Whole-cell vaccine of Streptococcus agalactiae in Oreochromis sp. with immersion method
Abstract
ABSTRACT
The study was aimed to evaluate the efficacy of formalin-killed non-hemolytic Streptococcus agalactiae N14G and NK1 isolates whole-killed vaccine to prevent streptococcosis in tilapia. Ten fishes were reared in a tank 60x30x35 cm3 with an average body weight at 10.79±0.99 g. Fish was vaccinated through bath immersion at a concentration of 109 cfu/mL. Fish was subsequently challenged by intraperitonial injection of Streptococcus agalactiae 105 cfu/mL at 11 days post-vaccination. Parameters observed were survival, relative percent survival (RPS), total leukocyte, phagocytic activity, antibody titer, total erythrocyte, haemoglobin level, haematocrit level, dan water quality. Samplings were performed in day-0, 20, and 30 after vaccination. Both vaccines have shown higher survival (60%) and RPS (40%) when challenged with pathogenic Streptococcus N14G isolates than other treatments. Based on RPS percentage observed, those vaccine were still not sufficiently effective to combat S. agalactiae infection.
Keywords: tilapia, bath immersion, Streptococcus agalactiae, whole-cell vaccine
ABSTRAK
Penelitian ini bertujuan untuk mengevaluasi efikasi vaksin formalin-killed cell Streptococcus agalactiae tipe isolat nonhemolitik N14G dan NK1 se utuh yang diberikan melalui perendaman dalam mencegah penyakit streptococcosis pada ikan nila. Ikan nila yang digunakan memiliki bobot 10,79±0,99 g, dipelihara sebanyak sepuluh ekor dalam akuarium ukuran 60x30x35 cm3. Ikan divaksinasi dengan metode perendaman dengan dosis 109 cfu/mL. Uji tantang dilakukan pada hari ke-11 pascavaksinasi dengan dosis 105 cfu/mL. Parameter yang diamati meliputi sintasan (SR), sintasan relatif/relative percent survival (RPS), total leukosit, aktivitas fagositik, titer antibodi, total eritrosit, kadar hemoglobin, kadar hematokrit, dan kualitas air. Pengamatan parameter dilakukan pada hari ke-0, ke-10, ke-20, dan ke-30. Hasil penelitian menunjukkan perlakuan kedua vaksin yang diinfeksi bakteri patogen isolat N14G memberikan nilai sintasan dan nilai RPS tertinggi dibanding perlakuan lainnya. Nilai sintasan dan RPS kedua perlakuan tersebut adalah 60% dan 40%. Nilai RPS yang cukup kecil menunjukkan vaksin yang diberikan masih kurang efektif untuk mencegah infeksi bakteri S. agalactiae.
Kata kunci: ikan nila, perendaman, Streptococcus agalactiae, vaksin sel utuh
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