Role of Maternal Antibodies in Infants with Severe Diseases Related to Human Parechovirus Type 3

Abstract

Human parechovirus type 3 (HPeV3) is an emerging pathogen that causes sepsis and meningoencephalitis in young infants. To test the hypothesis that maternal antibodies can protect this population, we measured neutralizing antibody titers (NATs) to HPeV3 and other genotypes (HPeV1 and HPeV6) in 175 cord blood samples in Japan. The seropositivity rate (≥1:32) for HPeV3 was 61%, similar to that for the other genotypes, but decreased significantly as maternal age increased (p<0.001). Furthermore, during the 2014 HPeV3 epidemic, prospective measurement of NATs to HPeV3 in 45 patients with severe diseases caused by HPeV3 infection showed low NATs (≤1:16) at onset and persistently high NATs (≥1:512) until age 6 months. All intravenous immunoglobulin samples tested elicited high NATs to HPeV3. Our findings indicate that maternal antibodies to HPeV3 may help protect young infants from severe diseases related to HPeV3 and that antibody supplementation may benefit these patients.

Keywords: Human parechovirus type 3; antibody; emerging infection; infants; intravenous immunoglobulin; maternal age; meningoencephalitis; neonates; sepsis; viruses.

Figure 1

Distribution of neutralizing antibody titers to human parechovirus (HPeV) types 1, 3, and 6 in 175 cord blood samples from healthy neonates, Niigata, Japan, September 2013–January 2014. Titers are shown as reciprocal numbers. Boxes indicate first and third quartile values; bars within boxes indicate medians. Top and bottom bars indicate the 5th and 95th percentiles of data in a normal distribution. In the analysis, antibody titers <1:4 and >1:2,048 were regarded as 1 and 2,048, respectively.

Figure 2

Change in neutralizing antibody titers to human parechovirus type 3 (HPeV3) in severe diseases related to HPeV3 in neonates and infants at disease onset and at 3 and 6 months of age, Niigata, Japan.