@phdthesis{oai:nagasaki-u.repo.nii.ac.jp:00001094,
 author = {MINH, HUONG  PHU LY},
 month = {Mar},
 note = {Background: Antibodies are critical responses to protect the host from dengue virus(DENV) infection. Antibodies target DENV by two pathologic mechanisms: virus neutralization and infection enhancement. In dengue patients, the absence of neutralizing activity in the presence of FcγR implies that infection-enhancing activity hampers the neutralizing activity of antibodies, which could potentially lead to symptomatic presentations and severe clinical outcomes. Methods: A total of 100 pair serum samples from adult healthy volunteers were obtained during the dengue season in Ha Noi in 2015 for evaluation of neutralizing and infection-enhancing activity. Additionally, 20 serum samples from acute secondary DENV infection patients were also used as the patient group in this study. PRNT was performed on BHK cells and FcγR-expressing BHK cell lines for all serum samples. Results: Out of 100 residents, positive neutralizing antibodies (N.A) were found in 44.23 and 76.92% for DENV-1; 38.46 and 75% for DENV-2; 19.23 and 15.38% for DENV-3; and 1.92 and 9.62% for DENV-4 for pre and post-dengue season respectively. The percentage of post-exposure residents having positive responses against single, two, or more than three DENV serotypes were 38.46, 44.23 and 15.38%, respectively. A total of 34 residents were DENV seropositive before the dengue season and these individuals demonstrated further elevation of IgG antibodies after the dengue season. At the end of the season, 18 residents were confirmed to be new asymptomatic DENV infection cases. In both groups, N.A titers determined on BHK cells were higher than that on FcγR-expressing BHK cells. In heterotypic N.A responses, N.A titers to the infecting serotype from the samples obtained from pre-exposure group were significantly higher than those of the patient group. However, fold enhancement to the infecting serotypes from the samples in the pre-exposure group was substantially lower as compared to that of the patient group. Conclusion: Before and after the dengue season, serum samples from healthy volunteers demonstrated high levels of neutralizing antibodies and low or absence of infection-enhancement activity. The results suggest that while infection-enhancement activity hampers neutralizing activity of antibodies, high levels of DENV neutralizing antibodies set a critical threshold in facilitating the prevention of disease progression., 長崎大学学位論文 学位記番号:博(医歯薬)甲第1058号 学位授与年月日:平成30年3月20日, Author: Minh Huong Phu Ly, Meng Ling MoiEmail author, Thi Bich Hau Vu, Mya Myat Ngwe Tun, Todd Saunders, Cam Nhat Nguyen, Anh Kieu Thi Nguyen, Hung Manh Nguyen, Than Huu Dao, Do Quyen Pham, Thi Thu Thuy Nguyen, Thi Quynh Mai Le, Futoshi Hasebe and Kouichi Morita, Citation: BMC Infectious Diseases, 18, 31; 2018, Nagasaki University (長崎大学), 博士(医学) (2018-03-20)},
 school = {Nagasaki University (長崎大学)},
 title = {Dengue virus infection-enhancement activity in neutralizing antibodies of healthy adults before dengue season as determined by using FcγR-expressing cells},
 year = {2018}
}