( ( ( ( ( ( ( ( Some microbicides ) ( work ( by ( boosting ( ( the ( body 's ) ) ( natural ( defense systems ) ) ) ) ) ) ) , ) ( others ( ( ( ( introduce ( new substances ) ) ( to ( destroy pathogens ) ) ) or ) ( chemically ( ( block ( their entry ) ) ( into ( human cells ) ) ) ) ) ) ) , ) and ) ( still ( others ( create ( ( a type ) ( of ( physical barrier ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT Some) (NNS microbicides)) (VP (VBP work) (PP (IN by) (S (VP (VBG boosting) (NP (NP (DT the) (NN body) (POS 's)) (JJ natural) (NN defense) (NNS systems))))))) (, ,) (S (NP (NNS others)) (VP (VP (VB introduce) (NP (JJ new) (NNS substances)) (S (VP (TO to) (VP (VB destroy) (NP (NNS pathogens)))))) (CC or) (VP (ADVP (RB chemically)) (VB block) (NP (PRP$ their) (NN entry)) (PP (IN into) (NP (JJ human) (NNS cells)))))) (, ,) (CC and) (S (ADVP (RB still)) (NP (NNS others)) (VP (VBP create) (NP (NP (DT a) (NN type)) (PP (IN of) (NP (JJ physical) (NN barrier)))))) (. .)))
Some microbicides work by boosting the body's natural defense systems, others introduce new substances to destroy pathogens or chemically block their entry into human cells, and still others create a type of physical barrier.
(ROOT (S (NP (DT The) (JJ innate) (JJ immune) (NN system)) (VP (VBZ serves) (PP (IN as) (NP (NP (DT a) (JJ first) (NN responder)) (PP (TO to) (NP (NP (JJ pathogenic) (NNS threats)) (SBAR (WHNP (WDT that)) (S (VP (VB bypass) (NP (NP (JJ natural) (ADJP (NN physical) (CC and) (NN chemical)) (NNS barriers)) (PP (IN of) (NP (DT the) (NN body)))))))))))) (. .)))