title: Immune responses following salivary gland administration of recombinant adeno-associated virus serotype 2 vectors.
abstract: BACKGROUND
  Gene transfer to salivary glands (SGs) can be accomplished in a minimally invasive manner, resulting in stable, long-term secretion of the transgene product. Therefore, SGs provide a novel target site for several potentially useful clinical gene therapeutics applications. Previous studies have indicated that intravenous, intramuscular and intranasal administration of recombinant adeno-associated virus serotype 2 (rAAV2) vectors induce host immune responses. There are no reported studies on immune responsiveness of rAAV2 vector administration to SGs.
  
  
  METHODS
  Vectors were administered by retrograde infusion to the SGs of Balb/c mice in various combinations. Thereafter, transgene expression was determined, and evaluations of host innate and adaptive immune responsiveness performed over a 56-day period.
  
  
  RESULTS
  Histological examination of SGs from vector-treated mice showed no significant changes in appearance from controls, including the frequency of activated macrophage detection. There were also no differences in salivary flow rates among experimental groups. In vitro stimulation of splenocytes from mice administered rAAV2 showed elevated interferon-gamma levels in culture media. Significant titers of neutralizing antibodies to rAAV2 were detected in serum of mice following rAAV2 vector administration. While SGs could be transduced with low doses of vector it was not possible to repeat the administration and detect transduction with the same serotype at low doses. However, repeat administration was possible with an alternative serotype (rAAV4).
  
  
  CONCLUSIONS
  Following a single administration of rAAV2 vectors to SGs there is no significant innate immune response. However, rAAV2 vector administration to SGs results in both cellular and humoral immune responses. The latter may interfere with the efficacy of repeated rAAV2 vector administration.
authors.affiliation: Gene Therapy and Therapeutics Branch, NIDCR, NIH, DHHS, Bethesda, MD, USA. m.r.kok@amc.uva.nl
authors.forename: Marc R
authors.initials: MR
authors.lastname: Kok
authors.forename: Antonis
authors.initials: A
authors.lastname: Voutetakis
authors.forename: Seiichi
authors.initials: S
authors.lastname: Yamano
authors.forename: Jianghua
authors.initials: J
authors.lastname: Wang
authors.forename: Ana
authors.initials: A
authors.lastname: Cotrim
authors.forename: Hisako
authors.initials: H
authors.lastname: Katano
authors.forename: Ioannis
authors.initials: I
authors.lastname: Bossis
authors.forename: John A
authors.initials: JA
authors.lastname: Chiorini
authors.forename: Simon D
authors.initials: SD
authors.lastname: Tran
authors.forename: Paul P
authors.initials: PP
authors.lastname: Tak
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Baum
mesh_terms: D000818:Animals; D002460:Cell Line; D000229:Dependovirus / Q000235:genetics*; D005822:Genetic Vectors / Q000008:administration & dosage; D006801:Humans; D007113:Immunity, Innate; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D016133:Polymerase Chain Reaction; D011995:Recombination, Genetic; D012469:Salivary Glands / Q000276:immunology*