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: Bivalent vaccine for Motile Aeromonas Septicemia and Streptococcocis in Nile Tilapia (Oreochromis niloticus)
Abstrak: Etiological agents of common fish diseases are the Gram-negative Aeromonas hydrophila and the Gram-positive Streptococcus agalactiae, both are considered severe fish pathogens on account of their ability to cause damaging disease outbreaks in Nile Tilapia (Oreochromis niloticus). The occurence of co-infections between A. hydrophila and S. agalactiae at Waduk Cirata was about 20% per populations. Clinical signs appeared soon after infection, and include depression or excitability, anorexia, C-shaped body posturing, erratic swimming and whirling, and death. Aeromonas hydrophila and S. agalactiae cultures were not able to inhibit each other and showed negative results from antimicrobial activity, both are succeptible to antibitoics Tetracycline and Chloramphenicol. Nile Tilapia also were clinically examined and necropsied for histopathology, samples were taken from kidney, brain, liver, and spleen. Histopathological lesions were grouped into two characteristic patterns. The first pattern consisted focal lesion and inflammation. The second pattern consisted of multifocal lesion, necrotic, and inflammatory lesions resulting organ deformation. The mortality patterns of Nile Tilapias showed acute and chronic infections to Motile Aeromonas Septicemia, sub-acute infection to Streptococcocis. There was a homeostatic balances on hematological respons during co-infection. Aeromonas hydrophila AHL0905-2 and Streptococcus agalactiae N14G, were used as an inactivated A. hydrophila and S. agalactiae vaccine. Different vaccine preparations and formulations for vaccination of Nile Tilapia species were tried by adding neutral buffered formalin 3% to the bacterial culture (bacterin). The safety of formalin inactivated vaccine is still questionable by some aquaculture practitioners, but the sterility and safety test results of the bivalent vaccine was safe to use through intraperitoneal injection route. An antibody response was detected at the 1st week that rose significantly (p<0.05) at the 3th week post immunization in all the immunized groups. Similarly, there were significant difference (p<0.05) in the humoral immune response between groups immunized with single and mixed bacterial antigens. Upon challenge with single pathogen, a high relative percent survival was recorded in the group immunized with mixed bacterial antigens and was comparable to those fish immunized with the single bacteria. The value of relative per cent survival from bivalent vaccine mixed whole cell+ECP was 100% and 86.2% to single infections and 56.7% to co-infections, indicate that this vaccine was eficient in Nile Tilapia.
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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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