Judul: Polyvalent DNA Vaccine Test to Prevent Motile Aeromonad Septicemia in Tilapia (Oreochromis niloticus)
Abstrak: Kegiatan budidaya secara intensif berpeluang menimbulkan adanya infeksi penyakit oleh patogen. Bakteri yang umum menginfeksi ikan air tawar termasuk ikan nila adalah bakteri Aeromonas hydrophila dan menyebabkan penyakit motile aeromonad septicemia (MAS). Pencegahan penyakit dengan vaksinasi menjadi salah satu alternatif pengendalian MAS. Penelitian bertujuan untuk menganalisis vaksin DNA polivalen (VDP) yang diberikan secara injeksi untuk mencegah penyakit MAS pada ikan nila. Rancangan penelitian terdiri atas dua tahap, yaitu analisis pascavaksinasi dan analisis uji tantang pascavaksinasi. Vaksinasi dengan VDP mampu meningkatkan respons imunitas non-spesifik (persentase limfosit, neutrofil dan aktivitas fagositik) dan spesifik berupa peningkatan titer antibodi dari ikan nila.VDP mampu memberikan proteksi ikan nila terhadap infeksi A. hydrophila dengan tingkat perlindungan vaksin tertinggi ada pada dosis VDP 10 ng µL-1 dengan nilai RPS sebesar 70%. Hasil penelitian ini dapat digunakan sebagai acuan dalam penggunaan VDP untuk pencegahan penyakit pada ikan nila., Intensive cultivation activities have the opportunity to cause disease infection by pathogens. Bacteria that commonly infect freshwater fish, including tilapia, are Aeromonas hydrophila bacteria and cause motile aeromonad septicemia (MAS). Disease prevention by vaccination is one of the alternatives for controlling MAS. The aim of the study was to analysis the polyvalent DNA vaccine (VDP) administered by injection to prevent MAS in tilapia. The research design consisted of two stages, namely post-vaccination analysis and post-vaccination challenge test analysis. Vaccination with VDP was able to increase non-specific immune responses (percentage of lymphocytes, neutrophils and phagocytic activity) and specific in the form of increasing antibody titers from tilapia. 10 ng µL-1 with an RPS value of 70%. The results of this study can be used as a reference in the use of VDP for disease prevention in nila tilapia.
Keyword: aeromonas, antibody, tilapia, polyvalent, vaccine

Judul: Polyvalent Vaccine DNA on Tilapia (Oreochromis niloticus) to Prevent Streptococcosis
Abstrak: Pathogen that causes tilapia to develop Streptococcosis is pathogenic bacterium Streptococcus agalactiae. This study aimed to test the polyvalent DNA vaccine on tilapia (Oreochromis niloticus) infected with Streptococcosis which causes mass mortality in tilapia. The test fish in this study had a weight range of 6.73±2.25 grams with length of 7.45±2.54 cm. Streptococcus agalactiae bacterial isolates were obtained from the Aquatic Organism Health Laboratory. Tilapia was vaccinated using Streptococcus agalactiae vaccine, Aeromonas hydrophila vaccine, polyvalent vaccine dose 2.5 ng µL-1 , dose 5 ng µL-1 and dose 10 ng µL-1 and negative positive controls were only injected with PBS (Phosphate Buffered Saline) solution. Tilapia was then challenged using Streptococcus agalactiae bacteria with a density of 106 CFU mL -1 for 0.1 mL in 14 days. Parameters were performed before vaccination, after vaccination and after the trial. The test parameters observed were total erythrocytes, total leukocytes, hemoglobin levels, hematocrit levels, differential leukocytes, phagocytic activity, Relative Percent Survival (RPS), growth rate and antibody titer. Vaccination with polyvalent DNA vaccine was able to increase non-specific immune responses (total leukocytes, lymphocyte percentage, and phagocytic activity) and specific in the form of increasing antibody titers from tilapia. The survival of vaccinated tilapia was better than the control. Based on research data, the highest RPS value was found in the 10 dose polyvalent vaccine treatment. The 10 dose polyvalent vaccine RPS value was 75.56%., Patogen yang menyebabkan ikan nila terserang penyakit Streptococcosis adalah bakteri patogen Streptococcus agalactiae. Penelitian ini bertujuan menguji vaksin DNA polivalen pada ikan nila (Oreochromis niloticus) yang terinfeksi penyakit Streptococcosis penyebab kematian massal pada ikan nila. Ikan uji dalam penelitian ini memiliki kisaran bobot 6,73±2,25 g dengan panjang 7,45±2,54 cm. Isolat bakteri Streptococcus agalactiae diperoleh dari Laboratorium Kesehatan Organisme Akuatik. Ikan nila divaksin dengan menggunakan vaksin FKC, VDP dosis 2,5 ng µL-1, VDP dosis 5 ng µL-1, VDP dosis 10 ng µL-1. serta kontrol negatif dan positif hanya disuntik larutan PBS (Phosphate Buffered Saline). Ikan nila selanjutnya dilakukan uji tantang dengan menggunakan bakteri Streptococcus agalactiae dengan kepadatan 106 CFU mL-1 sebanyak 0,1 mL selama 14 hari. Pengamatan parameter dilakukan sebelum vaksinasi, setelah vaksinasi dan setelah uji tantang. Parameter uji yang diamati yaitu, total eritrosit, total leukosit, kadar hemoglobin, kadar hematokrit, diferensial leukosit, aktivitas fagositik, Relative Percent Survival (RPS), laju pertumbuhan dan titer antibodi. Vaksinasi dengan vaksin DNA polivalen mampu meningkatkan respons imunitas non spesifik (total leukosit, persentase limfosit, dan aktivitas fagositik) dan spesifik berupa peningkatan titer antibodi dari ikan nila. Kelangsungan hidup ikan nila yang divaksinasi lebih baik dibandingkan kontrol. Berdasarkan data penelitian, nilai RPS tertinggi terdapat pada perlakuan vaksin polivalen dosis 10. Nilai RPS vaksin polivalen dosis 10 yaitu 75,56%.
Keyword: DNA vaccine, fish, pathogen, polyvalent, Streptococcus agalactiae

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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