Необходимые свойства векторов

Необходимые элементы любого молекулярного вектора.

Молекулярный вектор должен обладать:

(1) участком, определяющей начало репликации;

(2) сайтом для встройки чужеродной ДНК;

(3) селективным маркером.

In molecular biology, a vector is a DNA molecule used as a vehicle to transfer foreign genetic material into another cell. The four major types of vectors are plasmids, viral vectors, cosmids, and artificial chromosomes. Common to all engineered vectors are (1) an origin of replication, (2) a multicloning site, and (3) a selectable marker. A multiple cloning site (MCS), also called a polylinker, is a short segment of DNA which contains many (up to ~20) restriction sites - a standard feature of engineered plasmids. MCSs let a biologist insert a piece of DNA or several pieces of DNA into the region of the MCS.

Необходимые свойства клонирующих векторов:

(1) вектор должен нести нуклеотидную последовательность (или последовательности), которые отвечает за автономную репликацию данной молекулы в определенном типе клеток;

(2) не должен терять репликативных свойств даже при встройке чужеродного фрагмента ДНК;

(3) должен иметь как можно малое число мест расщепления определенной рестриктазой, лучше один сайт, или локус рестрикции;

(4) должен содержать 1 или несколько генетических маркеров, по которому может быть произведен отбор клонов; т.е. если вектор успешно внедрился в клетку (существует определенный процент успеха), эту клетку (или группу клеток) необходимо отобрать по хорошо различимому признаку и размножить, и таким путем произвести молекулярное клонирование;

(4) должен реплицироваться с образованием повышенного числа копий в клетке.

Необходимые свойства вирусного вектора. Key properties of a viral vector. Viral vectors are tailored to their specific applications but generally share a few key properties:

(1) Безопасность - Safety: Although viral vectors are occasionally created from pathogenic viruses, they are modified in such a way as to minimize the risk of handling them. This usually involves the deletion of a part of the viral genome critical for viral replication. Such a virus can efficiently infect cells but, once the infection has taken place, requires a helper virus to provide the missing proteins for production of new virions.

(2) Низкая патогенность - Low toxicity: The viral vector should have a minimal effect on the physiology of the cell it infects.

(3) Стабильность - Stability: Some viruses are genetically unstable and can rapidly rearrange their genomes. This is detrimental to predictability and reproducibility of the work conducted using a viral vector and is avoided in their design.

(4) Клеточная специфичность - Cell type specificity: Most viral vectors are engineered to infect as wide a range of cell types as possible. However, sometimes the opposite is preferred. The viral receptor can be modified to target the virus to a specific kind of cell. Viruses modified in this manner are said to be pseudotyped.

(5) Идентификация - Identification: Viral vectors are often given certain genes that help identify which cells took up the viral genes. These genes are called Markers, a common marker is antibiotic resistance to a certain antibiotic. The cells can then be isolated easily as those that have not taken up the viral vector genes do not have antibiotic resistance and so cannot grow in a culture with antibiotics present.