Kajian Kontaminasi Virus Newcastle Disease (VND) dari Beberapa Pasar Tradisional di Wilayah Jawa Barat Dan Banten

Abstract

Newcastle disease (ND) is an important infectious disease in poultry caused by virulent Newcastle disease virus (NDV) strains of avian paramyxovirus type 1 (APMV-1). The disease is endemic in Indonesia and causes a great economic losses to the national poultry industry. The aims of this study was to examine the presence of NDV in the traditional market environment via virus isolation, identification and pathotyping using serological, molecular and biological. The study includes 30 traditional markets in West Java and Banten areas; 20 of them received intervention program to improve the hygienic practises among merchants in selling chicken meat (carcass) or live chicken. Each market sampled twice at three and six monts after the intervention program. A total of 60 pool environment samples were passaged twice in embryonated chicken eggs (ECE). The virus growth in the allantoic fluid (AF) was detected using Hemagglutination (HA). All haemagglutinating samples were further tested by molecular, serological, elution and bioassay methods. The HI test showed 13 out of 60 harvested AF have hemagglutinating activity. Further testing using real-time reverse-transcriptation polymerase chain reaction (rRT-PCR) technique targeted the matrix gene identified 12 isolatesas NDV, and 10 of them were recognized as virulent strains by rRT-PCR fusion. Antigenicexaminationof all isolates using hemaggutination inhibition (HI) test suggested antigenic variation among isolates with HI titers ranging from 3Log2 to 6Log2 and from 4,5Log2 to 6,5Log2 using lentogenic Hitchner B1 and mesogenic Komarov antisera, respectively. The 10 virulent strains identified by rRT-PCR fusion have a higher affinity to Komarov antisera. The elution test identified 1 lentogenic, 5 mesogenic and 7 velogenic strains based on their haemagglutination-elution profile, which shows a few disagreements with rRT-PCR fusion. This finding was used as the basis for selecting two isolates for bioassay using 7-day old chickens. Both fusion positive isolates, identified as lentogenic and pathogenic by elution test were deadly for the chickens, which showed clinical and pathological symptoms typical of ND. The presence of the virus was confirmed in the brain and proventriculus of all infected chickens.This shows that the elution test alone cannot be used to determine the virulence of the virus. Biosecurity intervention in the form hygienic practice improvement among sellers was expected to prevent the spread of NDV to the environment. The result revealed that following 3 months of hygienic program implementation, NDV was still detected in 7 of the 20 markets with and 4 of the 10 markets without the intervention. Significant reduction in the number of contaminated market was shown after 6 moths of intervention, in which NDV was detected only in 1 market recieving intervention. This study proves that traditional market has the potential to spread NDV to the environment, and that consistent implementation of hygienic practices can reduce NDV contamination. Other biosecurity measures need to be implemented to enable elimination of NDV from market environment.