PRELIMS REVISION QUIZ (DAY-07)

There are two main types of lymphocytes : B-cells and T-cells.

1⃣ B-CELLS : The B-cells produce antibodies that are used to attack invading bacteria, viruses and toxins.

2⃣ T-CELLS : The T-cells destroy the body's own cells that have themselves been taken over by viruses or become cancerous.

VIRAL VECTORS USED IN GENE-THERAPY

The most common gene therapy vectors are viruses because they can recognize certain cells and carry genetic material into the cells' genes.

Researchers remove the original disease-causing genes from the viruses, replacing them with the genes needed to stop disease.

Some of the viruses currently used in gene therapy include retroviruses, adenoviruses, adeno-associated viruses and the herpes simplex virus.

THE SCIENCE BEHIND MOST PROMISING COVID VACCINES

Covid vaccines use something called "ADENOVIRUS". What is that and why is it used?

Adenoviruses are viruses that can cause the common cold.

We as humans have them, monkeys have them, so do other animals.

For covid-19 vaccine, researchers swap a gene of adenovirus with a gene from coronavirus SARS-CoV-2.

When the vaccine is given to someone, the modified cold virus makes SARS-CoV2 spike protein, which stimulates the immune response.

VIRIONS

When not infecting/replicating inside a living cell, viruses exist in the form of independent particles called Virions.

A virion is an entire virus particle consisting of an outer protein shell called a capsid and an inner core of nucleic acid (either RNA or DNA).

The core confers infectivity, and the capsid provides specificity to the virus.

Viruses are capable of infecting any living thing – from prokaryotes bacteria and archaea to eukaryotes such as plants, animals and fungi.

Viruses cannot infect dead organic matter, because they are parasitic entities which need a living host cell to grow, metabolize and reproduce.

Viruses can also infect other viruses.

VIROPHAGES – VIRUSES WHICH INFECT OTHER VIRUSES

Viruses are not considered as alive, because they cannot reproduce on their own like bacteria or multicellular organisms.

But some giant viruses, like mimivirus, seem to blur the line between alive and dead—Giant viruses seem to have more similarities with living bacteria than with a common influenza virus.

Giant viruses are almost as large as bacteria and their genomes have many of the genes necessary for replication.

Just like bacteria can be infected by specialized viruses called bacteriophages, giant viruses can also be infected by specialized viruses called virophages.