Subtyping of Influenza A Isolates in Taiwan—2003 to 2004

Chang, Shih-Cheng; Chen, Guang-Wu; Mok, Chee-Keng; Tsao, Kuo-Chien; Huang, Chung-Guei; Huang, Ya-Ling; Shih, Shin-Ru

doi:10.1016/S0929-6646(09)60175-3

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Volume 105, Issue 11 , Pages 895-910, 2006

Subtyping of Influenza A Isolates in Taiwan—2003 to 2004

Shih-Cheng Chang
- Graduate Institute of Basic Medical Sciences, Chang Gung University, Tao-Yuan, Taiwan
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Tao-Yuan, Taiwan
Guang-Wu Chen
- Department of Computer Science and Information Engineering, Chang Gung University, Tao-Yuan, Taiwan
- Chang Gung Bioinformatics Center, Chang Gung University, Tao-Yuan, Taiwan
Chee-Keng Mok
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Tao-Yuan, Taiwan
Kuo-Chien Tsao
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Tao-Yuan, Taiwan
- Clinical Virology Laboratory, Department of Clinical Pathology, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan
Chung-Guei Huang
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Tao-Yuan, Taiwan
- Clinical Virology Laboratory, Department of Clinical Pathology, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan
Ya-Ling Huang
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Tao-Yuan, Taiwan
- Clinical Virology Laboratory, Department of Clinical Pathology, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan
Shin-Ru Shih
- Graduate Institute of Basic Medical Sciences, Chang Gung University, Tao-Yuan, Taiwan
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Tao-Yuan, Taiwan
- Clinical Virology Laboratory, Department of Clinical Pathology, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan
- Correspondence to: Dr Shin-Ru Shih, Graduate Institute of Basic Medical Sciences, Chang Gung University, 259 Wen-Hwa 1^st Road, Tao-Yuan 333, Taiwan

Received 18 October 2005; received in revised form 13 February 2006; accepted 2 May 2006.

Background/Purpose

Some isolated influenza strains are untypable. The possibility that a novel and potentially lethal strain, such as H5 virus, might be one of these untypable strains remains a major concern. This study investigated the nature of untypable influenza strains in Taiwan.

Methods

Subtyping for unsubtyped isolates was conducted by reverse transcription-polymerase chain reaction (RT-PCR) using different primer sets. Sequence determination and comparison, and characterization of viral growth rate were performed.

Results

Analysis of viral re-cultures with the different primer sets for RT-PCR revealed that all isolates were of the H3N2 subtype. All isolates resembled A/Fujian/411/02 (H3N2), and were genetically distinct from N2 of A/chicken/Taiwan/1209/03 (H5N2) on phylogenetic analysis. Real-time RT-PCR quantification of viral loads in the 16 clinical isolates revealed that negative results were partially caused by low RNA levels in the culture fluid. Comparison of replication kinetics in Madin-Darby canine kidney cells of recent influenza A H3N2 isolates showed that some Fujian-like isolates from 2003 to 2004 had significantly lower growth rate than Panama-like isolates from 2002.