Mosquito-specific viruses (family Flaviviridae, genus Flavivirus) Diisolasi pada Nyamuk Anopheles vagus di Bali

Mosquito-specific viruses (MSVs) adalah virus yang hanya dapat bereplikasi pada sel nyamuk. Virus ini terdiri dari berbagai genus, salah satunya yang paling banyak ditemukan adalah dari famili Flaviviridae, genus Flavivirus. Namun, data keberadaan dan karakteristik MSVs dan vektornya di Bali saat ini sangat terbatas. Oleh karena itu, pengamatan untuk memperluas penemuan keragaman vektor dan filogenetik MSVs famili Flaviviridae, genus Flavivirus di Bali dilakukan pada tahun 2016-2018. Nyamuk-nyamuk dewasa ditangkap menggunakan light trap dan dikelompokkan berdasarkan spesies. Isolasi dan propagasi virus dilakukan pada galur sel C6/36 dan baby hamster kidney-21 (BHK-21). Identifikasi virus dilakukan dengan menggunakan one step reverse-transcriptase polymerase chain reaction (RT-PCR). Terdapat dua pool yang berasal dari nyamuk Anopheles vagus menampakan cythopathic effect (CPE) hanya pada galur sel C6/36 dari total 158 pool. Virus yang diisolasi memiliki persentase identity sekuen nukleotida tertinggi 97% dan sekuen asam amino 96% dengan virus Culex theileri Flavivirus isolat JKT-8650 yang diisolasi pada tahun 1981. Selanjutnya, virus dinamakan Mosquito Flavivirus Isolate Bali (MFB) dengan accession numbers KY995166 dan KY290258. Analisis filogenetik menunjukan bahwa MFB berada satu kluster dengan Culex theileri Flavivirus (CTFV) dari Indonesia, Culex Flavivuruses-Myanmar, Culex theileri Flavivirus-Portugal, dan Mosquito Flavivirus-Turki. Terdapat delapan nukelotida dan enam asam amino yang berbeda antara MFB dan CTFV Indonesia. Pada penelitian ini dapat disimpulkan bahwa MSVs dari famili Flaviviridae, genus Flavivirus berhasil diisolasi dari nyamuk An. vagus di Bali.

Adherent and suspension baby hamster kidney cells have a different cytoskeleton and surface receptor repertoire

Animal cell culture, with single cells growing in suspension, ideally in a chemically defined environment, is a mainstay of biopharmaceutical production. The synthetic environment lacks exogenous growth factors and usually requires a time-consuming adaptation process to select cell clones that proliferate in suspension to high cell numbers. The molecular mechanisms that facilitate the adaptation and that take place inside the cell are largely unknown. Especially for cell lines that are used for virus antigen production such as baby hamster kidney (BHK) cells, the restriction of virus growth through the evolution of undesired cell characteristics is highly unwanted. The comparison between adherently growing BHK cells and suspension cells with different susceptibility to foot-and-mouth disease virus revealed differences in the expression of cellular receptors such as integrins and heparan sulfates, and in the organization of the actin cytoskeleton. Transcriptome analyses and growth kinetics demonstrated the diversity of BHK cell lines and confirmed the importance of well-characterized parental cell clones and mindful screening to make sure that essential cellular features do not get lost during adaptation.

Adherent and suspension baby hamster kidney cells have a different cytoskeleton and surface receptor repertoire

Animal cell culture, with single cells growing in suspension, ideally in a chemically defined environment, is a mainstay of biopharmaceutical production. The synthetic environment lacks exogenous growth factors and usually requires a time-consuming adaptation process to select cell clones that proliferate in suspension to high cell numbers. The molecular mechanisms that facilitate the adaptation and that take place inside the cell are largely unknown. Especially for cell lines that are used for virus antigen production such as baby hamster kidney (BHK) cells, the restriction of virus growth through the evolution of undesired cell characteristics is highly unwanted. The comparison between adherently growing BHK cells and suspension cells with different susceptibility to foot-and-mouth disease virus revealed differences in the expression of cellular receptors such as integrins and heparan sulfates, and in the organization of the actin cytoskeleton. Transcriptome analyses and growth kinetics demonstrated the diversity of BHK cell clones and confirmed the importance of well-characterized parental cell clones and mindful screening to make sure that essential cellular features do not get lost during adaptation.

Kultur Sel Baby Hamster Kidney (BHK) Menggunakan Media Dulbecco's Modified Eagle Medium (DMEM)

Kultur sel merupakan suatu proses saat sel hidup ditempatkan ke dalam suatu media yang dapat membuat sel tersebut berkembang biak atau tumbuh secara in vitro, Kultur sel dapat berupa kultur sel primer maupun cell line, Metode dalam kultur sel terdiri atas kultur monolayer dan kultur suspensi. Pembuatan media kultur untuk pertumbuhan sel diusahakan memenuhi kriteria. Konstituen dasar dari media kultur yang paling banyak digunakan adalah BSS (Balanced Sald Solution). Untuk mendapatkan pertumbuhan sel yang optimal, media kultur ditambahkan serum. Serum yang biasa digunakan dalam kultur adalah serum anak sapi (calf serum), serum fetus sapi (foetal bovine serum), serum kuda dan serum manusia. Perhitungan sel menggunakan counting chamber. Metode yang digunakan adalah revival kemudian split sel, stor sel dan menghitung sel. Hasil revival jumlah sel tertinggi didapat dari botol nomer 3 dengan jumlah sel 310 yaitu botol dengan sel BHK label tahun 2016, dan hasil split sel yang paling tinggi juga didapat dari botol kultur nomer 3 dengan jumlah sel 345 dan 311.

Single-Site Glycoprotein Mutants Inhibit a Late Event in Sindbis Virus Assembly

ABSTRACTA panel of Sindbis virus mutants that were suspected to have deficiencies in one or more aspects of their replication cycles was examined in baby hamster kidney (BHK) cells. These included an amino acid deletion (ΔH230) and substitution (H230A) in the Sindbis glycoprotein E1_H230 and similar mutants in E2_G209 (G209A, G209D, and ΔG209). Neither H230 mutation produced a measurable titer, but repeated passaging of the H230A mutant in BHK cells produced a second-site compensatory mutant (V231I) that partially rescued both H230 mutants. Electron micrograph (EM) images of these mutants showed assembled viral nucleocapsids but no completed, mature virions. EM of the compensatory mutant strains showed complete virus particles, but these now formed paracrystalline arrays. None of the E2_G209 substitution mutants had any effect on virus production; however, the deletion mutant (ΔG209) showed a very low titer when grown at 37°C and no titer when grown at 28°C. When the deletion mutant grown at 28°C was examined by EM, partially budded virions were observed at the cell surface.35S labeling of this mutant confirmed the presence of mutant virus protein in the transfected BHK cell lysate. We conclude that H230 is essential for the assembly of complete infectious Sindbis virus virions and that the presence of an amino acid at E2 position 209 is required for complete budding of Sindbis virus particles although several different amino acids can be at this location without affecting the titer.IMPORTANCEOur data show the importance of single-site mutations at E1_H230 and E2_G209 in Sindbis virus glycoproteins. These sites have been shown to affect assembly and antibody binding in previous studies. Our data indicate that mutation of one histidine residue in E1 is detrimental to the assembly of Sindbis virus particles in baby hamster kidney cells. Repeated passaging leads to a second-site substitution that partially restores the titer although EM still shows an altered phenotype. Substitutions at position G209 in E2 have no effect on titer, but deletion of this residue greatly reduces titer and again prevents assembly. When this mutant is grown at a lower temperature, virus particles bud from the host cell, but budding arrests before the progeny virus escapes. These results allow us to conclude that these sites have essential roles in assembly, and E2_G209 shows us a new viral egress phenotype.