>Top 7. Forecast from Viral Evolution:
- Definition of Species: a set of animals or plants in which the members have similar characteristics to each other and can breed with each other.
- Imanishi's Evolution theory expanded this definition to 'Specia', which means species society; not only individuals related by breeding, but include the partial society of living creatures.
- Species tend to be conservative to maintain the belonging species society.
- >Top Transfer of genes is not limited to the collection of reproductive individuals; it became clear that virus can transfer genes beyond species. (superspecia=the total species which can transfer genes via vertical and horizontal transfer)
- Eg. other animals except human and Japanese monkey cannot synthesize vitamin C in the body.
- The nature of virus is not to cause infectious diseases, but cause evolve species in superspecia.
- Plasmid of bacteria can transfer drug resistance gene to bacteria via its pilus, while virus is an intense organelle which can proliferates within the host cell, and can transfer genes beyond space and species. and space.
- All animals have various viruses, which assist to make the host animals evolve to a certain direction, in some cases drove the host to extinction.
- In some major extinction events occurred in the earth history, infectious diseases by viruses may be the real cause.
- Virus Evolution Theory:
- Neo-Darwinism attributes the change of genes to mutation.
- But Virus Evolution Theory consider it is caused by horizontal transfer of genes by a vector (plasmid and virus).
- Biotechnology proved to enable to make supermouse; which might have occurred in the case of giganticness of dinosaur.
- >Top ERV (Endogenous Retrovirus):
- about 12% of mammals' genome are derived from ERV. (Virus fossil); this shows the ancestor of mammals were infected by enormous retroviruses.
- Transposon: a segment of bacterial DNA that can transfer another place on the genome. (called jumping gene)
- Similarity of DNA between human and bacterium (Pseudomona K-62): mentioned below↓:
- Viral diseases will increase:
- highly contagious infectious disease by measles virus; causing fever, cough, runny nose, and inflamed eyes, red flat rash spreads on the body. No specific treatment is available, but supportive care only.
- The measles vaccine is effective to prevent the disease, and is delivered in combination with other vaccines. Vaccination resulted in 80% decrease in deaths now.
- infectious disease caused by two virus variants, variola major and variola minor. In 1980, WHO certified the global eradication of the disease. The risk of death was about 30%; with extensive scarring of skin, some were left blind.
- In 15-17C, Spanish delivered this disease from Old World to America during the conquest of Aztecs and Incas
- In 18C Europe, about 400K people died from the disease per year, killed up to 300M in 20C.
- 1796, Edward Jenner, pioneered to create smallpox vaccine. In Jenner's time, smallpox killed around 10% of population. He observed that milkmaids were generally immune to smallpox (cowpox).
- Yellow fever:
- This is common in tropical Africa and spread to South America.
- caused by yellow fever virus (RNA Flavvirus); symptoms include fever, chills, loss of appetite, nausea, muscle pains, then liver damage begins causing yellow skin. It infects only humans and other primates and several mosquitoes.
- A safe and effective vaccine exist. Without this vaccine, the construction of Panama canal could not be succeeded.
- Japanese encephalitis:
- This disease was first described in Japan in 1871, which is an infection of the brain caused by JEV; symptoms include headache, vomiting, fever, confusion and seizures, which occur 5-15 days after infection.
- JEV is generally spread by mosquitoes (specifically Culex type). Pigs and wild birds serve as a reservoir for the virus.
- prevention is with JE vaccine, which is safe and effective, as well as avoiding mosquito bites. Once infected, no specific treatment with only supportive care.
- Poliovirus: Infantile paralysis
- is a serotype of Entervirus C, composed of RNA genome having icosahedral symmetry, first isolated in 1909. Poliovirus is a simple and well-charactrized viruses, which become a model system to understand the biology of RNA viruses.
- is a highly infectious viral disease particularly under 5 years of age, and is transmitted by person-to-person spread, or by common vehicle (water or food) and multiplied in the intestines from where it can invade the nervous system and cause paralysis.
- Wild poliovirus cases have decreased by over 99% since 1988. US President Roosevelt was infected this disease and was forced to fight against illness.
- >Top Spanish flu:
- in 1918-20; caused by HiN1 influenza A virus; infested 500M people. The death was estimated 50M, or as high as 100M.
- It triggered a cytokine storm (immune system caused uncontrolled excessive release of signaling cytokines)
- Asian flu:
- in 1957-58; caused by influenza A virus subtype H2N2, originated in Gùizhōu, China, died 1-4M people.
- the virus was most deadly in pregnant women, elderly with pre-exisiting heart and lung disease.
- Recent cancer viruses, such as EB virus, Human papillomavirus (HPV), ATL virus, Ebolavirus, Human Immunodeficiency Virus (HIV) are continuously recognized.
- Disease-causing viruses are mutants or failures; their primary role is to deliver horizontally genes which cause evolution to the host.
- endogenous retrovirus (ERV): 内在性レトロウイルス
- LUCA: Last Universal Common Ancestor: 最終共通祖先
- Pseudomonas K-672: 水銀耐性菌
- mercuric reductase: 水銀還元酵素
- glutathione reductase: グルタチオン還元酵素
- Japanese enchephalitis (JE): 日本脳炎
- superinfection: 重複感染, second infection superimposed on an earlier one, following treatment with broad-spectrum antibiotics.
|Type of virus
|Herpes virus (HSV)
||salvary gland, kidney, lymphocyte
||lymphocyte (B cell)
||Herpes simplex virus
||Herpes zoster virus
||intestine, upper trachea
- 1918-20; 第一次大戦戦死者以上