Nam Sun Cho

Prevalence of antibodies to the circumsporozite protein of Plasmodium vivax in five different regions of Korea.

Malaria has recently re‐emerged in the Republic of Korea (ROK), but only few malaria seroprevalences were reported. We obtained 1014 serum samples from inhabitants of five regions of ROK during the high transmission season between June and August in 2001. The levels of anti‐circumsporozoite protein (CSP) antibody were assessed in samples using an indirect enzyme‐linked immunosorbent assay (ELISA). The highest IgG seroreactivity against Plasmodium vivax recombinant CSP antigen was found among male residents of Cheolwon gun (13.5%), then Incheon (4.7%). The IgG seroreactivity from other regions ranged from 0.0% to 2.0%. These epidemiological data of seroprevalence in five regions of Korea showed a similar pattern to the annual incidence of malaria in these respective regions. The prevalence of antibodies increased with age, suggesting that the age and area‐related prevalence patterns reflected differences in the inoculation rates between age groups and geographic regions. Seroprevalence and annual incidence were positively correlated in some areas of Korea.

Investigation of the prevalence of human parvovirus B19 DNA in Korean plasmapheresis donors.

BACKGROUND To ensure the safety of plasma derivatives, some countries have been screening for the human parvovirus B19 (B19V) antigen or DNA in blood donors. We investigated the prevalence of B19V DNA and anti-B19V antibodies in Korean plasmapheresis donors to evaluate the necessity of B19V DNA screening test. METHODS Plasma samples were collected between March and July 2008 from 10,032 plasmapheresis donors. The B19V DNA test was performed using the LightCycler 2.0 (Roche, Germany) with quantification kits. Anti-B19V IgM and IgG were tested in 928 randomly selected samples from the 10,032 donors using recomWell Parvovirus B19 ELISA IgM, IgG assay (Mikrogen, Germany). RecomLine Parvovirus B19 LIA IgG, IgM assay (Mikrogen, Germany) was used to analyze the epitopes of antibodies in donors showing positive results for B19V DNA and anti-B19V antibodies. DNA sequencing was performed to identify the genotypes. RESULTS The prevalence of B19V DNA was 0.1% (10/10,032). Virus titers in B19V DNA positive donors were less than 10(5) IU/mL (range: 2.7 x 10(1)-3.2 x 10(4) IU/mL) except for 1 donor (1.33 x 10(8) IU/mL). All the isolated B19V DNAs from 6 donors were identified as genotype I. Nine out of 10 B19V DNA positive donors also possessed anti-B19V IgG only or IgG and IgM. The prevalence of anti-B19V IgG was 60.1% (558/928). CONCLUSIONS The prevalence of B19V DNA in Korean blood donors was not high and most donors also possessed neutralizing anti-B19V antibodies. Thus, the implementation of a B19V screening test for Korean blood donors does not appear to be imperative.

Evaluation of the Virus-elimination Efficacy of Nanofiltration (Viresolve NFP)for the Parvovirus B19 and Hepatitis A Virus

BACKGROUND The safety of plasma derivatives has been reinforced since 1980s by variable pathogen inactivation or elimination techniques. Nucleic acid amplification test (NAT) for the source plasma has also been implemented worldwide. Recently nanofiltration has been used in some country for ensuring safety of plasma derivatives to eliminate non-enveloped viruses such as parvovirus B19 (B19V) and hepatitis A virus (HAV). We evaluated the efficacy of nanofiltration for the elimination of B19V and HAV. METHODS To verify the efficacy of nanofiltration, we adopted a 20 nm Viresolve NFP (Millipore, USA) in the scaling down (1:1,370) model of the antithrombin III production. As virus stock solutions, we used B19V reactive plasma and porcine parvovirus (PPV) and HAV obtained from cell culture. And 50% tissue culture infectious dose was consumed as infectious dose. The methods used to evaluate the virus-elimination efficacy were reverse-transcriptase polymerase chain reaction for B19V and the cytopathic effect calculation after filtration for PPV and HAV. RESULTS B19V was not detected by RT-PCR in the filtered antithrombin III solutions with initial viral load of 6.42 x 10(5) IU/mL and 1.42 x 10(5) IU/mL before filtration. The virus-elimination efficacy of nanofiltration for PPV and HAV were > or = (3.32) and > or = (3.31), respectively. CONCLUSIONS Nanofiltration would be an effective method for the elimination of B19V and HAV. It may be used as a substitute for NAT screening of these viruses in source plasma to ensure safety of plasma derivatives in Korea.