RESUMO
Background and Aims: African swine fever (ASF) is a highly contagious viral disease that causes major economic losses due to morbidity and fatality rates of up to 100% in wild boar and domestic pigs. The disease emerged in Africa in 1921 and then entered several European countries by 1957. In Indonesia, the first outbreak of ASF in 2019 in North Sumatra killed thousands of pigs and quickly spread to 10 out of 34 pig-producing provinces, including Bali and Eastern Nusa Tenggara. As no commercial ASF vaccine is available, the disease has become endemic and continues killing pigs. This study aimed to investigate the epidemiological and virological studies of ASF virus (ASFV) conducted in 2020 and 2021 by the Disease Investigation Center Regional VI of Denpasar Bali, which covers three provinces in Indonesia, including Bali, Western Nusa Tenggara, and Eastern Nusa Tenggara. Materials and Methods: A total of 5402 blood samples were sent to the laboratory to detect ASFV infection using quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay tests. The virological studies were performed by culturing local ASFV isolates obtained from field cases in primary macrophages and confirmation of viral growth by qPCR. Results: The qPCR results show that only 156/4528 (3.4%) of samples originating from Bali and Eastern Nusa Tenggara were ASFV-positive with cycle threshold value of 18 to 23, while the virus was not detected in Western Nusa Tenggara. Of 874 serum samples tested, 114 (13%) were antibody positive and were all collected from the two ASFV-affected provinces in 2020. A Bali ASFV isolate (BL21) was isolated and characterized molecularly. Conclusion: These findings suggest that during the time of sampling, ASFV was detected only in Bali and East Nusa Tenggara but not in Western Nusa Tenggara. These findings support the symptomology of ASFV reported in the two regions. Moreover, BL21 may be useful for developing subculture-attenuated vaccines using commercial cell lines. However, the current study has some limitations namely the investigation was not performed during the initial outbreak and no pathological examination of internal organs was conducted.
RESUMO
Background and Aim: Rabies has been endemic in Bali since 2009, and cases has recently increased. Unfortunately, there is a lack of available vaccines, which hinders the eradication program. This study aimed to investigate the epidemiological and virological aspects of rabies infection in Bali. Materials and Methods: A total of 24 brain samples were collected from rabid dogs in all districts of Bali. The samples were tested using the direct fluorescent antibody (DFA) test and polymerase chain reaction (PCR) to confirm the presence of rabies virus in the samples. Samples with the highest virus content were propagated in vivo and then inoculated into BALB/c mice. The brains of dead mice were used to prepare an inoculate cultured in murine neuroblastoma cells. Supernatant-positive viruses representing each district were then reinoculated into eight groups of five BALB/c mice. A brain sample from each dead mouse was tested using DFA and PCR and detected under a fluorescence microscope. Results: All rabies virus-positive samples collected from rabid dogs in all districts of Bali were positive. Rabies virus was detected by DFA test and PCR and was consistently confirmed in the in vivo and in vitro studies. BALB/c mice inoculated with the highest viral dilution (105 cells/mL) of culture supernatant showed typical signs of rabies, indicating that the virus could be properly investigated. Conclusion: This study demonstrated a wide epidemiological distribution of rabies in Bali. The obtained virus can be adapted for in vitro and in vivo studies and can be used to develop a homologous vaccine.
RESUMO
Conformational changes in viral membrane proteins drive membrane fusion, a critical step in virus entry and infection. Here we describe a simple and rapid virus blotting immunoassay to define conformational changes with a panel of monoclonal antibodies to distinct sites across a viral glycoprotein. This dot blot technique has been utilized to define low pH-triggered changes in the prefusion form of the herpesviral fusogen gB. At pH of <6.2 there are specific changes in herpes simplex virus 1 gB domains I and V. This corresponds broadly to host cell endosomal pH. Many of the identified changes are at least partially reversible. This method can be adapted to document changes in viral proteins that are not fusion proteins, including those induced by alternate triggers such as receptor-binding or protease cleavage.
