS-CoV-2. For example, one of the more efficient variants, XBB, which emerged in 2022, was born from recombination between two other versions of Omicron, he explains.

There are two possible reasons for the increase in these recombination events, according to the study. First, the number of infections and co-infections were high during the 2022 Omicron wave. Second, the team noticed that a specific mutation has appeared in a viral gene for an exonuclease, a protein that can cleave RNA and is believed to be involved in recombination. Tripathi explains, “Our findings show that the virus is not cooling down but is actually warming up as far as mutations go.”

Because enhanced recombination can increase the chances of new strains emerging, tracking such recombinations through regular sequencing of the virus is crucial, the researchers say.

REFERENCE: 
Shiraz R, Tripathi S, Enhanced recombination among omicron subvariants of SARS-CoV-2 contributes to viral immune escape, Journal of Medical Virology (2023). 

https://onlinelibrary.wiley.com/doi/10.1002/jmv.28519

CONTACT: 
Shashank Tripathi
Assistant Professor
Department of Microbiology & Cell Biology and Centre for Infectious Diseases Research
Indian Institute of Science (IISc)
Phone: +91 8022932884
Email: shashankt@iisc.ac.in
Website: https://cidr.iisc.ac.in/shashank/
NOTE TO JOURNALISTS: 

1. a) If any of the text in this release is reproduced verbatim, please credit the IISc press release.
2. b) For any queries about IISc press releases, please write to news@iisc.ac.inor pro@ac.in.

22 March 2023 

Power Finance Corporation Limited (PFC) has made a generous commitment to support the establishment of a state-of-the-art building that will house the Interdisciplinary Centre for Energy Research (ICER) at the Indian Institute of Science (IISc). An MoA between PFC and IISc was signed on 21 March 2023 in the presence of Mr Ravinder Singh Dhillon, CMD, PFC, and Prof Govindan Rangarajan, Director, IISc, along with other representatives from PFC and IISc.

The support from PFC comes at an opportune time when countries across the globe are focusing on net zero technologies to mitigate the environmental impact of conventional energy generation. The state-of-the-art building for ICER will foster cutting-edge fundamental and applied research on various energy-related areas, with special focus on green hydrogen generation. It will be constructed at a cost of Rs 60 crore over the next two years. The building will house modern labs, seminar rooms, classrooms and faculty rooms, as well as facilities for developing energy-related products and prototypes. It will also support PhD and Master’s programmes, and foster several collaborative programmes with academic and industry partners.

The Interdisciplinary Centre for Energy Research (ICER), among the newest research centres at IISc, was conceived in 2012 as a part of the Institute’s post-centenary vision to pursue socially relevant research in line with the Government of India’s national missions. It has since made significant contributions in several areas. For example, its ongoing research on generating green hydrogen from biomass has reached the stage of real-world demonstration in fuel cell buses. It has also established India’s first closed-loop supercritical carbon dioxide-based Brayton cycle power block. ICER has collaborations with several organisations and industries within India and abroad.

“We are extremely grateful to Power Finance Corporation Limited for generously funding a new building for the Interdisciplinary Centre for Energy Research,” said Prof Rangarajan. “Over the past decade, the Centre has made great strides in energy research and pioneered several indigenous technologies. With climate change accelerating at an alarming pace, it is imperative for academia and industry to join hands and develop novel solutions that can help us achieve net zero emissions.”

The new building will significantly accelerate advanced research in indigenous green hydrogen and net zero technologies, and increase capacity building through training and degree programmes.

CONTACT: 
IISc Office of Communications | news@iisc.ac.in

24 March 2023

– Prarthana Ghosh Dastidar

Researchers at the Indian Institute of Science (IISc) are working on designing antennas that can empower 6G technology, which is instrumental in realising efficient V2X (Vehicle to Everything) communications.

In a recent study, the team, led by Debdeep Sarkar, Assistant Professor at the Department of Electrical Communication Engineering, shows how self-interference in full-duplex communication antennas can be reduced, and consequently the movement of signals across the communication network can be faster and more bandwidth-efficient. Such full-duplex antennas are particularly helpful for applications that require almost instantaneous relay of commands, like driverless cars.

Simplified architecture of intelligent transportation system (ITS) showing V2X Connectivity (Credit: Jogesh Chandra Dash and Debdeep Sarkar)

Full-duplex antennas consist of a transmitter and a receiver to send and receive radio signals. Traditional radio transceivers are half duplex, which means that they either use signals of different frequencies for sending and receiving or there is a time lag between the signal transmitted and the signal received. This time lag is needed to ensure that there is no interference – the signals going back and forth should not cross paths with each other, similar to two people talking to each other at the same time, without pausing to listen to the other. But this also compromises the efficiency and speed of signal transfer.

In order to transmit data much faster and more efficiently, full-duplex systems are required, where both the transmitter and receiver can operate signals of the same frequency simultaneously. For such systems, eliminating self-interference is key. This is what Sarkar and his IoE-IISc postdoctoral fellow, Jogesh Chandra Dash, have been working on for the past few years.

“The broad objective of the research is that we want to eliminate the signal that is coming as self-interference,” says Sarkar. There are two ways to cancel self-interference – passive and active. Passive cancellation is done without any additional instrument, by just designing the circuit in a certain way (for example, increasing the distance between the two antennas). Active cancellation relies on additional components like signal processing units to cancel out the self-interference. But the components needed for these steps can make the antenna bulky and expensive. What is needed, instead, is a compact, cost-efficient antenna which can be easily integrated into the rest of the circuitry of any device.

The antenna developed by Sarkar and Dash, by virtue of its design, relies on passive interference, allowing it to operate as a full-duplex system. It consists of two ports, either of which can act as transmitter or receiver. The two ports are isolated from each other by electromagnetic tools called metallic vias. Metallic vias are holes drilled into the metal surface of the antenna which disrupt the electric field. In this way, the team managed to cancel out most of the interference passively, alongside achieving a cost-effective and compact design.

“We are eliminating all the conventional techniques for self-interference cancellation, and we are integrating a very simple structure that can be installed in a car,” says Dash.

In the immediate future, the team plans to optimise their device so that it can entirely remove passive interference, and reduce the overall size of the antenna. Then, it can easily be fixed onto a vehicle where it can transmit and receive data at very high speeds, bringing driverless operation as well as 6G mobile connectivity closer to reality.

REFERENCES:

Dash JC, Sarkar D, A Co-Linearly Polarized Shared Radiator Based Full-Duplex Antenna with High Tx-Rx Isolation using Vias and Stub Loaded Resonator, IEEE Transactions on Circuits and Systems-II: Express Briefs (2023)
https://ieeexplore.ieee.org/document/10024384

Dash JC, Sarkar D, A Co-Linearly Polarized Full-Duplex Antenna with Extremely High Tx-Rx Isolation, IEEE Antennas and Wireless Propagation Letters (2022)
https://ieeexplore.ieee.org/document/9841615

Dash JC, Sarkar D, Microstrip Patch Antenna System with Enhanced Inter-Port Isolation for Full-duplex/MIMO Applications, IEEE Access (2021)
https://ieeexplore.ieee.org/document/9618907

CONTACT:
Debdeep Sarkar
Assistant Professor
Department of Electrical Communication Engineering
Indian Institute of Science (IISc)
Email: debdeep@iisc.ac.in
Phone: +91-8022933158
Website: https://ece.iisc.ac.in/~debdeeps/

Jogesh Chandra Dash
IoE-IISc Postdoctoral Fellow
Department of Electrical Communication Engineering
Indian Institute of Science (IISc)
Email: jogeshdash@iisc.ac.in

NOTE TO JOURNALISTS:
a) If any of the text in this release is reproduced verbatim, please credit the IISc press release.
b) For any queries about IISc press releases, please write to news@iisc.ac.in or pro@ac.in.