Journal of Clinical Virology 57 (2013) 152–156 Contents lists available at SciVerse ScienceDirect Journal of Clinical Virology jo u r n al hom epage: www.elsevier.com/locate/jcv Rubella epidemic in Vietnam: Characteristic of rubella virus genes from pregnant women and their fetuses/newborns with congenital rubella syndrome Van Hung Pham a,b , Thong Van Nguyen c , Truc Thanh Thi Nguyen c , Linh Duy Dang b , Ngoc Hieu Hoang b , Truong Van Nguyen c , Kenji Abe a,d,∗ a Biomedical Laboratory, School of Medicine, University of Medicine and Pharmacy in Ho Chi Minh City, Ho Chi Minh City, Viet Nam b Laboratory for Molecular Diagnostics, Nam Khoa Biotek Co., Ho Chi Minh City, Viet Nam c Department of Pathology and Cytology, Hung Vuong Hospital, Ho Chi Minh City, Viet Nam d Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan a r t i c l e i n f o Article history: Received 8 November 2012 Received in revised form 31 January 2013 Accepted 10 February 2013 Keywords: Rubella Rubella virus Virus genotype Congenital rubella syndrome Vietnam Southeast Asia a b s t r a c t Background: Rubella remains poorly controlled in Southeast Asia, including Vietnam. Objectives: The aim of this study was to characterize rubella virus spread in Vietnam during 2011–2012. Study design: Amniotic fluid, throat swab and placenta samples were collected from 130 patients (110 cases from pregnant women with suspected rubella and 20 cases from fetuses/newborns). Viral RNA was obtained directly from clinical specimens, amplified by PCR, and then the E1 gene containing 739 nucleotides recommended by the WHO to identify the viral genotypes was sequenced. Results: By screening with real-time PCR, viral RNA was detectable in amniotic fluids from 103 out of 110 (93.6%) pregnant women with suspected rubella and in the throat swabs from all of 20 (100%) fetuses/newborns. In addition, viral RNA was also detected in the placenta from all cases of fetuses/newborns. All of 20 fetuses/newborns presented with congenital cataract. Twenty-four strains with the E1 gene were obtained by PCR. Using phylogenetic analysis with rubella reference sequences, all of the strains were found to be genotype 2B. Interestingly, 94% (30/32) of Vietnamese strains, includ- ing 9 strains from the database, formed an independent cluster within the genotype 2B suggesting that indigenous viruses are prevalent in this region. Conclusions: Rubella virus identified in Vietnam belonged to the genotype 2B. Importantly, the infection rate of rubella virus in fetuses/newborns was 100% and all of them had congenital cataract. Our results indicate an establishment of rubella prevention in this area is an urgent task in order to improve maternal and child health. © 2013 Elsevier B.V. All rights reserved. 1. Background Rubella is an acute infectious disease that normally has a mild clinical course. However, infections during pregnancy, especially before week 12 of gestation, can cause severe birth defects known as congenital rubella syndrome (CRS). 1 Clinical signs of CRS include cataract, glaucoma, heart disease, loss of hearing, and pigmentary retinopathy. Therefore, it is very important to control the rubella in order to improve maternal and child health worldwide. Rubella virus (RV) has no host other than humans and is thought to consist of a single serotype. However, information on ∗ Corresponding author at: Department of Pathology, National Institute of Infec- tious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo 162-8640, Japan. Tel.: +81 3 4582 2702; fax: +81 3 5285 1189. E-mail address: kenji@kih.biglobe.ne.jp (K. Abe). the epidemiologic characteristics of the virus, such as antigenic variation, virulence, and phylogenetic relationship between circu- lating strains, is in short supply. In fact, there have been only a very few epidemiologic studies conducted in Southeast Asia. 2 For the prevention of CRS, rubella-containing vaccine has been used in vaccination programs worldwide, but not in many countries in the Asian continents. The RV contains three structural polypeptides: envelope polypeptides E1 and E2 and capsid polypeptide (C). It has a single-stranded, positive-sense RNA of 9762 nucleotides as its genome. The 5 ′ -terminal two-thirds of the genome encode the nonstructural polypeptides in a single open-reading frame, and the 3 ′ -terminal one-third encodes the structural polypeptides in a single open-reading frame in the sequence of 5 ′ -C-E2-E1-3 ′ . The E1 glycoprotein is considered immunodominant in the humoral response induced against the structural proteins and contains neu- tralizing and hemagglutinating determinants. 3–7 A 739-nucletoide 1386-6532/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jcv.2013.02.008