Potential transmission of human polyomaviruses through the gastrointestinal tract after exposure to virions or viral DNA

Abstract

The mechanism of human-to-human transmission of the polyomaviruses JC virus (JCV) and BK virus (BKV) has not been firmly established with regard to possible human exposure. JCV and BKV have been found in sewage samples from different geographical areas in Europe, Africa, and the United States, with average concentrations of 10(2) to 10(3) JCV particles/ml and 10(1) to 10(2) BKV particles/ml. Selected polyomavirus-positive sewage samples were further characterized. The JCV and BKV present in these samples were identified by sequencing of the intergenic region (the region found between the T antigen and VP coding regions) of JCV and the VP1 region of BKV. The regulatory region of the JCV and BKV strains found in sewage samples presented archetypal or archetype-like genetic structures, as described for urine samples. The stability (the time required for a 90% reduction in the virus concentration) of the viral particles in sewage at 20 degrees C was estimated to be 26.7 days for JCV and 53.6 days for BKV. The presence of JCV in 50% of the shellfish samples analyzed confirmed the stability of these viral particles in the environment. BKV and JCV particles were also found to be stable at pH 5; however, treatment at a pH lower than 3 resulted in the detection of free viral DNA. Since most humans are infected with JCV and BKV, these data indicate that the ingestion of contaminated water or food could represent a possible portal of entrance of these viruses or polyomavirus DNA into the human population.

FIG. 1

NJ tree constructed to represent phylogenetic relationships among 42 JCV sequences (see Table 3) for nt 2177 to 2637 of the IGR. The bootstrap confidence levels obtained for 100 replicates are shown (only significant values are indicated).

FIG. 2

Annealing of the RRs of some of the BKV-positive samples sequenced (Gardner numbering). Asterisks represent similarity between nucleotides. Bold nucleotides represent sites of diversity in the BKV genome. Archetypal (WW) and archetype-like (WW-T) sequences were also included in the annealing.

FIG. 3

Annealing of the VP1 regions of some of the BKV-positive samples sequenced. Asterisks represent similarity between nucleotides. Bold nucleotides represent sites used for BKV typing.

FIG. 4

Stability of JCV (A) and BKV (B) in sewage samples. The regression (Reg.) line, the transformed average number of genome equivalents (Gen.EQ+1) detected by nested PCR in the three samples (sewage), and the number of genome equivalents of a spiked PBS control are represented.

FIG. 5

Electrophoretic gel showing the bands obtained by analysis of a sewage sample containing JCV (A) and BKV (B) after exposure to different pHs for 30 min. The pH assayed and also the absence or presence of DNase treatment are indicated. Lanes M contained molecular size standards. C−, negative control; C+, positive control.