ANALISIS DINAMIKA GENETIK GEN NS1 VIRUS AVIAN INFLUENZA H5N1 ISOLAT BALI

ARIEF MULYONO, Prof. drh. Widya Asmara, SU, Ph.D.

2012 | Tesis | S2 Ilmu Kedokteran Tropis

Latar Belakang. Virus AI H5N1 diperkirakan terus bermutasi yang berpotensi meningkatkan kapasitas untuk melompati barier spesies, dan dapat menular secara mudah antar manusia. Terjadinya penularan antar manusia merupakan awal dari pandemik global VAI H5N1. Gabungan semua fragmen gen (genetic makeup) VAI H5N1 tampaknya secara bersama-sama menentukan apakah suatu galur dapat menginfeksi manusia atau mamalia. Gen NS1 VAI H5N1 berperan dalam menentukan tingkat virulensi. Pulau Jawa merupakan pusat penyebaran (epicenter) virus-virus H5N1 di Indonesia. Virus-virus H5N1 ini diintroduksi dari pulau Jawa ke pulau-pulau di sekitarnya termasuk pulau Bali melalui jalur perdagangan unggas. Penelitian ini bertujuan untuk menganalisa dinamika genetik gen NS1 dan mengetahui adanya marka virulensi pada sekuen gen NS1 VAI H5N1 asal Bali. Metode. Metode yang digunakan dalam penelitian ini adalah isolasi RNA, amplifikasi gen NS1 dengan Reverse Transcriptase Polymerase Chain Reaction (RTPCR), elektroforesis dan sequencing. Data sekuen isolat virus avian influenza H5N1 asal Klungkung Bali tersebut selanjutnya dibandingkan dengan multiple aligment dengan isolat asal Indonesia lainnya dari berbagai hospes yang diakses melalui GenBank tahun 2005-2007, pembuatan pohon filogenetik, dan prediksi struktur 3 dimensi protein NS1. Hasil. Keempat isolat uji mengalami substitusi P42S dan delesi 5 asam amino pada posisi 80-84 yang mengakibatkan potensi peningkatan virulensi virus, namun tidak dijumpai adanya substitusi D92E, F103L dan M106I. Analisis filogenetik menunjukkan keempat isolat uji mempunyai kekerabatan genetik lebih dekat dengan isolat asal kucing dan manusia. Dibandingkan dengan isolat Bali tahun 2005 isolat uji mengalami peningkatan substitusi nukleotida dan asam amino. Kesimpulan. Isolat VAI H5N1 asal Bali terus mengalami dinamika genetik. Ditemukan marker virulensi pada sekuen gen NS1 isolat uji asal Bali.

Background. H5N1 virus is estimated to continue to mutate potentially increasing the capacity for passing through the barrier, and spreading out easily between human. Viral transmission between human is the beginning of a global pandemic H5N1 virus. Combination of among gene fragments (genetic makeup) H5N1 virus appears to jointly determining the virulence level. Java is epicenter H5N1 viruses in Indonesia. H5N1 viruses are being introduced from Java into surrounding islands include Bali island through the poultry trade. The aim of this study were to analyze the genetic dynamics of the NS1 gene and find out the potential virulence increase of H5N1 avian influenza origin from Klungkung Bali chicken. Methods. The method used in this study were isolation of RNA, NS1 gene amplification by Reverse Transcriptase Polymerase Chain Reaction (RT-PCR), electrophoresis and sequencing. Sequence data of avians influenza H5N1 virus isolat from Klungkung Bali was then compared with a multiple aligment with other Indonesian isolat from different hospes accessed through GenBank 2005-2007. The next step after comparing the sequence was phylogenetic analysis and prediction of three dimensional structure of the NS1 protein. Results. Four isolates underwent P42S substitution and 5 amino acid deletion at the position 80 – 84 resulting in increased virulence of the virus, but there were not found the D92E, F103L and M106I substitutions. Phylogenetics analysis revealed that four test isolates had a closer genetic relationship with the virus isolates from cat and human. The isolates test had increased of nucleotide and amino acid substitusion than isolates from Bali in 2005. Conclutions. Avian influenza virus H5N1 isolates from Bali is being dynamic genetic. Virulence marker had found on NS1 gene sequence of isolates test from Bali.

Kata Kunci : Avian Influenza, H5N1, NS1, Bali