Publications by authors named "Meenakshi Kar"

Article Synopsis
  • Recent vaccination and natural infections have led to a significant drop in severe cases, hospitalizations, and deaths from SARS-CoV-2, despite the emergence of new variants that can evade some immune defenses.
  • Research involving mice showed that they remained protected against a closely related ancestral virus, even with low neutralizing antibodies after exposure to newer variants, suggesting a strong immune response lasting from prior infections.
  • The study highlighted the importance of T cells in providing this protection, as previous infection resulted in higher levels of tissue-resident memory T cells in the nasal area, though less prominent in the lungs.
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Waning immunity and the emergence of immune evasive SARS-CoV-2 variants jeopardize vaccine efficacy leading to breakthrough infections. We have previously shown that innate immune cells play a critical role in controlling SARS-CoV-2. To investigate the innate immune response during breakthrough infections, we modeled breakthrough infections by challenging low-dose vaccinated mice with a vaccine-mismatched SARS-CoV-2 Beta variant.

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SARS-CoV-2 infection induces the generation of virus-specific CD4 and CD8 effector and memory T cells. However, the contribution of T cells in controlling SARS-CoV-2 during infection is not well understood. Following infection of C57BL/6 mice, SARS-CoV-2-specific CD4 and CD8 T cells are recruited to the respiratory tract, and a vast proportion secrete the cytotoxic molecule granzyme B.

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Article Synopsis
  • SARS-CoV-2, the virus causing COVID-19, triggers the quick production of T cells in the body, which help in fighting the infection and forming a memory against it.
  • A study using mice showed that while T cells are recruited to the respiratory tract, they have different roles in the upper (nose) and lower (lungs) parts; specifically, they are less crucial for clearing the virus from the lungs.
  • The research found that both CD4+ and CD8+ T cells are essential for controlling viral replication in the nasal region, suggesting that T cells play a significant role in managing the infection within the respiratory tract.
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Zinc-dependent viral proteins rely on intracellular zinc homeostasis for successful completion of infectious life-cycle. Here, we report that the intracellular labile zinc levels were elevated at early stages of dengue virus (DENV) infection in hepatic cells and this increase in free zinc was abolished in cells infected with UV-inactivated virus or with a DENV replication inhibitor implicating a role for zinc homeostasis in viral RNA replication. This change in free zinc was mediated by zinc transporter, ZIP8, as siRNA-mediated knockdown of ZIP8 resulted in abrogation of increase in free zinc levels leading to significant reduction in DENV titers suggesting a crucial role for ZIP8 in early stages of DENV replication.

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Reactive oxygen species (ROS) are chemically active species which are involved in maintaining cellular and signalling processes at physiological concentrations. Therefore, cellular components that regulate redox balance are likely to play a crucial role in viral life-cycle either as promoters of viral replication or with antiviral functions. Zinc is an essential micronutrient associated with anti-oxidative systems and helps in maintaining a balanced cellular redox state.

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Zinc is an essential micronutrient which regulates diverse physiological functions and has been shown to play a crucial role in viral infections. Zinc has a necessary role in the replication of many viruses, however, antiviral action of zinc has also been demonstrated in infection models most likely through induction of host antiviral responses. Therefore, depending on the host machinery that the virus employs at different stages of infection, zinc may either facilitate, or inhibit virus infection.

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Objective: To characterize the in vitro replication fitness, viral diversity, and phylogeny of dengue viruses (DENV) isolated from Indian patients.

Methods: DENV was isolated from whole blood collected from patients by passaging in cell culture. Passage 3 viruses were used for growth kinetics in C6/36 mosquito cells.

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Thrombocytopenia is a characteristic feature during the acute phase of dengue infection and has been found to associate with vascular leakage in severe dengue. Although dengue antigens have been observed in platelets, there is no strong evidence to suggest a direct infection of platelets by dengue virus as a contributing factor for thrombocytopenia. We show that dengue virus can enter platelets but replicate viral ribonucleic acid to a minimal extent and, therefore, cannot produce infectious virus.

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Around 10,000 people die each year due to severe dengue disease, and two-thirds of the world population lives in a region where dengue disease is endemic. There has been remarkable progress in dengue virus vaccine development; however, there are no licensed antivirals for dengue disease, and none appear to be in clinical trials. We took the approach of repositioning approved drugs for anti-dengue virus activity by screening a library of pharmacologically active compounds.

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Dengue virus, a mosquito-borne flavivirus, is a causative agent for dengue infection, which manifests with symptoms ranging from mild fever to fatal dengue shock syndrome. The presence of four serotypes, against which immune cross-protection is short-lived and serotype cross-reactive antibodies that might enhance infection, pose a challenge to further investigate the role of virus and immune response in pathogenesis. We evaluated the viral and immunological factors that correlate with severe dengue disease in a cohort of pediatric dengue patients in New Delhi.

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Background: GLUTs are a family of proteins that mediate glucose transport through the membrane, expressed in head and neck squamous cell carcinoma. GLUT-1 positivity in malignant cells indicates increased proliferative activity, energy requirements, aggressive behaviour and poor radiation response.

Aim: To observe the expression of GLUT-1 protein in oral squamous cell carcinoma in tobacco and non-tobacco users and to correlate the expression with histopathological grading and pathological staging.

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