ABSTRACT. This study was performed to isolate a velogenic Newcastle disease virus (NDV) strain currently found in Indonesia for establishing a domestic reference virus for future pathological and molecular epidemiological studies. A chicken suspected to have contracted Newcastle disease (ND) in a local outbreak in Bali was selected for NDV isolation. Atrophy of lymphoid tissues such as the bursa of Fabricius, thymus, and spleen; intestinal haemorrhage; and oedema of the brain were observed in the chicken. Histopathological examination revealed severe non-suppurative meningoencephalomyelitis characterised by neuronal necrosis, multifocal to diffuse gliosis, and perivascular cuffing of mononuclear cells, hemorrhagic necrosis of the trachea, intestines and bursa of Fabricius, and various degree of lymphoid depletion and necrosis of the lymphoid tissues. After ND was confirmed immunohistochemically, the NDV was propagated by inoculating tissue homogenate of the diseased chicken in embryonated eggs. Phylogenetic analysis based on the F gene nucleotide sequence revealed that this isolate belonged to genotype VII. The deduced amino acid sequence of the isolated NDV F protein at the cleavage site was 112 RRQKRF 117, which is typically found in virulent NDV isolates. Pathogenicity indexes such as the mean death time (MDT) and intracerebral pathogenicity index (ICPI) were 54 hr and 1.77, respectively. Pathological findings, phylogenetic analysis, amino acid sequence of the F protein cleavage site, and pathogenicity index test results revealed the NDV isolate, designated as NDV/ Bali-1/07, to be a novel Indonesian velogenic NDV strain belonging to group VII.KEY WORDS: Bali-1/07, LaSota, Newcastle disease virus, pathogenicity, velogenic strain.

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Background: The presence of various animals, such as: ducks, chickens and pigs in households increases the potential risks of zoonosis from animal to human. One of the diseases is Japanese encephalitis (JE). The seroepidemiological studies on the presence JE among animals especially those raised in household is very important for emerging and reemerging disease control program. Ducks, chickens and pigs have long been considered as carrier and even the amplifier hosts of Japanese encephalitis virus (JEV) replication. The presence of the animal hosts and mosquitoes as vector could result in transmission of the JEV to humans. Methods: A seroepidemiological study of the presence of Japanese encephalitis virus (JEV) was conducted by collecting sera and detecting the antibody against JEV in ducks, chickens and pigs in Bali. As pig is the amplifying animal of JEV, comparison JEV antibody between ducks reared in households with pig nearby and with no pig were also determined the presence of antibody against JEV was examined by using indirect enzyme-linked immunosorbent assay (ELISA). The serum samples with over cut off value (COV) of optical density were considered as those containing Ab against JEV.

Background and Aim: Japanese encephalitis (JE) is a zoonotic infectious inflammatory brain disease caused by the JE virus (JEV). Considerable research into the seroprevalence of JE in domestic animals has been conducted, but there have been no reports of its occurrence in wild animals, including long-tailed macaques (Macaca fascicularis). This study aimed to estimate the seroprevalence of JEV infection and its determinants in long-tailed macaques in Bali and the prevalence of mosquito vectors. Materials and Methods: Blood samples (3 mL) were collected from a population of M. fascicularis (92 heads) inhabiting a small forest with irrigated rice field nearby (wetland area) in Ubud, Gianyar, and from two populations in dryland areas with no wet rice field (Uluwatu, Badung, and Nusa Penida, Bali Province, Indonesia). The collected sera were tested for antibodies against JEV using a commercially available enzyme-linked immunosorbent assay kit (qualitative monkey JE Immunoglobulin G antibody kit). The seropositivity of the antibodies was then compared based on different variables, namely, habitat type, age, and sex. Results: The seroprevalence of the JEV antibodies in all the samples tested was found to be 41.3%. The seropositivity of the monkey serum samples collected from the wetland area was 46.4%, which was higher than the seropositivity of the sera samples collected from the dried field areas (1.25%). Monkey sera collected from the wetland areas were 6.1 times (odds ratio [OR]: 6.1; 95% confidence interval [CI]: 0.71-51.5, p>0.05) more likely to be seropositive compared to the monkey sera collected from the dried field areas. Meanwhile, female monkeys were 1.79 times (OR: 1.79; 95% CI: 0.76-4.21; p>0.05) more likely to be seropositive to JEV than males. Similarly, juvenile monkeys were 2.38 times (OR: 2.38; 95% CI: 0.98-5.79); p>0.05) more likely to be seropositive against the JEV than adult monkeys. However, none of these differences achieved statistical significance. Regarding the JEV mosquito vector collection, more Culex mosquitoes were found in the samples from the wetland areas than from the dried field areas. Conclusion: The study confirms the existence of JEV infection in long-tailed macaques in Bali. There were patterned seropositivity differences based on habitat, age, and sex of the monkeys, but these were not significant. The possibility of monkeys as a JEV reservoir and the presence of the mosquitoes as the JEV vector are suggested but require more study to confirm.

Aim: This study aimed to prepare binary ethylenimine (BEI)-inactivated virulent Newcastle disease virus (NDV) vaccine and to examine their ability to induce a protective antibody response in commercial chickens. Materials and Methods: A virulent NDV field isolate Gianyar-1/AK/2014 was propagated in chicken-embryonated eggs and was then inactivated with BEI at a concentration of 4 mM. Three groups of chickens with low-level (2 log2 hemagglutination inhibition [HI] units) maternally derived antibodies against NDV were then immunized with the BEI-inactivated vaccine. A commercial live vaccine (LaSota strain) was used as positive control, and phosphate-buffered saline (PBS) was used as negative control. A challenge experiment with a virulent NDV of Tabanan-1/ARP/2017 was performed at 3 weeks post-vaccination. Results: At 2 weeks post-immunization, the mean titers of antibodies against NDV in serum samples of chickens immunized with 0.2 mL of BEI-inactivated NDV (Group I), with live commercial NDV vaccine (Group II) and with PBS (Group III) were 3±0.94 log2 HI units, 4.9±0.99 log2 HI unit, and 0.0±0.0 HI units, respectively. At week 3 post-immunization, the mean titers of the antibodies for the three groups were 5±1.09 log2 HI units, 6.9±0.32 log2 HI units, and 0.00 HI units, respectively. The antibody titer induced by inactivated NDV Gianyar-1/AK/2014 isolates examined at 2 and 3 weeks post-vaccination was still at a significantly (p<0.01) lower level as compared to those induced by commercial life vaccine. However, the challenge test with virulent NDV of Tabanan 1/ARP/2017 isolates showed that all immunized chickens (Group I and II) survived without exhibiting any clinical sign post-challenge with the protection rates of 100%, whereas all chickens injected with PBS (Group III) died with clinical signs of ND. Conclusion: This finding shows that the BEI-inactivated vaccines prepared using virulent NDV of Gianyar-1/AK/2014 strain was able to induce protective antibody response in chickens but still at a lower level than those induce by commercial live NDV vaccine.

The increasing number of cases of acute encephalitis syndrome, a key presenting clinical sign of Japanese encephalitis infection in humans, along with increasing laboratory confirmed cases in Bali over recent years have led to the Indonesian government developing a national program of vaccination against Japanese encephalitis virus. In order to inform multidisciplinary management, a review was conducted to assess Japanese encephalitis virus-related cases in humans and animals including their determinants and detection in vectors. Along with published literature, key data from local authorized officers in Bali have been used to convey the recent situation of the disease. Related surveys detected up to 92% of the local children had antibodies against the virus with the annual incidence estimated to be 7.1 per 100,000 children. Additionally, reports on young and adult cases of infection within international travellers infected in Bali were documented with both non-fatal and fatal outcomes. Further seroprevalence surveys detected up to 90% with antibodies to the virus in animal reservoirs. The detection of the virus in certain Culex mosquito species and high levels of seropositivity may be associated with greater risk of the virus transmission to the human population. It was also highlighted that local sociocultural practices for agriculture and livestock were potentially associated with the high density of the vector and the reservoirs, which then may lead to the risk of the disease transmission in the ecology of Bali.

It was reported that 326 Japanese Encephalitis (JE) cases in Indonesia in 2016, majority cases (69.3%) occurred in Bali. It shows that Bali is a prone-area to JE incidence. Previous studies noted that JE is closely related to rural and suburban areas where rice culture and pig farming coexist. This study aims at i) determining knowledge and preventive practices of JE by farmer households; (ii) observing types of mosquitos around farmer households; and (iii) mapping the potency of JE spread using geo-spatial information. Result from this research shows that farmer households have limited knowledge and preventive actions to the incidence of Japanese encephalitis. Preventive actions carried out by respondents were not for JE incidence as such. Nonetheless, farmer’s response to source of vectors and cleanliness are good preventive actions not just to JE incidence but also for other diseases. In this research, setting up mosquito’s light traps nearby pig pens and rice fields has been successful. The result shows that Culex tritaeniorhynchus was dominant type of mosquito trapped. This is an indication that the selected areas are susceptible to the incidence of JE as the Culex sp was reported as the most competent of JE vector in Asia. Maps of the JE spread in Badung regency also coincidence with the places of Culex sp trapped and the dense of rice field. Based on the limitation of knowledge and preventive actions carried out by farmer households, it is important for the stakeholders in the regency including Regional Health Office and health care workers to socialize the occurrence of JE in the community and how to prevent against the disease.

Penyakit tetelo atau Newcastle disease (ND) adalah penyakit pada unggas yang disebabkan oleh virus dari familia Paramyxoviridae genus Avulavirus. Strain virulen menimbulkan gangguan pada sistem saraf, pencernaan dan pernafasan unggas, sementara pada embrio ayam infeksi menyebabkan gangguan pertumbuhan hingga menimbulkan kematian. Penelitian ini bertujuan untuk mengetahui efek dari virus Avian Paramyxovirus Tipe-1 (APMV-1) isolat Gianyar-1/AK/2014 terhadap perubahan histopatologi embrio ayam. Penelitian ini menggunakan tujuh butir telur ayam berembrio (TAB) berumur 11 hari yang dibagi menjadi dua kelompok perlakuan yakni kelompok kontrol sebanyak dua butir dan kelompok infektif sebanyak lima butir. Kelompok kontrol diinokulasi dengan Phosphate Buffer Saline (PBS) dan kelompok infektif diinokulasi dengan isolat APMV-1 G1/AK/2014. Dilakukan pengamatan sampai embrio mati, lalu cairan alantois dikoleksi. Cairan alantois yang diperoleh diuji dengan uji hemaglutination assay (HA) dan hemaglutination inhibition (HI). Embrio ayam dinekropsi untuk diambil organ otak, paru-paru, usus, jantung dan hati dan dimasukkan ke dalam  Neutral Buffer Formaline 10% (NBF), selanjutnya diproses lalu diwarnai dengan Hematoxilin Eosin (HE). Lesi histopatologi diamati di bawah mikroskop dan hasil pengamatan disajikan secara deskriptif. Hasil penelitian menunjukkan isolat APMV-1 G1/AK/2014 dapat mematikan embrio 48 jam pascainokulasi serta menimbulkan perubahan histopatologi dominan berupa kongesti, edema, hemoragi, degenerasi, nekrosis, peradangan pada organ otak, paru-paru, jantung, hati dan usus embrio.