1. Laboratory of Immunology, Central Laboratory of Public Health, Minister of Public Health and Social Welfare, Asunción 1429, Paraguay
2. Laboratory of Molecular Virology and Parasitology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro 21040-360, Brazil
3. Expanded Immunization Program, Minister of Public Health and Social Welfare, Asunción 1429, Paraguay
4. Molecular Applications Laboratory, Faculty of Medicine, Northeast National University, Corrientes 1240, Argentina