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Study Reveals Essential Genes That Help Tuberculosis Survive Airborne Transmission

Tuberculosis is a respiratory disease caused by Mycobacterium tuberculosis, a bacterium that predominantly affects the lungs and spreads through droplets released by an infected person

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Image credit: Jomar Junior from Pixabay

Tuberculosis thrives in the lungs, but when the bacteria causing the disease are expelled into the air, they face a much harsher environment with drastic changes in pH and chemistry. Understanding how these bacteria survive this airborne journey is essential for their persistence, yet little is known about the mechanisms that protect them as they move from one host to another.

Now, MIT researchers and their collaborators have identified a family of genes that are crucial for the bacterium’s survival specifically when exposed to the air, likely offering protection during its transmission.

Previously, many of these genes were thought to be nonessential, as they didn’t appear to affect the bacteria’s role in causing disease when introduced into a host. This new study, however, suggests that these genes are vital for transmission rather than proliferation.

“There is a blind spot in our understanding of airborne transmission, especially regarding how a pathogen survives sudden environmental changes as it circulates in the air,” says Lydia Bourouiba, head of the Fluid Dynamics of Disease Transmission Laboratory, associate professor of civil and environmental engineering, mechanical engineering, and core faculty member at MIT’s Institute for Medical Engineering and Science. “Now, through these genes, we have an insight into the tools tuberculosis uses to protect itself.”

The team’s findings, published this week in Proceedings of the National Academy of Sciences, could lead to new tuberculosis therapies that target both infection and transmission prevention.

“If a drug targeted the products of these genes, it could effectively treat an individual and, even before that person is cured, prevent the infection from spreading,” says Carl Nathan, chair of the Department of Microbiology and Immunology and the R.A. Rees Pritchett Professor of Microbiology at Weill Cornell Medicine.

Nathan and Bourouiba co-senior authored the study, which includes MIT collaborators and Bourouiba’s mentees from the Fluids and Health Network: co-lead author postdoc Xiaoyi Hu, postdoc Eric Shen, and students Robin Jahn and Luc Geurts. The research also involved collaborators from Weill Cornell Medicine, the University of California at San Diego, Rockefeller University, Hackensack Meridian Health, and the University of Washington.

Pathogen’s Perspective

Tuberculosis is a respiratory disease caused by Mycobacterium tuberculosis, a bacterium that predominantly affects the lungs and spreads through droplets released by an infected person, typically when they cough or sneeze. Tuberculosis remains the leading cause of death from infection, except during global viral pandemics.

“In the last century, we’ve seen the 1918 influenza pandemic, the 1981 HIV/AIDS epidemic, and the 2019 SARS-CoV-2 pandemic,” notes Nathan. “Each virus has caused significant loss of life, but after they subsided, we were left with the ‘permanent pandemic’ of tuberculosis.”

Much of the research on tuberculosis focuses on its pathophysiology—how the bacteria infect a host—along with diagnostic and treatment methods. For their new study, Nathan and Bourouiba turned their attention to tuberculosis transmission, specifically exploring how the bacteria defend themselves during airborne transmission.

“This is one of the first efforts to study tuberculosis from an airborne perspective, investigating how the organism survives harsh changes in the environment during transmission,” says Bourouiba.

Critical Defense

At MIT, Bourouiba studies fluid dynamics and how droplet behaviors can spread particles and pathogens. She partnered with Nathan, who investigates tuberculosis and the genes that the bacteria rely on throughout their life cycle.

To explore how tuberculosis survives in the air, the team aimed to replicate the conditions the bacterium encounters during transmission. They first worked to develop a fluid with similar viscosity and droplet sizes to those expelled by a person coughing or sneezing. Bourouiba points out that previous research on tuberculosis relied on liquid solutions that are used to grow the bacteria. However, these liquids differ significantly from the fluids tuberculosis patients expel.

Furthermore, the fluid typically sampled from tuberculosis patients, like sputum for diagnostic tests, is thick and sticky, which makes it inefficient at spreading and forming inhalable droplets. “It’s too gooey to break into inhalable droplets,” Bourouiba explains.

Through her research on fluid and droplet physics, the team determined a more accurate viscosity and droplet size distribution for tuberculosis-laden microdroplets in the air. They also analyzed the composition of droplets by studying infected lung tissue samples. They then created a fluid that mimicked the viscosity, surface tension, and droplet size that would be released into the air when a person exhales.

Next, the team deposited different fluid mixtures onto plates as tiny droplets, measuring how they evaporated and what structures they left behind. They discovered that the new fluid shielded the bacteria at the center of the droplet, unlike traditional fluids where bacteria were more exposed to the air. The realistic fluid also retained more water.

The team then infused the droplets with bacteria carrying genes with various knockdowns to see how the absence of specific genes affected bacterial survival during evaporation.

They evaluated over 4,000 tuberculosis genes and identified a family of genes that became crucial in airborne conditions. Many of these genes are involved in repairing damage to oxidized proteins, such as those exposed to air, while others are responsible for breaking down irreparably damaged proteins.

“What we found is a lengthy list of candidate genes, some more prominently involved than others, that could play a critical role in helping tuberculosis survive during transmission,” Nathan says.

While the experiments cannot fully replicate the bacteria’s biophysical transmission (as droplets fly through the air and evaporate), the team mimicked these conditions by placing plates in a dry chamber to accelerate droplet evaporation, similar to what happens in flight.

Going forward, the researchers are developing platforms to study droplets in flight under various conditions. They plan to further investigate the role of the newly identified genes in more realistic experiments, potentially weakening tuberculosis’s airborne defenses.

“The idea of waiting to diagnose and treat someone with tuberculosis is an inefficient way to stop the pandemic,” Nathan says. “Most individuals who exhale tuberculosis haven’t been diagnosed yet, so we need to interrupt its transmission. Understanding the process is key, and now we have some ideas.”

EP Staff is the editorial team at EdPublica, an independent media organisation focused on science, education, environment and public policy. The team produces evidence-based news, features, explainers and analysis on issues that shape society and everyday life.

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Over 1,000 Cancer Drug Formulations Become Cheaper Across India

India has reduced prices across 1,031 anti-cancer medicine formulations, with the government estimating annual consumer savings of 3,502 crore rupees.

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Assorted tablets, capsules and pharmaceutical medicines representing the cost of cancer drugs and medicine affordability in India.
India has reduced prices across 1,031 anti-cancer medicine formulations, with estimated annual consumer savings of 3,502 crore rupees. Representational image. Image credit: Stevepb/ Pexels

Cancer treatment can involve months or even years of medication, repeated diagnostic tests, hospital visits and specialised procedures. For many Indian families, the financial strain continues long after the initial diagnosis. Against this backdrop, a government intervention to reduce the prices of more than 1,000 anti-cancer drug formulations has come into effect on November 9. The National Pharmaceutical Pricing Authority (NPPA), under the Department of Pharmaceuticals, has rationalised trade margins on 137 identified non-scheduled anti-cancer drugs. The government estimates that the revised prices will save consumers 3,502.31 crore rupees annually.

According to the Ministry of Chemicals and Fertilizers, 76 pharmaceutical companies have reported revised maximum retail prices (MRPs) for 1,225 formulations covering 121 drugs. Of these, 1,031 formulations have registered price reductions. Around 600 brands have reported reductions exceeding 50%, while the highest reduction stands at 96.45%.

The intervention is significant given the scale of cancer in India. The Indian Council of Medical Research’s National Cancer Registry Programme estimated 15.69 lakh new cancer cases in 2025. Breast, lung and mouth cancers featured among the leading cancer sites.

What has Changed in Medicine Pricing?

The latest intervention focuses on non-scheduled medicines, which are not subject to the same ceiling-price mechanism as drugs included in the National List of Essential Medicines.
The Drugs (Prices Control) Order, 2013, gives the government the power to control medicine prices when necessary to protect public interest. It fixes maximum prices for scheduled medicines, while prices of non-scheduled medicines are generally monitored. Using this order, the government has now stepped in to limit the trade margins on the selected anti-cancer medicines.

Trade margins represent the difference between the price at which medicines are supplied through the distribution chain and the price at which they are sold to consumers. Excessive mark-ups can make medicines significantly more expensive before they reach patients. Under the new arrangement, the trade margin on the identified medicines has been capped at 30% of the MRP. The measure follows a similar exercise in 2019, when trade margins on 42 non-scheduled anti-cancer medicines were rationalised.

The revised prices cover medicines used in treating different cancers. These include Bevacizumab, used for lung, colon, ovarian and cervical cancers; Denosumab, used in breast and prostate cancer patients to prevent bone loss; and Pegfilgrastim, prescribed to prevent neutropenia in cancer patients.

The price changes are substantial for several brands. Zydus Lifesciences’ Bevacizumab brand Bryxta, for instance, has seen its MRP fall from 25,995 rupees to 3,318 rupees. Reliance Life Sciences’ Abiraterone acetate brand Abirone has declined from 41,250 rupees to 3,218 rupees. Similarly, the price of Reliance Life Sciences’ Peg-ReliGrast has fallen from 5,331 rupees to 1,258 rupees.

Cancer Drugs: Financial Burden of Cancer Care

The importance of reducing medicine prices becomes clearer when viewed against the financial burden of cancer treatment. A study published in Frontiers in Public Health in 2023, involving 12,148 cancer patients across seven treatment centres in India, estimated the average annual direct out-of-pocket expenditure on cancer treatment at 3.31 lakh rupees per patient. Medicines accounted for 45% of expenditure during hospitalisation, while diagnostics contributed 36.4% of outpatient treatment expenditure.

A patient receives medical care through an intravenous line at a hospital.
A patient with an intravenous line and pulse oximeter attached during hospital treatment, illustrating the cost of cancer care and the importance of affordable medicines. Representational image. Image credit: Tho-Ge/ Pexels

The findings illustrate why medicine affordability matters, particularly for patients who require repeated treatment. Even when the cost of a particular drug declines, expenses related to diagnostics, surgery, hospitalisation and travel can continue to weigh heavily on households.

What Happens Next?

The revised prices will apply to the identified medicines, including 10–15 drugs that have not yet been launched in India. Their prices will also be subject to the margin restrictions when they enter the market. Manufacturers can undertake annual price increases in accordance with the Drugs (Prices Control) Order, 2013, subject to continued compliance with the maximum permissible trade margin.

The NPPA has also directed retailers, dealers, hospitals and medical institutions to prominently display the revised MRP lists. State Drug Controllers will monitor compliance. Consumers can verify medicine prices through the Pharma Sahi Daam mobile application and the NPPA website. The reduction addresses an important component of cancer treatment expenditure: the price patients pay for medicines. Its impact, however, will depend on whether the revised prices are implemented consistently across pharmacies and hospitals, and whether patients can access the medicines they need.

Lower medicine prices can ease a substantial part of the financial burden. Making cancer treatment affordable, however, will also require attention to diagnostic costs, hospital charges and access to quality treatment across the public healthcare system.

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How Rubella Virus Finds Its Way Into the Placenta: Scientists Identify a Human Cell Receptor

A new Nature study identifies Nectin-4 as a receptor that helps the rubella virus enter placental and respiratory cells, offering insight into congenital rubella syndrome.

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Blue rubella virus particles interacting with red human placental cells, illustrating viral entry into placental tissue.
A scientific illustration showing rubella virus particles near human placental cells. Researchers have identified Nectin-4 as a receptor that facilitates viral entry into placental tissue. Representational image. Image credit: CDC/ Pexels

An infection that causes little more than a rash and mild fever in many people can have devastating consequences when it occurs during pregnancy. Rubella, a contagious viral disease, can cross the maternal–foetal interface and interfere with the development of an unborn child, causing hearing loss, heart defects, cataracts and other complications collectively known as congenital rubella syndrome (CRS).

An estimated 26,859 children were born with congenital rubella syndrome worldwide in 2024, according to a modelling analysis published by the US Centers for Disease Control and Prevention (CDC) in July 2026. Although this represents a substantial decline from an estimated 101,381 cases in 2012, the disease continues to affect newborns in countries where vaccination coverage remains inadequate. But how does the rubella virus enter the cells lining the respiratory tract and the placenta?

A study published in Nature identifies a protein called Nectin-4 as one of the cellular entry points used by the virus. The finding offers a closer look at how rubella establishes infection in two tissues central to its transmission and its effects during pregnancy.

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A newborn baby in a hospital cot. Congenital rubella syndrome can cause hearing impairment, congenital heart defects, cataracts and other developmental complications following rubella infection during pregnancy. Representational image. Image credit: Kevin Sparling/ Pexels

Protein That Opens the Door

Like other viruses, rubella cannot reproduce on its own. It must enter a living cell and use its machinery to produce new viral particles. This often begins when proteins on the virus’s outer envelope bind to specific molecules on the surface of a human cell. These molecules, called receptors, determine which cells a virus can enter. Identifying them helps researchers understand why certain tissues are vulnerable to infection.

The research team found that rubella uses Nectin-4, a cell-adhesion protein, to gain entry into respiratory and placental cells. Nectin-4 normally helps neighbouring cells maintain contact with one another and is present in several human tissues. The virus carries two envelope proteins, E1 and E2, which participate in its interaction with host cells. The researchers found that this viral protein complex interacts directly with Nectin-4. Once the proteins bind, the cell draws the virus inside through a process called receptor-mediated endocytosis, in which a section of the cell membrane folds around an external particle.

To establish the receptor’s role, the team combined protein-interaction analysis with CRISPR-Cas9 screening. They found that cells that were initially resistant to rubella infection became susceptible after Nectin-4 was introduced. Removing or blocking the protein, meanwhile, reduced infection. This offered evidence that Nectin-4 is involved in the virus’s entry into human cells, rather than simply being present alongside the infection.

What Happens at the Maternal–foetal Interface?

The finding has particular relevance to the placenta, the organ through which oxygen and nutrients pass from the mother to the developing foetus. During pregnancy, rubella can infect placental tissue and subsequently reach the foetus. The risk of serious complications is highest during early pregnancy, when the organs are developing. An infection during this period can result in miscarriage, stillbirth or congenital abnormalities.

The researchers examined syncytiotrophoblasts, specialised cells that form the outermost layer of the placenta and come into direct contact with maternal blood. These cells constitute an important part of the barrier between maternal circulation and the developing foetus.

Their experiments showed that Nectin-4 is abundantly expressed in these cells and facilitates rubella infection. When the researchers blocked the receptor, infection in laboratory models of placental tissue declined. The result helps explain how the virus can establish an infection at the maternal–foetal interface. It also identifies a specific cellular interaction that researchers can investigate when studying the transmission of rubella during pregnancy.

There is, however, an important limitation. The team found that rubella could also infect other placental cell populations through pathways that do not depend on Nectin-4. Blocking this single receptor may therefore be insufficient to prevent the virus from infecting the entire placenta.

A Shared Entry Route With Measles

The research also sheds light on rubella infection in the respiratory tract, where the virus initially establishes itself after entering the body. Using laboratory models of human airway tissue, the researchers found that Nectin-4 facilitates viral entry through the basolateral surface of respiratory epithelial cells, which faces the underlying tissue. After entering and replicating within these cells, newly produced viral particles are released from the opposite, airway-facing surface.

This arrangement offers a possible explanation for how rubella infects respiratory tissue and releases viral particles into the airways. Nectin-4 is also recognised as a cellular receptor for the measles virus. The finding that both viruses use the same human protein is an interesting connection, although the two infections involve different molecular interactions and should not be assumed to follow identical pathways.

Could Blocking the Receptor Prevent Infection?

The discovery raises the possibility of developing antiviral treatments that interfere with the interaction between rubella and Nectin-4. A molecule capable of preventing the viral envelope proteins from binding to the receptor could potentially restrict the virus’s entry into susceptible cells. The researchers’ experiments, in which blocking Nectin-4 reduced infection, offer an initial basis for investigating this approach.

For congenital rubella syndrome, the potential application is particularly relevant. Preventing the virus from establishing an infection in placental tissue could eventually help researchers explore ways of reducing the risk of foetal infection.

Such an application remains a research possibility, however. The experiments were conducted using laboratory cell and tissue models; they do not establish that receptor-blocking treatments can prevent congenital rubella syndrome in pregnant women. The alternative routes of placental infection identified by the researchers also present a challenge for any treatment targeting Nectin-4 alone.

Vaccination Remains Central to Prevention

The findings come at a time when rubella vaccination has substantially reduced the global burden of infection, although elimination remains uneven across countries. The CDC recorded 31,593 reported rubella cases worldwide in 2024. This figure reflects infections detected and reported through national surveillance systems, rather than the full number of people infected. The WHO, meanwhile, estimates that around 100,000 infants are born with congenital rubella syndrome annually, using a broader global estimate. These figures come from different reporting and estimation approaches and should not be treated as directly comparable.

By 2024, 179 of 194 countries had introduced rubella-containing vaccines into their routine immunisation programmes, according to the CDC. Global coverage with the first dose rose from 39% in 2012 to 73% in 2024. India includes measles-rubella vaccination in its Universal Immunisation Programme, with two routine doses recommended during childhood. Sustaining coverage is important because rubella infection in an unvaccinated pregnant woman can have consequences that extend well beyond the period of the initial illness.

For now, the identification of Nectin-4 does not change how rubella is prevented or treated. Its importance lies in revealing a previously insufficiently understood interaction between the virus and human cells. Researchers now have a specific receptor to investigate as they work towards understanding how rubella reaches placental tissue and whether that process can eventually be interrupted.

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AI-assisted telemedicine improves healthcare access in rural Rajasthan, study finds

A study from rural Rajasthan highlights how AI-assisted telemedicine, portable diagnostic tools and remote consultations could help extend healthcare access in underserved communities. The findings point to the potential of technology-supported care while underscoring the need for clinical oversight and further evaluation.

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Medical professionals are increasingly exploring AI-assisted tools to support clinical decision-making and diagnostic services.Image credit: Pexels

Study involving 10 villages highlights the potential of AI-supported consultations to address rural healthcare gaps, but connectivity and clinical validation remain challenges.

An artificial intelligence (AI)-assisted telemedicine model combining frontline health workers, portable diagnostic devices and remote medical consultations was associated with improved access to healthcare in hard-to-reach villages of Rajasthan, according to a study published in Preventive Medicine Reports in November 2026.

The community-based study, conducted across 10 villages in Balotra district between March 2024 and January 2026, evaluated whether technology-supported consultations could help overcome geographical and infrastructural barriers to healthcare. Researchers compared five intervention villages using assisted telemedicine with five comparison villages where residents followed conventional healthcare-seeking pathways.

During the 10-month intervention period, all 4,401 recorded symptomatic illness episodes in the intervention villages received teleconsultations. In comparison villages, only 1,528 of 3,973 recorded illness episodes (38.5%) resulted in visits to formal healthcare facilities.

The researchers attributed the difference to barriers including long travel distances, transportation difficulties, time constraints and reliance on self-medication or home remedies. However, the study was non-randomised, and the two groups used different methods of recording healthcare utilisation. The findings therefore demonstrate an association with improved access rather than definitive proof that the intervention caused the difference.

How AI supports remote consultations

Under the model, trained frontline health workers, including Accredited Social Health Activists (ASHAs) and Auxiliary Nurse Midwives (ANMs), visited households to identify people requiring medical attention. They recorded symptoms and collected vital signs using portable diagnostic equipment, including digital blood pressure monitors, pulse oximeters, thermometers and electrocardiographs (ECGs).

The information was transmitted through a telemedicine platform to remotely stationed doctors. An AI-supported clinical decision support system analysed the symptoms and diagnostic information to generate probable diagnoses, clinical advice and medication suggestions. Doctors reviewed the recommendations and retained responsibility for clinical decisions.

Of the 4,401 teleconsultation records, 98.6% were managed without referral to higher healthcare facilities. Respiratory conditions accounted for 24.2% of consultations. Portable ECG examinations also identified abnormalities in 21.6% of the 74 patients presenting with cardiovascular symptoms who underwent testing.

The researchers highlighted the role of frontline health workers in facilitating consultations and building trust among rural residents. However, technical disruptions and connectivity problems remained challenges during implementation.

Supporting evidence from recent research

The Rajasthan findings come alongside growing research into the use of AI in primary healthcare. A separate study published in the International Journal of Telemedicine and Applications on October 28, 2026, examined the technical performance of an AI-assisted clinical decision support system developed for rural telemedicine services.

Researchers from the ICMR-National Institute of Health Research, Jodhpur, and IIT Jodhpur evaluated the TeleMed Clinical Decision Support System (CDSS v2.5), which uses machine-learning models to interpret symptoms, identify probable diagnostic categories and support physicians during consultations.

Using five-fold cross-validation on 4,401 patient records, the system achieved an accuracy of 87.2% and a macro area under the receiver operating characteristic curve (AUROC) of 0.962. The system also incorporated a doctor-in-the-loop mechanism through which clinicians could review and modify AI-generated recommendations.

However, the researchers clarified that the results represent internal technical validation rather than independent evidence of clinical effectiveness. External validation and prospective studies are needed before wider deployment. The evaluation also used the same 4,401-record dataset associated with the Rajasthan telemedicine programme, rather than an independent patient population.

A 2026 systematic review and meta-analysis published in Frontiers in Digital Health provides broader evidence. It examined 13 randomised controlled trials involving more than 29,000 participants to assess the integration of AI and telemedicine into primary and family healthcare.

The review found that AI applications improved diagnostic accuracy and clinical decision-making across the included studies. Telemedicine interventions also showed favourable effects on healthcare access, chronic disease management and patient satisfaction, although the pooled clinical effect across 10 trials did not reach statistical significance.

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telemedicine

Representative image.Image credit:Pexels

The researchers identified reliable digital infrastructure, healthcare-worker training and integration into existing clinical workflows as important conditions for successful adoption. Connectivity limitations, patient digital literacy, privacy concerns and interoperability between systems were among the barriers.

Scaling digital healthcare requires safeguards

India’s experience with telemedicine also offers a broader context for the findings. A study published in Oxford Open Digital Health in October 2025 examined the adoption of eSanjeevani, the country’s government-led telemedicine service. Analysing programme data from November 2019 to September 2023, researchers recorded more than 163 million consultations across 28 states and eight Union Territories. The provider-assisted model accounted for over 93% of usage, demonstrating the importance of frontline healthcare workers in delivering digital services.

While telemedicine can reduce travel and improve access to doctors, the integration of AI introduces additional concerns relating to diagnostic errors, data privacy and accountability. The World Health Organization has cautioned that AI systems can generate inaccurate or biased recommendations and that healthcare professionals should not rely on automated outputs without appropriate oversight.

The Rajasthan study also acknowledged limitations, including the absence of direct patient health outcomes and systematic assessments of adverse recommendations or diagnostic errors.

As India expands its digital healthcare infrastructure, the findings highlight the potential of combining human medical expertise with AI-supported tools to reach underserved populations. However, improving connectivity, strengthening healthcare-worker training and establishing independent clinical validation will be essential to ensure that technological expansion translates into safer and more equitable healthcare.

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