Distribution of TT virus genomic groups 1–5 in Brazilian blood donors, HBV carriers, and HIV‐1‐infected patients

Abstract

Human isolates of the highly prevalent TT virus (TTV) have been classified into five major genomic groups (1-5). The geographical distribution of the groups throughout the world is not well known. Five different PCR assays were developed in an attempt to amplify specifically TTV DNAs of each genomic group. Serum samples collected from 72 Brazilian adults (24 voluntary blood donors, 24 hepatitis B virus (HBV) carriers, and 24 human immunodeficiency virus type 1 (HIV-1)-infected patients) were tested. TTV DNA from at least one genomic group was detected in 11 (46%) blood donors, 13 (54%) HBV carriers, and 24 (100%) HIV-1 patients. All five genomic groups were detected in the three populations, with the exception of group 2 in blood donors. Some samples, negative with all five specific assays, were positive with the commonly used untranslated region (UTR) PCR system. On the other hand, TTV DNA was detected in some samples by using specific assays but not with the UTR PCR. Mixed infections with 2-5 TTV isolates from different groups were detected in 21% blood donors, 29% HBV carriers, and 71% HIV-1 patients. Fifteen PCR products (three obtained with each assay) were sequenced. Most sequences showed high (>86%) homology with those of TTV isolates belonging to their presumed groups. However, three sequences had low homology with all TTV sequences available from the DNA databanks. In conclusion, TTV isolates belonging to all five known genomic groups circulate in Brazil, and the results suggest the existence of new and as yet uncharacterised major genomic groups.

A multiplex PCR assay able to simultaneously detect Torque teno virus isolates from phylogenetic groups 1 to 5

“…The average number of TTV groups was higher among AIDS patients (2.54) than among health care workers (1.43). This is in accordance with previous observations based on uniplex PCR assays showing that immunosuppressed patients are more likely to be coinfected with several TTV isolates than other individuals (17,23).…”

“…These recombinant plasmids were obtained after cloning of PCR products sharing a common 20-bp segment at the 5' end (corresponding to the sense primer used for PCR). TTV sequences carried by the plasmids have been characterized in a previous study (17) and are available from GenBank under the following accession numbers: AY312145, phylogenetic group 1, 393 bp; AY312150, group 2, 678 bp; AY312152, group 3, 884 bp; AY312154, group 4, 111 bp; AY312158, group 5, 485 bp. Figure 1 shows the location of the insert DNAs in the TTV genome.…”

“…The PCR primers (T1S and T2S, sense; T1A, T2G1A, T2G2A, T2G3A, T2G4A and T2G5A, antisense) used in this study have been described previously (17).…”

“…iii) Viral DNAs extracted from serum samples were submitted to a first round of PCR using the 'universal' oligonucleotide primers T1S and T1A, that amplified a large DNA fragment covering approximately 80% of the TTV genome (17). One microliter of reaction product was used for nested multiplex PCR experiments, which were performed in the presence of six oligonucleotides in a single tube.…”

“…In a recent study, we analyzed the distribution of TTV genomic groups 1-5 among healthy individuals as well as in hepatitis B virus carriers and human immunodeficiency virus type 1-infected patients (17). This was done by using 5 different PCR assays able to specifically amplify the TTV DNAs of each phylogenetic group.…”