Viruses SIDT2

Fall of neighborhood tree to construction of flyover in vicinity, all events are highly chaotic in nature. These changes will affect not only present living beings but all future generations.

Environmental threats have to be recorded. Viruses are the medium. Tran-generational threat-alert transfer.

Each organism does continuous environmental survey to keep the life in check. To protect the existence of living beings. To protect the well-being of all so that everyone can perform sva-dharma and contribute in universal sacrifice (यज्ञ).

What you do as human body, your body cells also perform at cellular level i.e. Random environmental survey.

I was reading chapter on viral infection (संक्रात्मक ज्वर) in children in one old book of Ayurveda.

Some of these fevers were given suffix ‘माता’.

For example, शीतला माता – known name.

What does ‘माता ‘ indicate?

Is it pro-life mandatory fever? Does this illness act as mother by enhancing life-long immunity?

Viral infection in children is a part of development cycle. There is no cure. Only better management of diet and routine can help to curb harmful effects. Such fevers (like seasonal fevers) act as mother (like how sometimes mother act tough to teach lesson)

Interesting research. It confirms two things.

  1. Life is a flow. Body is full of different transport channels. Viruses are messages.
  2. Viruses are for improving immunity. Immunity is your cellular intelligence to detect self from non-self.


‘Missing link’ explains how viruses trigger immunity

The research team demonstrated a protein called SIDT2 was crucial for cells to detect viral components in their environment, and initiate an immune response to reduce the virus’ spread.

During a viral infection, RNA – a genetic material similar to DNA – is released into the environment around the infected cells. Dr Nguyen said the team showed that SIDT2 allowed viral RNA to be shuttled between compartments within cells, allowing it to reach the proteins that trigger anti-viral immunity.

“This RNA is in a ‘double-stranded’ form, called ‘dsRNA’, that is not normally found in our body. Human cells have evolved ways to detect dsRNA as a warning sign of an active viral infection and, in this way, dsRNA acts as an important trigger for cells to mount an anti-viral immune response.

“Cells constantly survey their environment by ‘swallowing’ small samples of their environment into compartments called endosomes. The enigma was that no one knew how the dsRNA escaped the endosome to reach the cytoplasm, where it can be detected by the cell.” Dr Nguyen said.

The team showed that SIDT2 was the crucial missing link needed to transport dsRNA out of endosomes, and enable an immune response to be launched.

Viruses have many strategies to prevent an infected cell from alerting the immune system to their presence, Dr Pang said. “Intriguingly, we showed that SIDT2 is critical for uninfected ‘bystander’ cells to detect viral RNA in their environment,” Dr Pang said. “This means bystanders can trigger protective immunity before they even encounter the virus itself.

“Viruses have evolved many ways to switch off the immune response, allowing them to spread, while humans have evolved counter measures to allow a rapid and protective immune response that contains the viral infection. SIDT2 is helping humans in the ‘arms race’ between viruses and their human hosts.”

SIDT2 Transports Extracellular dsRNA into the Cytoplasm for Innate Immune Recognition

Double-stranded RNA (dsRNA) is a common by-product of viral infections and acts as a potent trigger of antiviral immunity. In the nematode C. eleganssid-1 encodes a dsRNA transporter that is highly conserved throughout animal evolution, but the physiological role of SID-1 and its orthologs remains unclear. Here, we show that the mammalian SID-1 ortholog, SIDT2, is required to transport internalized extracellular dsRNA from endocytic compartments into the cytoplasm for immune activation. Sidt2-deficient mice exposed to extracellular dsRNA, encephalomyocarditis virus (EMCV), and herpes simplex virus 1 (HSV-1) show impaired production of antiviral cytokines and—in the case of EMCV and HSV-1—reduced survival. Thus, SIDT2 has retained the dsRNA transport activity of its C. elegans ortholog, and this transport is important for antiviral immunity.

What is Endosome?

Structure and function of endosomes in plant cells

Endosomes are a heterogeneous collection of organelles that function in the sorting and delivery of internalized material from the cell surface and the transport of materials from the Golgi to the lysosome or vacuole. Plant endosomes have some unique features, with an organization distinct from that of yeast or animal cells. Two clearly defined endosomal compartments have been studied in plant cells, the trans-Golgi network (equivalent to the early endosome) and the multivesicular body (equivalent to the late endosome), with additional endosome types (recycling endosome, late prevacuolar compartment) also a possibility. A model has been proposed in which the trans-Golgi network matures into a multivesicular body, which then fuses with the vacuole to release its cargo. In addition to basic trafficking functions, endosomes in plant cells are known to function in maintenance of cell polarity by polar localization of hormone transporters and in signaling pathways after internalization of ligand-bound receptors. These signaling functions are exemplified by the BRI1 brassinosteroid hormone receptor and by receptors for pathogen elicitors that activate defense responses. After endocytosis of these receptors from the plasma membrane, endosomes act as a signaling platform, thus playing an essential role in plant growth, development and defense responses. Here we describe the key features of plant endosomes and their differences from those of other organisms and discuss the role of these organelles in cell polarity and signaling pathways.

Endosomes and Endocytosis

Endosomes are membrane-bound vesicles, formed via a complex family of processes collectively known as endocytosis, and found in the cytoplasm of virtually every animal cell. The basic mechanism of endocytosis is the reverse of what occurs during exocytosis or cellular secretion. It involves the invagination (folding inward) of a cell’s plasma membrane to surround macromolecules or other matter diffusing through the extracellular fluid. The encircled foreign materials are then brought into the cell, and following a pinching-off of the membrane (termed budding), are released to the cytoplasm in a sac-like vesicle. The size of vesicles varies, and those larger than 100 nanometers in diameter are typically referred to as vacuoles.