Abstract 861 Clinical Research in Developing Countries Poster Symposium, Sunday, 5/2

Recently a Japanese laboratory in pursuit of novel hepatitis viruses identified an agent provisionally designated TTV. The viral genome consists of single-stranded, linear DNA of approximately 4 kilobases and has no similarities to any known virus family. Although originally isolated from a patient with transfusion-transmitted hepatitis, nothing is known of the pathophysiology of this virus, including route of acquisition and association with disease. Viremia has been reported in 8-12% of Japanese, American, and Vietnamese blood donors and healthy adults in the UK. To establish the prevalence of TTV in children, we tested sera from two groups. The first group were medically healthy American children between the ages of 1 and 15 years. Sera were obtained by utilizing blood bank samples received for pre-operative cross matching prior to simple elective surgery or traumatic presentations. None of the children had been previously transfused as confirmed by reviewing medical records. The samples were then coded to preserve patient anonymity. The second group were children under the age of 15 years admitted to Pediatric Hospital II, Ho Chi Minh City, for evaluation and management of acute infections. All serum samples were separated and stored at -20°C prior to shipping to the United States. DNA was extracted from serum samples (200uL) using the Qiamp tissue kit (Qiagen, Inc.), according to the manufacturer's protocol with the addition of yeast tRNA to act as a carrier. Amplification was performed using semi-nested PCR with published primers NG059, NG061, NG063 and the products were analyzed by Southern hybridization using and internal 32P-end labeled oligonucleotide probe. Virus was detected in 35% (19/54) of American children and in 31% (18/59) of Vietnamese children. The prevalence of TTV varied with age: in the American group virus was found in 6/19 of the 1-5 year olds, 8/16 6-8 year olds, and 5/19 11-15 year olds; in the Vietnamese group, TTV was found in 3/19 children younger than 1 year of age, 3/12 1-5 year olds, 4/10 6-10 year olds, and 11/15 11-15 year olds children. There were no differences among the American children with respect to socioeconomic status or gender, but 58% (11/19) were African-American, 31% (6/19) were Caucasian and the remainder Hispanic or not identified. Sequencing of the 270bp product indicated marked variability between isolates (45-91%). The current gene amplification technique is not optimized to detect all TTV variants, and thus using more sensitive primers likely will reveal higher prevalence rates of this virus. Although TTV is known to be transmitted parenterally, the high prevalence rate of infection in children, as well as the high rates of viremia in tropical countries and the presence of virus in fecal samples of some patients suggests non-parenteral routes of exposure. Very little is known about TTV and more studies are required to discover the true prevalence and pathogenic nature of this novel virus.

No authors have commercial or other association that might pose a conflict of interest. The project was financed by the Division of Intramural Research, NHLBI.