Small Anellovirus infections in Korean children.

To the Editor: Recently, Jones et al. (1) identified circular DNA sequences, classified as Anellovirus genus, in plasma from patients with acute viral infection syndromes. These anelloviruses were then labeled as "small anellovirus (SAV)" because of their smaller genomes when compared with Torque Teno Vires (TTV) and Torque Teno Mini Virus (TTMV), which have small, circular, single-stranded DNA genomes. Although anelloviruses are not associated with any specific disease, TTV has been suggested to play a role in acute respiratory disease (ARD) and in asthma of children (2,3).

Kawasaki disease and Henoch-Schonlein purpura are important vasculitis disorders in children, possibly triggered by unknown infectious agents. Recently, Gergely et al. (4) reported that molecular mimicry involving TTV and the generation of autoantibodies may have a role in the pathogenesis of systemic lupus erythematosus. The purpose of our study was to investigate the prevalence of SAV and its association with various clinical diseases in children.

The study population comprised 81 serum samples from healthy children and 151 serum samples from children hospitalized with hepatitis (81 cases), ARD (40 cases), Kawasaki disease (12 cases), or Henoch-Schonlein purpura (18 cases) during the period January 2002-June 2006. Nasopharyngeal aspirates paired with serum samples were collected from 34 children with ARD, including upper respiratory tract infections, pneumonia, and acute bronchiolitis. Samples were collected after informed consent was obtained at admission from patients' parents.

PCRs for SAV were performed to amplify a 5' noncoding region of SAV with specific primers, as described previously (5). PCRproducts were directly sequenced, and nucleotide sequences were registered in GenBank (accession nos. DQ978791-DQ9788810). The [chi square] test with Yates correction and Mann-Whitney U-test were used for statistical comparison by using MedCalc (MedCalc Software, Mariakerke, Belgium). A p value <0.05 was defined as statistically significant.

In our study population, serum SAV DNA was detected in 28 (34.5%) of 81 children in the control group and in 66 (43.7%) of 151 children in the disease group. In the healthy control group, the SAV-positive rate was 7.4% (6/81) in children <12 months of age, 16.0% (13/81) in children 1-4 years of age, and 11.1% (9/81) in children 5-15 years of age. In the disease group, the SAV-positive rate was 35.8% (29/81) in patients with hepatitis, 67.5% (27/40) in ARD, 50% (6/12) in Kawasaki disease, and 22.2% (4/18) in Henoch-Schonlein purpura, respectively (Table). Among 34 nasopharyngeal aspirates collected from children with ARD, SAV DNA was detected in 19 (55.9%). Codetection of SAV and respiratory syncytial virus in nasopharyngeal aspirates was observed in 4 patients.

Percent similarity of nucleotide sequence of PCR products was 99% among SAV isolates. To our knowledge, this is the first report of SAV infections in children. The prevalence and role of SAV in clinical diseases have yet to be determined. Recently, Biagini et al. (5) reported that the prevalence of SAV infection was 20% (12/60) in French blood donors. In an Italian study (6), the positive rate of SAV DNA was 9.1% (5/55) in patients with hepatitis C compared with 8.6% (3/35) in healthy controls. Thus, the prevalence of SAV in Korean children is much higher than that reported in adults from other countries (5,6). Further studies are needed to confirm this finding.

In our study, the prevalence of SAV did not differ significantly between the hepatitis group and the healthy control group. Our results indicate that SAV presence does not appear to have a defining role in hepatitis, as do TTV or TTMV infection (7). In a previous study, several groups of viruses, including TTV, were ruled out as etiologic agents of Kawasaki disease (8), findings similar to those of our study. We found that the prevalence of SAV was significantly higher in patients with ARD and that SAV-positive results from serum were consistent with those of nasopharyngeal aspirates in 76% (26/34). These findings suggest that the respiratory tract may be a transmission route of SAV in children.

In conclusion, we confirmed the presence of SAV in serum samples and nasopharyngeal aspirates from Korean children. A significantly higher detection of SAV DNA was observed in children with ARD compared with healthy children or children with other clinical diseases.

References

(1.) Jones MS, Kapoor A, Lukashov VV, Simmonds P, Hecht F, Delwart E. New DNA viruses identified in patients with acute viral infection syndrome. J Virol. 2005;79:8230-6.

(2.) Maggi F, Pifferi M, Fornai C, Andreoli E, Tempestini E, Vatteroni M, et al. TT virus in the nasal secretion of children with acute respiratory disease: relation to viremia and disease severity. J Virol. 2003;77:2418-25.

(3.) Maggi F, Pifferi M, Tempestini L, Lanini L, De Marco E, Fornai C, et al. Correlation between Torque Tenovirus infection and serum levels of eosinophilic cationic protein in children hospitalized for acute respiratory disease. J Infect Dis. 2004;190:971-4.

(4.) Gergely P Jr, Pullmann R, Stancato C, Otvos L Jr, Koncz A, Blazsek A, et al. Increased prevalence of transfusion transmitted virus and cross reactivity with immunodominant epitopes of the HRES-1/ p28 endogenous retroviral autoantigen in patients with systemic lupus erythematosus. Clin Immunol. 2005; 116:124-34.

(5.) Biagini P, de Micco P, de Lamballerie X. Identification of a third member of the Anellovirus genus ("small anellovirus") in French blood donors. Arch Virol. 2006; 151:405-8.

(6.) Andreoli E, Maggi F, Pistello M, Meschi S, Vatteroni M, Nelli LC, et al. Small anellovirus in hepatitis C patients and healthy controls. Emerg Infect Dis. 2006;12: 1175-6.

(7.) Chung JY, Han TH, Hwang ES, Ko JS, Seo JK. Prevalence and genotypes of transfusion-transmitted virus in children with hepatitis [in Korean]. Korean J Pediatr Gastroenterol Nutr. 2005;8:202-12.

(8.) Chua PK, Nerurkar VR, Yu Q, Woodward CL, Melish ME, Yanagihara R. Lack of association between Kawasaki syndrome and infection with parvovirus B 19, human herpesvirus 8, TT virus, GB virus C/hepatitis G virus or Chlamydia pneumoniae. Pediatr Infect Dis J. 2000;19:477-9.

Address for correspondence: Tae Hee Han, Department of Laboratory Medicine, Sanggyepaik Hospital, Inje University College of Medicine, 761-1 Nowon-Gu, Seoul, Republic of Korea; email: [e-mail]

Ju-Young Chung, * Tae Hee Han, * Ja Wook Koo, * Sang Woo Kim, * Jeong Kee Seo, ([dagger]) and Eung Soo Hwang ([dagger])

* Inje University, Seoul, Republic of Korea; and ([dagger]) Seoul National College of Medicine, Seoul, Republic of Korea

Table. Prevalence of SAV viremia in the study population, Republic
of Korea, January 2002-June 2006 *

Group        Sex, M/F     Age range (mean age)

Control        48/33       1 mo-15 y (47 mo)
Hepatitis      44/37       1 mo-15 y (58 mo)
HBV             8/12             1-15 y
HCV             11/0             3-10 y
Others          10/9             0-13 y
Unknown        15/16            0-13 y
ARD            22/18         0-5 y (18 mo)
Vasculitis      22/8         1-10 y (46 mo)
KID              9/3              1-9 y
HSP             13/5             2-10 y
Total         136/96           1 mo-15 y

Group        No. tested    No. positive (%)          p value

Control         81             28 (34.5)
Hepatitis       81             29 (35.8)              1
HBV             20             10 (50)                0.30
HCV             11              5 (45.4)              0.71
Others          19              7 (36.8)              0.93
Unknown         31              7 (22.5)              0.3
ARD             40             27 (67.5)              0.001 ([dagger])
Vasculitis      30             10 (33.3)              0.91
KID             12              6 (50)                0.47
HSP             18              4 (22.2)              0.46
Total          232             94 (40.5)

* SAV, small anellovirus; HBV, hepatitis B virus; HCV, hepatitis C
virus; ARID, acute respiratory tract disease; KID, Kawasaki disease;
HSP, Henoch-Schonlein purpura.

([dagger]) p<0.05, statistically significant.