Immune System Overview

macrophages, neutrophils, and dendritic cells

phagocytosis

phagosome

chemotaxis

skin, nose, lungs, stomach, and intestines

enzymes, complement proteins, and cytokines

50% to 60%

serve as a link between the bodily tissues and the innate and adaptive immune systems

The innate immune system and the adaptive immune system.

It provides a preconfigured response to broad groups of situations and stimuli.

It provides a tailored response by learning to recognize molecules it has previously encountered.

Phagocytosis, antimicrobial peptides called defensins, and the complement system.

The process of acquired immunity, which creates an immunological memory leading to an enhanced response to subsequent encounters with the same pathogen.

Autoimmune diseases, inflammatory diseases, and cancer.

Immunodeficiency occurs when the immune system is less active than normal, resulting in recurring and life-threatening infections.

Causes of immunodeficiency include genetic diseases, acquired conditions, or immunosuppressive medication.

Autoimmunity is a condition where the immune system attacks normal tissues as if they were foreign organisms.

Hashimoto's thyroiditis, rheumatoid arthritis

Physical barriers, innate immune system, and adaptive immune system.

Toll-like receptors (TLRs), NOD-like receptors, RIG-like receptors, and cytosolic DNA sensors.

Most plant viruses are rod-shaped, with protein discs forming a tube surrounding the viral genome; isometric particles are another common structure.

The great majority of plant viruses have an RNA genome, which is usually small and single stranded (ss), but some viruses have double-stranded (ds) RNA, ssDNA or dsDNA genomes.

Tobacco mosaic virus (TMV) is well-known as it was the first virus to be discovered.

Plant viruses cause an estimated US$60 billion loss in crop yields worldwide each year.

To transmit from one plant to another, plant viruses usually involve vectors, such as insects, as most plants do not move.

Plant viruses are grouped into 73 genera and 49 families, but these figures relate only to cultivated plants, which represent only a tiny fraction of the total number of plant species.

The bridging hypothesis proposes that in non-persistent and semi-persistent viruses, the helper component binds to the specific domain of the coat protein, creating a bridge that aids in insect-mediated viral transmission.

Persistent propagative viruses, such as TSWV, have a lipid coat surrounding the proteins that is not seen in other classes of plant viruses. It has been proposed that these viruses bind via these proteins and are then taken into the insect cell by receptor-mediated endocytosis.

Soil-borne nematodes acquire and transmit viruses by feeding on infected roots. The virions attach to the stylet (feeding organ) or to the gut when they feed on an infected plant and can then detach during later feeding to infect other plants.

Plasmodiophorids are soil borne zoosporic protozoa that are not phytopathogenic themselves, but parasitic. They transmit a number of virus genera, both persistently and non-persistently, by becoming associated with the plant roots. They also create wounds in the plant's root through which other viruses can enter.

About 20% of plant viruses can be transmitted from generation to generation.

When viruses are transmitted by seeds, the seed is infected in the generative cells and the virus is maintained in the germ cells and sometimes, but less often, in the seed coat.

Examples of viruses that can be transmitted by nematodes include tobacco ringspot virus and tobacco rattle virus.

Examples of viruses transmitted by plasmodiophorids include Polymyxa graminis, which transmits plant viral diseases in cereal crops, and Polymyxa betae, which transmits Beet necrotic yellow vein virus.

Martinus Beijerinck coined the term 'virus' in the late 19th century.

Plants employ siRNA response to dsRNA as a defense against viral infection.

The RNA of Tobacco Mosaic Virus (TMV) was identified as the infectious material in the 1950s.

Rod-shaped plant viruses are over 50% in length between 300-500 nm and in diameters of 15-20 nm.

Transmission of plant viruses can occur through sap or insect vectors.

Rhabdoviruses have been proposed to be insect viruses that replicate in plants, and their chosen insect vectors determine their host range.