Microbiology and Immunology

WORLD OF MICROBIOLOGY AND IMMUNOLOGY Plasmodium

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cient plasmids to be produced. Last, plasmids should have

selectable markers, such as antibiotics metabolite genes,

which allow the identification of the transformed bacteria.

Numerous plasmid vectors have been developed since the

first plasmid vectors of the early 1970s. Some vectors have

bacteriophagepromoter sequences flanking the MSC that

allows direct sequencing of the cloned DNA sequence. Some

vectors have yeast or virus replicationorigin, which allows

the plasmids to replicate in yeast and mammalian cells, hence

enabling cloned cDNAs to express in these host cells. Many

new features have and will be added into plasmids to make

genetic engineering easier and faster.

See alsoCloning, application of cloning to biological prob-

lems; DNA (Deoxyribonucleic acid); DNA hybridization;

Molecular biology and molecular genetics

PPlasmodiumLASMODIUM

Plasmodiumis a genus of protozoathat has a life cycle that

includes a human host and a mosquito. The genus consists pre-

dominantly of four species: Plasmodium falciparum,

Plasmodium vivax, Plasmodium ovale, and Plasmodium

malariae. With the exception of the latter species,

Plasmodiumare parasitesof humans.

The main disease of concern with Plasmodium is

malaria. This disease has been a problem for humans for mil-

lennia. There are still almost 20 million cases of malaria

reported each year. The number of people who are actually

infected is thought to be upwards of 500 million people annu-

ally. The death toll from malaria is one to two million people

each year, mostly in underdeveloped countries. But even in

developed countries, malaria can be a problem, especially if

mosquito control programs are not vigilant.

The protozoan is spread to humans by the bite of a

female Anopheline mosquito. A form of the parasite known as

Transmission electron micrograph of plasmids.

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