The aim of this study was to obtain fundamental data in animal experiments for KSHV vaccine development. To estimate immune responses against KSHV in animals, Balb/c mice were immunized click here intranasally or intraperitoneally with KSHV particles, and their immunoreactions were investigated. In addition, an in vitro neutralization assay was performed using green fluorescent protein-expressing recombinant KSHV and the serum, nasal wash fluid (NW), and saliva from the KSHV-immunized mice. KSHV particles were prepared from BCBL-1 cells stimulated with phorbol 12-myristate-13 acetate (PMA; Sigma, St. Louis, MO) as described previously [26]. Briefly, BCBL-1

cells were stimulated with PMA at 20 ng/mL for 72 h. The supernatant of

BCBL-1 cells was collected and filtered through a 0.8-μm-pored membrane. Filtered supernatant was ultracentrifuged at 20,000 × g for 2 h. The pellet was dissolved in one-fiftieth volume of RPMI 1640. Virus copy number was measured with a real-time PCR as described previously [27]. A green and red fluorescent protein (GFP/RFP)-expressing recombinant KSHV, rKSHV.219 (kindly provided by Dr. Jeffrey Vieira, Washington University), was collected for the neutralization assay as described previously [28]. Female 8-week-old Balb/c mice were purchased from Clea Japan (Tokyo, Japan) and were kept under specific-pathogen-free conditions. All animal experiments were performed in accordance selleckchem with the Guidelines for Animal Experiments Performed at the National Institute of Infectious Diseases (NIID) and were approved by the Animal Care and Use Committee of NIID (approvals No. 108056 and 209072). Five mice for each experimental group were anesthetized with isoflurane and immunized primarily by dropping 5 μl of phosphate buffered saline (PBS) containing

106–108 copies of KSHV or 10 ng of KSHV-encoded proteins with 10 μg of poly(I:C) (Sigma) into each nostril [29]. For immunization to the peritoneal cavity, 100-μl aliquots of PBS containing the viruses whatever (106–108 copies) or proteins (100 ng) with poly(I:C) were immunized to the mice’s peritoneal cavities. Additional immunizations were performed twice, 2 and 3 weeks later. Samples of blood, spleen, and NW were obtained from mice that were sacrificed under anesthesia with isoflurane 1 week after the final immunization. NW samples were taken as previously described [17]. Saliva samples were obtained using intraperitoneal administration of pilocarpine (150 μL of 1 mg/ml in PBS per mouse, P-6503, Sigma). Copy numbers of mouse IFN-γ, CD8 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA were determined with real-time RT-PCR using probe-primer sets described previously [30]. Total RNA was extracted from 1 × 107 spleen cells of each mouse with Isogen RNA isolation kit (Nippon Gene, Toyama, Japan). Real-time RT-PCR was performed with one-step Quantitect probe RT-PCR kit (Qiagen, Hilden, Germany).