Notomi Sato1* Abstract Maternal LAMP/p55gagHIV-1 DNA Immunization Induces In Utero Priming and a Long-Lasting Immune Response in Vaccinated Neonates Paula Ordonhez Rigato1, Milton Maciel Jr2, Adriana Letı´cia Goldoni1, Orlando Guerra Piubelli1, Noemia Mie Orii1, Ernesto Torres Marques3, Joseph Thomas August4, Alberto Jose´ da Silva Duarte1, Maria 1 Laboratory of Dermatology and Immunodeficiencies, LIM-56, Department of Dermatology, Medical School, University of Sa˜o Paulo, Sa˜o Paulo, Brazil, 2 Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, Maryland, United States of America, 3 Department of Infectious Diseases and Microbiology, Center for Vaccine Research, Pittsburgh, Pennsylvania, United States of America, 4 Department of Pharmacology and Molecular Sciences, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America Infants born to HIV-infected mothers are at high risk of becoming infected during gestation or the breastfeeding period. A search is thus warranted for vaccine formulations that will prevent mother-to-child HIV transmission. The LAMP/gag DNA chimeric vaccine encodes the HIV-1 p55gag fused to the lysosome-associated membrane protein-1 (LAMP-1) and has been shown to enhance anti-Gag antibody (Ab) and cellular immune responses in adult and neonatal mice; such a vaccine represents a new concept in antigen presentation. In this study, we evaluated the effect of LAMP/gag DNA immunization on neonates either before conception or during pregnancy. LAMP/gag immunization of BALB/c mice before conception by the intradermal route led to the transfer of anti-Gag IgG1 Ab through the placenta and via breastfeeding. Furthermore, there were an increased percentage of CD4+CD25+Foxp3+T cells in the spleens of neonates. When offspring were immunized with LAMP/gag DNA, the anti-Gag Ab response and the Gag-specific IFN-c-secreting cells were decreased. Inhibition of anti- Gag Ab production and cellular responses were not observed six months after immunization, indicating that maternal immunization did not interfere with the long-lasting memory response in offspring. Injection of purified IgG in conjunction with LAMP/gag DNA immunization decreased humoral and cytotoxic T-cell responses. LAMP/gag DNA immunization by intradermal injection prior to conception promoted the transfer of Ab, leading to a diminished response to Gag without interfering with the development of anti-Gag T- and B-cell memory. Finally, we assessed responses after one intravenous injection of LAMP/gag DNA during the last five days of pregnancy. The intravenous injection led to in utero immunization. In conclusion, DNA vaccine enconding LAMP-1 with Gag and other HIV-1 antigens should be considered in the development of a protective vaccine for the maternal/fetal and newborn periods. Citation: Rigato PO, Maciel M Jr, Goldoni AL, Piubelli OG, Orii NM, et al. (2012) Maternal LAMP/p55gagHIV-1 DNA Immunization Induces In Utero Priming and a Long-Lasting Immune Response in Vaccinated Neonates. PLoS ONE 7(2): e31608. doi:10.1371/journal.pone.0031608 Editor: Paul A. Goepfert, University of Alabama, United States of America Received May 19, 2011; Accepted January 16, 2012; Published February 15, 2012 Copyright: 2012 Rigato et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by Ministe´rio da Sau´ de do Brasil – Programa Nacional de HIV/AIDS/DST (914BRA1101), Fundac¸a˜o de Amparo a` Pesquisa de Sa˜o Paulo (FAPESP nu 2004/14443-2) and Laborato´ rio de Investigac¸a˜o Me´dica, Unidade 56 do Hospital das Cl´ınicas da Faculdade de Medicina de Sa˜o Paulo. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: marisato@usp.br Introduction Despite the use of antiretroviral regimens to prevent intrapartum and breast milk HIV transmission [1], mother-to-child transmission (MTCT) of HIV-1 is still the major route of pediatric infection [2]. Effective implementation of drug regimens for long-term prophylaxis is jeopardized by several factors, such as infant toxicity and an inadequate health care infrastructure in some of the most affected countries. Vertical transmission of HIV-1 depends on the maternal HIV-1 viral load, infant exposure to infected fluids upon delivery and breastfeeding, and the duration and regimen of antiretroviral treatment [3,4]. Yet, even in the absence of treatment, 55 to 80% of infants exposed to HIV-1 remain uninfected [5]. Children who escape MTCT are again at risk of infection when they become sexually active adolescents. Vaccines that are administered to HIV-1-infected women during the neonatal period or pregnancy and that are able to induce high levels of neutralizing Ab with long-lasting effects are strong candidates for avoiding MTCT. Therefore, studying immunologic interventions, such as maternal and infant vaccine regimens, that would reduce pre- and postnatal HIV transmission remain crucial for protection against HIV infection. As the newborn immune system is not fully mature, infants are sometimes unable to mount an effective immune response against some pathogens [6,7]. Passive maternal immunization has been performed to avoid lethal viral and bacterial infections in newborns [6,8]. However, although maternal Ab represent the major form of protection against diseases in early life, their presence can also interfere with active immunizations and infant immune responses to antigens [9,6]. PLoS ONE | www.plosone.org 1 February 2012 | Volume 7 | Issue 2 | e31608