Genetic Variability Of Subgourp A And B Respiratory Syncytial Virus Strains Circulating In Chongqing From2009to2011

PART ONE:GENETIC VARIABILITY OF SUBGOURP A AND B RESPIRATORY SYNCYTIAL VIRUS STRAINS CIRCULATING IN CHONGQING FROM2009TO2011Objectives Human respiratory syncytial virus (RSV) is recognized as a leading pathogen responsible for severe respiratory infections in the pediatric population, particularly in infants and young children. Our previous study revealed that RSV BA strain was predominately prevalent in Southwestern China in epidemic seasons from2008to2009. This study was to further investigate the epidemiology of RSV in the following2years, the genetic variability of G gene, and the mutation at276th amino acid in the fusion (F) protein of RSV strains in the same region.Method Reverse transcription-PCR (RT-PCR) was performed to amplify a fragment of RSV G and F genes in921nasopharyngeal aspirates (NPAs) collected from inpatients with acute respiratory infections (ARIs) in Chongqing from April2009to March2011. The PCR products were sequenced and genotyped followed by phylogenetic analysis.Result Subgroup A and B RSV strains co-circulated in this area during the study period and were identified in75(35.7%) and134(63.8%) specimens of all the positive samples, respectively; both subgroup A and B viruses were identified in1(0.5%) patient. Phylogenetic analysis showed that all selected9subgroup A viruses were clustered into genotype GA2, and16subgroup B viruses into genotypes GB2and BA. The G gene of genotype BA was predicted to encode proteins with five different length.Conclution Our findings indicate that subgroup A and B RSVs alternately circulate in Southwestern China and genotype BA strains appear to be long term circulating ones. PART TWO:CIINICAL FEATURES AND MUTATION ANALYSIS OF X-LINKED AGAMMAGLOBULINEMIA IN20 CHINESE PATIENTSObjectives X-linked agammagobulinemia (XLA) is a primary immunodeficiency disorder caused by Bruton’s tyrosine kinase (BTK) gene mutation. XLA patients have an extremely small amount of peripheral B cells and profound deficiency in all immunoglobulin isotypes. We analyzed the clinical, immunologic, and molecular characteristics of children with XLA, attempting to improve the diagnosis and treatment of XLA in China.Methods Twenty children with XLA-compatible phenotype from18unrelated families were enrolled into this study. The BTK gene was amplified and sequenced, followed by mutation analysis in these children and their female relatives.Results Eighteen different mutations of BTK gene were identified in20patients. Eleven mutations had been reported previously including eight missense mutations (c.994C>T, c.1987C>A, c.1885G>T, c.502T>C, c.1085C>T, c.1816C>T, c.214C>T, c.1912G>A) and three nonsense mutations (c.1267T> A, c.1793C>G, c.1618C>T). Seven novel mutations of BTK gene were also presented and included five missense mutations (c.134T> A, c.1646T>A, c.1829C>G, c.711G>T, c.1235G>A), one splice-site mutation (c.523+1G>A) and one insertion mutation (c.1024-1025insTTGCTAAAGCAACTGCTAAAGCAAG).Eight out of eighteen mutations of BTK gene located in the TK domain, four in the PH domain, four in the SH2domain and two in the TH domain. Genetic study for carrier status was carried out in18families with definite BTK gene mutations. Nine carriers with BTK gene mutations were identified. Six families without carriers were detected and3patients were not tested in this study.Conclusions Our results further support that molecular genetic testing represents an important tool for early confirmed diagnosis of congenital agammaglobulinemia and may allow accurate carrier detection and prenatal diagnosis.