New prevalence estimate of TT virus (TTV) infection in low- and high-risk population from São Paulo, Brazil

The prevalence of TT virus (TTV) infection was investigated by Polymerase Chain Reaction (PCR) in low- (blood donors and healthy children/adolescents) and high-risk (hemophiliacs) groups from São Paulo, Brazil. Primers based on the untranslated region (UTR) of the viral genome proved to be much more ubiquitous, leading to much higher frequencies for both groups (>or= 81%) than the earlier N22-PCR directed to the open reading frame 1 (blood donors, 5.5%, and hemophiliacs, 42.3%). The UTR-PCR also revealed an interesting profile for healthy children/adolescents: very high prevalence at the early years and significant decrease in male teenagers. The N22-PCR, in turn, demonstrated higher frequency in hemophiliacs treated with fresh blood products (58%), than in those treated with virus-inactivated clotting factors (9.4%) and blood donors (5.5%).

Polymorphism of the TT virus and its frequency in Polish blood donors

OBJECTIVE

To determine, in Polish blood donors, the frequency of TT virus (TTV) using different primers and the sequence diversity of TTV genotypes.

MATERIALS AND METHODS

Two-hundred blood donors were studied. TTV DNA was detected by the polymerase chain reaction (PCR) using primers for the coding (ORF1) and non-coding (NC) regions. Twenty isolates were genotyped by sequencing the ORF1 fragment.

RESULTS

TTV DNA was detected in 78% of donors using NC primers and in 10% using ORF1 primers. The frequency of TTV DNA detection by NC primers was observed to increase with donor age, whereas the frequency of detection by ORF primers did not differ between various age-groups. The nucleotide sequence homology of Polish TTV isolates ranged from 59 to 99%. Three genotypes (1b, 2b and 2c) were identified.

CONCLUSIONS

The frequency of TTV detection depends on the primers used for the PCR. Using the NC primers the virus is detected in the majority of donors, whereas the ORF1 primers strongly underestimate the prevalence of TTV. The frequency of TTV DNA increases with age. Polish TTV isolates are highly polymorphic and are classified as 1b, 2b and 2c.