( ( ( ( ( ( The laboratory ) ( uses ( ( a combination ) ( of ( ( ( genetic manipulations ) , ) ( molecular biology ) ) ) ) ) ) , ) and ) ( animals ( studies ( ( ( to ( identify ( ( the function ) ( of ( these ( two ( viral ( gene products ) ) ) ) ) ) ) ) and ) ( to ( identify ( ( other ( viral genes ) ) ( which ( regulate ( cell tropism ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT The) (NN laboratory)) (VP (VBZ uses) (NP (NP (DT a) (NN combination)) (PP (IN of) (NP (NP (JJ genetic) (NNS manipulations)) (, ,) (NP (JJ molecular) (NN biology))))))) (, ,) (CC and) (S (NP (NNS animals)) (VP (VBZ studies) (S (VP (VP (TO to) (VP (VB identify) (NP (NP (DT the) (NN function)) (PP (IN of) (NP (DT these) (CD two) (JJ viral) (NN gene) (NNS products)))))) (CC and) (VP (TO to) (VP (VB identify) (NP (NP (JJ other) (JJ viral) (NNS genes)) (SBAR (WHNP (WDT which)) (S (VP (VB regulate) (NP (NN cell) (NN tropism)))))))))))) (. .)))
The laboratory uses a combination of genetic manipulations, molecular  biology, and animals studies to identify the function of these two viral gene products and to identify other viral genes which regulate cell tropism.
(ROOT (S (NP (DT A) (JJ viral) (NN vector)) (VP (VBZ is) (NP (NP (DT the) (NN name)) (PP (IN for) (NP (NP (DT a) (NN tool)) (VP (ADVP (RB commonly)) (VBN used) (PP (IN by) (NP (JJ molecular) (NNS biologists))) (S (VP (TO to) (VP (VB place) (NP (JJ genetic) (NN material)) (PP (IN into) (NP (NNS cells))))))))))) (. .)))
A viral vector is the name for a tool commonly used by molecular biologists to place genetic material into cells.