Cobalt Chloride as a Hypoxia Mimicking Agent Induced HIF-1α and mTOR Expressions of Human Umbilical Cord Mesenchymal Stem Cells

ABSTRACT Objective: To assess the effects of cobalt chloride (CoCl2) as a hypoxia mimicking agent on human umbilical cord mesenchymal stem cells (hUCMSCs) expression of HIF-1α and mTOR for use in regenerative dentistry. Material and Methods: Human umbilical cord mesenchymal stem cells were isolated and then cultured. The characteristics of stemness were screened and confirmed by flow cytometry. The experiment was conducted on hypoxia (H) and normoxia (N) groups. Each group was divided and incubated into 24-, 48-, and 72-hours observations. Hypoxic treatment was performed using 100 µM CoCl2 on 5th passage cells in a conventional incubator (37°C; 5CO2). Then, immunofluorescence of HIF-1α and mTOR was done. Data was analyzed statistically using One-way ANOVA and Tukey's HSD. Results: Significant differences were found between normoxic and hypoxic groups on HIF-1α (p=0.015) and mTOR (p=0.000) expressions. The highest HIF-1α expression was found at 48 hours in the hypoxia group, while for mTOR at 24 hours in the hypoxia group. Conclusion: Hypoxia using cobalt chloride was able to increase human umbilical cord mesenchymal stem cells expression of HIF-1α and mTOR.

Osteoinductive and Osteogenic Capacity of Freeze-Dried Bovine Bone Compared to Deproteinized Bovine Bone Mineral Scaffold in Human Umbilical Cord Mesenchymal Stem Cell Culture: An In Vitro Study.

OBJECTIVE: Freeze-dried bovine bone scaffold (FDBB) or decellularized FDBB (dc-FDBB) was developed as an ideal scaffold with osteoinductive properties. This research aims to compare the osteoinductive properties marked by the expression of runt-related transcription factor-2 (RUNX2) and Osterix (OSX) and the osteogenic capacity of these scaffolds imbued with human umbilical cord mesenchymal stem cells (hUCMSCs). MATERIALS AND METHODS: This study was performed in five experimental groups: a negative control group (C-) of hUCMSCs with a normal growth medium, a positive control group (C + ) of hUCMSCs with an osteogenic medium, experimental group 1 (E1) with an FDBB conditioned medium (CM), and experimental group 2 (E2) with a dc-FDBB-CM, and a third experimental group (E3) consisting of a DBBM-CM. Alizarin red staining was performed to qualitatively assess osteoinductive capacity. RUNX2 and OSX expression was quantified using real-time quantification polymerase chain reaction with two replications on day six (D6) and day 12 (D12) as fold changes. RESULTS: This experiment revealed that hUCMSCs were positively expressed by CD73, CD90, and CD105 but were not expressed by CD34. Alizarin red staining showed that E1 had the most calcium deposition on D6 and D12, followed by E3 and then E2 The RUNX2 and OSX expression was higher in E1 but this difference was not significant. The OSX expression in E1,E2,E3 was lower on D12 and C+ of OSX had the highest expression. There was a significant difference of fold change measured between all groups (p < 0.05), and there was no significant difference between any of the groups treated with OSX and RUNX2 on D6 and D12. CONCLUSION: FDBB osteoinduction and osteogenic capacity were higher when compared with DBBM and dc-FDBB.

Characterization and distribution of niosomes containing ursolic acid coated with chitosan layer.

BACKGROUND AND PURPOSE: Ursolic acid (UA) exhibits anti-hepatocarcinoma and hepatoprotective activities, thus promising as an effective oral cancer therapy. However, its poor solubility and permeability lead to low oral bioavailability. In this study, we evaluated the effect of different ratios of Span® 60-cholesterol-UA and also chitosan addition on physical characteristics and stability of niosomes to improve oral biodistribution. EXPERIMENTAL APPROACH: UA niosomes (Nio-UA) were composed of Span® 60-cholesterol-UA at different molar ratios and prepared by using thin layer hydration method, and then chitosan solution was added into the Nio-UA to prepare Nio-CS-UA. FINDINGS/RESULTS: The results showed that increasing the UA amount increased the particle size of Nio-UA. However, the higher the UA amount added to niosomes, the lower the encapsulation efficiency. The highest physical stability was achieved by preparing niosomes at a molar ratio of 3:2:10 for Span® 60, cholesterol, and UA, respectively, with a zeta-potential value of -41.99 mV. The addition of chitosan increased the particle size from 255 nm to 439 nm, as well as the zeta-potential value which increased from -46 mV to -21 mV. Moreover, Nio-UA-CS had relatively higher drug release in PBS pH 6.8 and 7.4 than Nio-UA. In the in vivo study, the addition of chitosan produced higher intensities of coumarin-6-labeled Nio-UA-CS in the liver than Nio-UA. CONCLUSION AND IMPLICATIONS: It can be concluded that the ratio of Span® 60-cholesterol-UA highly affected niosomes physical properties. Moreover, the addition of chitosan improved the stability and drug release as well as oral biodistribution of Nio-UA.

The effect of chitosan addition on cellular uptake and cytotoxicity of ursolic acid niosomes.

This study evaluated the cellular uptake and cytotoxicity of low permeable Ursolic acid (UA) on cancer cells using niosomes composed of span 60 and cholesterol. The results showed that the addition of chitosan increased particle sizes and ζ-potentials. The UA niosomes with chitosan layers had higher cytotoxicity in HeLa cells than without chitosan, however, there was no improvement observed for Huh7it cells. Moreover, chitosan layers improved the cellular uptake, which clathrin-mediated endocytosis may determine the cellular transport of UA niosomes. In conclusion, the addition of chitosan improved cellular uptake and cytotoxicity of UA niosomes in the HeLa cells.

An in vitro study of dual drug combinations of anti-viral agents, antibiotics, and/or hydroxychloroquine against the SARS-CoV-2 virus isolated from hospitalized patients in Surabaya, Indonesia.

A potent therapy for the infectious coronavirus disease COVID-19 is urgently required with, at the time of writing, research in this area still ongoing. This study aims to evaluate the in vitro anti-viral activities of combinations of certain commercially available drugs that have recently formed part of COVID-19 therapy. Dual combinatory drugs, namely; Lopinavir-Ritonavir (LOPIRITO)-Clarithromycin (CLA), LOPIRITO-Azithromycin (AZI), LOPIRITO-Doxycycline (DOXY), Hydroxychloroquine (HCQ)-AZI, HCQ-DOXY, Favipiravir (FAVI)-AZI, HCQ-FAVI, and HCQ-LOPIRITO, were prepared. These drugs were mixed at specific ratios and evaluated for their safe use based on the cytotoxicity concentration (CC50) values of human umbilical cord mesenchymal stem cells. The anti-viral efficacy of these combinations in relation to Vero cells infected with SARS-CoV-2 virus isolated from a patient in Universitas Airlangga hospital, Surabaya, Indonesia and evaluated for IC50 24, 48, and 72 hours after viral inoculation was subsequently determined. Observation of the viral load in qRT-PCR was undertaken, the results of which indicated the absence of high levels of cytotoxicity in any samples and that dual combinatory drugs produced lower cytotoxicity than single drugs. In addition, these combinations demonstrated considerable effectiveness in reducing the copy number of the virus at 48 and 72 hours, while even at 24 hours, post-drug incubation resulted in low IC50 values. Most combination drugs reduced pro-inflammatory markers, i.e. IL-6 and TNF-α, while increasing the anti-inflammatory response of IL-10. According to these results, the descending order of effective dual combinatory drugs is one of LOPIRITO-AZI>LOPIRITO-DOXY>HCQ-AZI>HCQ-FAVI>LOPIRITO-CLA>HCQ-DOX. It can be suggested that dual combinatory drugs, e.g. LOPIRITO-AZI, can potentially be used in the treatment of COVID-19 infectious diseases.

A Randomized, Double-Blind, Multicenter Clinical Study Comparing the Efficacy and Safety of a Drug Combination of Lopinavir/Ritonavir-Azithromycin, Lopinavir/Ritonavir-Doxycycline, and Azithromycin-Hydroxychloroquine for Patients Diagnosed with Mild to Moderate COVID-19 Infections.

BACKGROUND: At the present time, COVID-19 vaccines are at the testing stage, and an effective treatment for COVID-19 incorporating appropriate safety measures remains the most significant obstacle to be overcome. A strategic countermeasure is, therefore, urgently required. AIM: This study aims to evaluate the efficacy and safety of a combination of lopinavir/ritonavir-azithromycin, lopinavir/ritonavir-doxycycline, and azithromycin-hydroxychloroquine used to treat patients with mild to moderate COVID-19 infections. Setting and Design. This study was conducted at four different clinical study sites in Indonesia. The subjects gave informed consent for their participation and were confirmed as being COVID-19-positive by means of an RT-PCR test. The present study constituted a randomized, double-blind, and multicenter clinical study of patients diagnosed with mild to moderate COVID-19 infection. MATERIALS AND METHODS: Six treatment groups participated in this study: a Control group administered with a 500 mg dose of azithromycin; Group A which received a 200/50 mg dose of lopinavir/ritonavir and 500 mg of azithromycin; Group B treated with a 200/50 mg dose of lopinavir/ritonavir and 200 mg of doxycycline; Group C administered with 200 mg of hydroxychloroquine and 500 mg of azithromycin; Group D which received a 400/100 mg dose of lopinavir/ritonavir and 500 mg of azithromycin; and Group E treated with a 400/100 mg dose of lopinavir/ritonavir and 200 mg of doxycycline. RESULTS: 754 subjects participated in this study: 694 patients (92.4%) who presented mild symptoms and 57 patients (7.6%) classified as suffering from a moderate case of COVID-19. On the third day after treatment, 91.7%-99.2% of the subjects in Groups A-E were confirmed negative by a PCR swab test compared to 26.9% in the Control group. Observation of all groups which experienced a significant decrease in virus load between day 1 and day 7 was undertaken. Other markers, such as CRP and IL-6, were significantly lower in all treatment groups (p < 0.05 and p < 0.0001) than in the Control group. Furthermore, IL-10 and TNF-α levels were significantly elevated in all treatment groups (p < 0.0001). The administration of azithromycin to the Control group increased CRP and IL-6 levels, while reduced IL-10 and TNF-α on day 7 (p < 0.0001) compared with day 1. Decreases in ALT and AST levels were observed in all groups (p < 0.0001). There was an increase in creatinine in the serum level of the Control, C, D, and E groups (p < 0.05), whereas the BUN level was elevated in all groups (p < 0.0001). CONCLUSIONS: The study findings suggest that the administration of lopinavir/ritonavir-doxycycline, lopinavir/ritonavir-azithromycin, and azithromycin-hydroxychloroquine as a dual drug combination produced a significantly rapid PCR conversion rate to negative in three-day treatment of mild to moderate COVID-19 cases. Further studies should involve observation of older patients with severe clinical symptoms in order to collate significant amounts of demographic data.

Cytotoxicity of Calcium Hydroxide on Human Umbilical Cord Mesenchymal Stem Cells

Abstract Objective: To examine the cytotoxicity of calcium hydroxide on human umbilical cord mesenchymal stem cells (HUCMSC) to understand the characteristics for use in regenerative dentistry procedures especially regenerative endodontics. Material and Methods: HUCMSC was isolated, cultured, and confirmed by flow cytometry. The biological characteristics, such as cell morphology, proliferation, and protein expression, were screened. To check the cytotoxicity, HUCMSC was cultured and divided into two groups, the control group (cultured in minimum essential medium (MEM) alpha) and calcium hydroxide group (cultured in MEM alpha and calcium hydroxide). Methyl-thiazole-tetrazolium (MTT) assay was done on different concentrations of calcium hydroxide (0.39 to 25 µg/mL) and the cells were observed and counted. One-way ANOVA test was used with a significance level set at 5%. Results: Flow cytometric analysis confirmed positive of CD73, CD90, CD105, negative of CD45 and CD34. A significant difference was found between the concentration of 6.25 and 3.125 µg/mL (p=0.004). There was no significant difference among 6.25, 12.5 and 25 µg/mL concentrations. There was also no significant difference among 0.39, 0.78, 1.56, and 3.125 µg/mL concentrations. Conclusion: Even though calcium hydroxide is a medicament of choice in clinical endodontics, it decreases the viability of HUCMSC. The lower the concentration of calcium hydroxide, the higher the viability of HUCMSC.

Medicinal Signaling Cells Metabolite Oral Based as a Potential Biocompatible Biomaterial Accelerating Oral Ulcer Healing (In Vitro Study).

OBJECTIVE: Medicinal signaling cells metabolite (MSCM) is often considered medical waste even though it contains abundant growth factors, and advantageous micro- and macromolecules that can accelerate healing in oral ulcer.The purpose of this experimental laboratory study was to analyze the biocompatibility and potential of MSCM, (oral based) to accelerate healing in oral ulcer (in vitro). MATERIALS AND METHODS: MSCM (oral based) was obtained by mixing 10 mL of MSCM and 2% of carboxymethyl cellulose sodium. 3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (or MTT assay) was obtained using human gingival somatic cell culture to examine cell viability treated with MSCM (oral based). Fourier transform infrared spectroscopy was performed to know the functional structure and composition of MSCM (oral based). To know the elemental composition of MSCM (oral based), energy-dispersive X-ray analysis was performed. Scratch test was performed to know the ability of MSCM (oral based) to increase human somatic cell proliferation. RESULTS: MSCM (oral based) has good cell viability. MSCM (oral based) administration accelerated the proliferation of human somatic cell culture after 12-hours in vitro. MSCM (oral based) has carboxylic acids and derivatives chemical bond. MSCM (oral based) mostly contained carbon and potassium but did not contain heavy metal substances. CONCLUSIONS: MSCM (oral based) has a biocompatible and potential ability to accelerate healing in oral ulcer in vitro. It would be useful in daily clinical practice in treating traumatic oral ulcer.

Regeneration of Salivary Gland Defects of Diabetic Wistar Rats Post Human Dental Pulp Stem Cells Intraglandular Transplantation on Acinar Cell Vacuolization and Interleukin-10 Serum Level

Abstract Objective: To investigate the regeneration of rat's salivary gland diabetic defect after intraglandular transplantation of Human Dental Pulp Stem Cells (HDPSCs) on acinar cell vacuolization and Interleukin-10 (IL-10). Material and Methods: HDPSCs isolated from the dental pulp of first premolars #34. HDPSCs from the 3rd passage was characterized by immunocytochemistry of CD73, CD90, CD105 and CD45. Twenty-four male Wistar rats, 3-month-old, 250-300 grams induced with Streptozotocin 30 mg/kg body weight to create diabetes mellitus (DM) divided into 4 groups (n=6); positive control group on Day-7; positive control group on Day-14; treatment group Day-7 (DM+5.105HDPSCs); treatment group on Day-14. On Day-7 and Day-14, rats were sacrificed. Histopathological examination performed to analyze acinar cells vacuolization while Enzyme-linked Immunoabsorbent Assay to measure IL-10 serum level. Data obtained were analyzed statistically using multiple comparisons Bonferroni test, Kruskal Wallis, Shapiro-Wilk and Levene's test result Results: The highest acinar cell vacuolization found in control group Day 14 (0.239 ± 0.132), meanwhile the lowest acinar cell vacuolization found in treatment group Day 7 (0.019 ± 0.035) with significant difference (p=0.003). The highest IL-10 serum level found in treatment group Day 14 (175.583 ± 120.075) with significant difference (p=0.001) Conclusion: Transplantation of HDPSC was able to regenerate submandibular salivary gland defects in diabetic rats by decreasing acinar cell vacuolization and slightly increase IL-10 serum level.

Osteogenic potential of gingival stromal progenitor cells cultured in platelet rich fibrin is predicted by core-binding factor subunit-α1/Sox9 expression ratio ( in vitro).

Background: Alveolar bone defect regeneration has long been problematic in the field of dentistry. Gingival stromal progenitor cells (GSPCs) offer a promising solution for alveolar bone regeneration. In order to optimally differentiate and proliferate progenitor cells, growth factors (GFs) are required. Platelet rich fibrin (PRF) has many GFs and can be easily manufactured. Core-binding factor subunit-α1 (CBF-α1) constitutes a well-known osteogenic differentiation transcription factor in SPCs. Sox9, as a chondrogenic transcription factor, interacts and inhibits CBF-α1, but its precise role in direct in vitro osteogenesis remains unknown. GSPCs cultured in vitro in PRF to optimally stimulate osteogenic differentiation has been largely overlooked. The aim of this study was to analyze GSPCs cultured in PRF osteogenic differentiation predicted by CBF-α1/Sox9. Methods: This study used a true experimental with post-test only control group design and random sampling. GPSCs isolated from the lower gingiva of four healthy, 250-gram, 1-month old, male Wistar rats ( Rattus Novergicus) were cultured for two weeks, passaged every 4-5 days. GSPCs in passage 3-5 were cultured in five M24 plates (N=108; n=6/group) for Day 7, Day 14, and Day 21 in three different mediums (control negative group: αModified Eagle Medium; control positive group: High Glucose-Dulbecco's Modified Eagle Medium (DMEM-HG) + osteogenic medium; Treatment group: DMEM-HG + osteogenic medium + PRF). CBF-α1 and Sox9 were examined with ICC monoclonal antibody. A one-way ANOVA continued with Tukey HSD test (p<0.05) based on Kolmogorov-Smirnov and Levene's tests (p>0.05) was performed. Results: The treatment group showed the highest CBF-α1/Sox9 ratio (16.00±3.000/14.33±2.517) on Day 7, while the lowest CBF-α1/Sox9 ratio (3.33±1.528/3.67±1.155) occurred in the control negative group on Day 21, with significant difference between the groups (p<0.05). Conclusion: GSPCs cultured in PRF had potential osteogenic differentiation ability predicted by the CBF-α1/sox9 ratio.

Bone alkaline phosphatase and osteocalcin expression of rat's Gingival mesenchymal stem cells cultured in platelet-rich fibrin for bone remodeling (in vitro study).

OBJECTIVE: The aim of this study was to analyze the osteogenic differentiation of rat GMSCs cultured in PRF for bone remodeling. MATERIALS AND METHODS: GMSCs were isolated from the lower gingival tissue of four healthy, 250 g, 1-month old, male rats (Rattus norvegicus) cut into small fragments, cultured for 2 weeks, and subsequently passaged every 4-5 days. GMSCs isolated in passage 3 were characterized by CD34, CD45, CD44, CD73, CD90, and CD105 using fluorescein isothiocyanate immunocytochemistry (ICC) examination. GMSCs in passage 3-5 cultured in five M24 plates (N = 108; n = 6/group) for 7, 14, and 21 days with three different mediums as follows: Control (-) group: α-Modified Eagle Medium; Control (+) group: High-dose glucose Dulbecco's Modified Eagle's Medium (DMEM-HG) + osteogenic medium; and treatment group: DMEM-HG + osteogenic medium + PRF. GMSCs were osteogenic differentiation cultured in vitro in three different mediums by bone alkaline phosphatase (BALP) and osteocalcin (OSC) marker using ICC monoclonal antibody. STATISTICAL ANALYSIS USED: The one-way analysis of variance was performed (P < 0.05) based on Shapiro-Wilk and Levene's tests (P > 0.05). RESULTS: GMSCs were shown to present + CD44, +CD73, +CD90, +CD105 and - CD34, - and CD45 expression as MSCs markers. The treatment group showed the highest BALP expression (16.00 ± 1.732) on day 7, while OSC expression (13.67 ± 2.309) on day 21 showed the statistically significant difference between groups (P < 0.05). CONCLUSION: GMSCs cultured in PRF demonstrated potential osteogenic differentiation ability capable of accelerating in vitro bone remodeling by enhancing BALP and OSC expression.

Correlation between complement component levels and disease severity in dengue patients in Indonesia.

Dengue hemorrhagic fever (DHF) is a severe form of dengue fever (DF). Recent in vitro studies indicate that complement reduces the infection-enhancing activity of dengue antibodies, suggesting its in vivo role in controlling viremia levels and disease severity. In this study, the complement hemolytic activity (CH50) and levels of complement components and related factors in dengue patients in Indonesia were assessed. Based on the number of days since fever onset, DF patients were compared with patients at the DHF pre-critical phase who showed deterioration within 2 days. The mean CH50 values and levels of C2, C4, and factors B and H in the DHF pre-critical phase group were significantly lower than those in the DF group. The mean CH50 values were significantly correlated with C4, factor B, or factor H levels, indicating their responsibility for reduced CH50 values. Furthermore, a significantly higher proportion of the DHF pre-critical phase group (78%) than the DF group (33%) was positive for the nonstructural protein 1 (NS1) antigen. These results suggested that antibody-dependent enhancement of infection occurs during a period of low complement activity, which is associated with NS1 levels during the acute phase in some patients, thereby leading to increased viremia levels and greater disease severity.

Dengue virus infection-enhancing and neutralizing antibody balance in children of the Philippines and Indonesia.

Dengue fever and dengue hemorrhagic fever are important diseases worldwide. Although antibody-dependent enhancement of infection has been proposed as a mechanism for increased disease severity, enhancing antibodies in endemic people have not been thoroughly investigated. Recently, we established a serological assay system to measure the balance of enhancing and neutralizing activities, which provides useful information for estimating in vivo antibody status. We measured the balance of these activities against four dengue virus (DENV) types in endemic populations, and analyzed the proportion of sera containing enhancing and neutralizing antibodies. Predominantly healthy Filipino children were used for analysis, although a population of Indonesian children was also investigated. In the Filipino population, the highest proportion of neutralizing activities was shown against DENV2, followed by DENV1. A greater proportion of sera exhibited enhancing rather than neutralizing antibodies against other virus types. Neutralizing activities were complement-dependent, while enhancing activities were complement-independent. The Indonesian population showed a similar dengue antibody status. Our results indicate that a relatively high proportion of endemic children possessed complement-independent enhancing antibodies against some DENV types.

Reversin increase the plasticity of bone marrow-derived mesenchymal stem cell for generation of cardiomyocyte in vitro.

AIM: to speed up transdifferentiation of bone marrow-derived stem cells into cardiomyocyte in vitro by inducing dedifferentiation of bone marrow-derived mesenchymal stem cell, before induction by 5-aza-2'-deoxycytidine into cardiomyocyte. METHODS: two-three months old 2.5 kg weight adult male New Zealanad Rabbits were anesthezied with ether, thigh bones were excised, and bone marrow cells were obtained by aspiration. RESULTS: in our experiments after 1 week of mesenchymal stem cell cultures, 20 nM reversin was given to induce dediferentiation and after 24 hours exposure with 9µM 5-aza-2-deoxycytidine, early phase of cardiomyocyte differentiation appeared as cultured cell were strongly positive for GATA-4 and weakly positive for MLC-2ά, although beating cardiomyocyte has not yet appeared at the end of experiment. These experiments also showed a marked CD34+ and c-kit+ gene expression on RT-PCR examination. CONCLUSION: reversine increase plasticity of bone marrow-derived mesenchymal stem cell to generate cardiomyocyte after 5-aza-2'-deoxycytidine induction. CD34+ and c-kit+ may be a marker for cardiomyocyte progenitor cells.

Displacement of the predominant dengue virus from type 2 to type 1 with a subsequent genotype shift from IV to I in Surabaya, Indonesia 2008-2010.

Indonesia has annually experienced approximately 100,000 reported cases of dengue fever (DF) and dengue hemorrhagic fever (DHF) in recent years. However, epidemiological surveys of dengue viruses (DENVs) have been limited in this country. In Surabaya, the second largest city, a single report indicated that dengue virus type 2 (DENV2) was the predominant circulating virus in 2003-2005. We conducted three surveys in Surabaya during: (i) April 2007, (ii) June 2008 to April 2009, and (iii) September 2009 to December 2010. A total of 231 isolates were obtained from dengue patients and examined by PCR typing. We found that the predominant DENV shifted from type 2 to type 1 between October and November 2008. Another survey using wild-caught mosquitoes in April 2009 confirmed that dengue type 1 virus (DENV1) was the predominant type in Surabaya. Phylogenetic analyses of the nucleotide sequences of the complete envelope gene of DENV1 indicated that all 22 selected isolates in the second survey belonged to genotype IV and all 17 selected isolates in the third survey belonged to genotype I, indicating a genotype shift between April and September 2009. Furthermore, in December 2010, isolates were grouped into a new clade of DENV1 genotype I, suggesting clade shift between September and December 2010. According to statistics reported by the Surabaya Health Office, the proportion of DHF cases among the total number of dengue cases increased about three times after the type shift in 2008. In addition, the subsequent genotype shift in 2009 was associated with the increased number of total dengue cases. This indicates the need for continuous surveillance of circulating viruses to predict the risk of DHF and DF.

Prevalence of antibodies to Japanese encephalitis virus among pigs in Bali and East Java, Indonesia, 2008.

Japanese encephalitis virus (JEV) is a fatal disease in Asia. Pigs are considered to be the effective amplifying host for JEV in the peridomestic environment. Bali Island and Java Island in Indonesia provide a model to assess the effect of pigs on JEV transmission, since the pig density is nearly 100-fold higher in Bali than Java, while the geographic and climatologic environments are equivalent in these areas. We surveyed antibodies to JEV among 123 pigs in Mengwi (Bali) and 96 pigs in Tulungagung (East Java) in 2008 by the hemagglutination-inhibition (HAI) test. Overall prevalences were 49% in Bali and 6% in Java, with a significant difference between them (P < 0.001). Monthly infection rates estimated from age-dependent antibody prevalences were 11% in Bali and 2% in Java. In addition, 2-mercaptoethanol-sensitive antibodies were found only from Bali samples. Further, the average HAI antibody titer obtained from positive samples was significantly higher in Bali (1:52) than Java (1:10; P < 0.001). These results indicated that JEV transmission in nature is more active in Bali than East Java.