Human parechovirus 3 and neonatal infections

Abstract

A third serotype of human parechovirus (HPeV) has been recently isolated from stool specimens of a young Japanese child with transient paralysis. We report 3 additional cases of neonatal sepsis caused by HPeV-3 in the fall of 2001 in Canadian infants 7-27 days old. All children were hospitalized with high fever, erythematous rash, and tachypnea for a median of 5 days. The viruses isolated from nasopharyngeal aspirates grew slowly on tertiary monkey kidney cells and were successfully passaged on Vero cells. The predicted amino acid identity of the VP0-VP3-VP1 region of the three viruses was 74.6%-74.8%, 73.4%-73.6%, and 97.0%-97.1% when compared to HPeV-1, -2, and -3 prototype strains, respectively. Although different, our isolates were closely related; amino acid identity was 99.6%-100% for the last 3 proteins.

Figure 1

Comparison of the partial nucleotide sequences of human parechovirus (HPeV)-3 Canadian isolates no. 81235, 81554, and 82853 with reference sequences of HPeV-1, -2 and -3 (GenBank accession no. S45208, AF055846, and AB084913, respectively) for the 5´ untranslated region (5´ UTR; corresponding to nucleotides 595 to 699 of the HPeV-3 A308/99 strain, accession no. AB084913) (8,10). Asterisks denote identical nucleotides in all strains, whereas shaded nucleotides highlight differences between HPeV-3 isolates.

Figure 2

Phylogenetic tree showing the relationship between human parechovirus (HPeV)-3 Canadian isolates no. 81235, 81554, and 82853 and other HPeV-3 (A628-99, GenBank accession no. AB112484; A354-99, no. AB112483; A317-99, no. AB112482; A308-99, no. AB084913), HPeV-2 (Williamson, no. AJ005695; Connecticut, no. AF055846) and HPeV-1 (Harris, no. S45208; A10987-00, no. AB112487; A942-99, no. AB112486; A1086-99, no. AB112485) strains based on amino acid differences in capsid proteins (VP0-VP3-VP1 region). The tree was constructed by using the neighbor-joining method. Numbers represent the frequency of occurrence of nodes in 500 bootstrap replicas.

Figure A1

Comparison of the predicted amino acid sequences of human parechovirus (HPeV)-3 Canadian isolates no. 81235, 81554, and 82853 with reference sequences of HPeV-1, -2 and -3 (GenBank accession no. S45208, AF055846, and AB084913, respectively) for the VP0-VP3-VP1 proteins (8,10). Asterisks denote identical residues in all strains, whereas shaded amino acids highlight changes between HPeV-3 isolates. The RGD motif present only in HPeV-1 and -2 strains is underlined. The HPeV-1 immunodominant epitope described by Joki-Korpela et al. (15) is shown in bold.