Which of the following is commonly used as a vector for introducing a DNA fragment in human lymphocytes?
(a) Retrovirus
(b) Ti plasmid
(c) l phage
(d) pBR322
Answer (a) : Retroviruses cause cancer in animals including humans. So modified retroviruses are used to transfer desirable genes into animal cells. It is used in gene therapy, in which lymphocytes from blood of patient are grown in culture medium outside the body, a functional gene is introduced by using a retroviral vector into these lymphocytes.
