High detection rates of TTV‐like mini virus sequences in sera from Brazilian blood donors*

TT virus (TTV) is an unenveloped virus with a single-stranded, circular DNA genome of 3,818-3,853 nucleotides (nt) that infects humans and non-human primates. Recently, the existence of a novel human virus, TTV-like mini virus (TLMV), that shows a genetic organization similar to that of TTV, but with smaller virion particle and genome, was proposed [Takahashi et al. (2000) Archives of Virology 145:979-993]. To date, no information is available with respect to the prevalence and pathogenicity of TLMV. A sensitive PCR assay was developed by using two oligonucleotide primers (LS2 and LA2) designed from the conserved non-coding region of the TLMV genome. One hundred thirty-seven sera from volunteer Brazilian blood donors were tested and 99 (72%) were TLMV DNA positive. No significant differences were observed between the groups of TLMV positive and negative subjects in relation to sex ratio, seroprevalence of TTV DNA, prevalence of anti-hepatitis A virus antibodies, area of residence, occurrence of daily contact with animals, family income, education level, and level of alanine aminotransferase. The specificity of the PCR assay was demonstrated after cloning of amplification products and determination of the nucleotide sequences (200-228 nt) of clones derived from 23 individuals. When DNAs extracted from TLMV/TTV-coinfected sera were submitted to PCR with LS2 and LA2 primers, the amplification products were derived exclusively from the TLMV genome. A markedly wide range of sequence divergence, even higher than that existent among TTV strains, was noted among TLMV isolates, with a maximum evolutionary distance of 0.80.