Survey on neutralizing antibodies against Zika virus eighteen months post-outbreak in two southern Thailand communities.

BACKGROUND: In 2016 and 2017, Zika virus (ZIKV) infection outbreaks occurred in two communities in southern Thailand. This re-immerging infection can widely spread by mosquito bites and cause serious complications in a central nervous system among children born to infected mothers. Thus, they should be protected. This study aims to (1) To determine the prevalence of neutralizing ZIKV antibodies in the post-outbreak areas among the general population and pregnancy women residing at various distances from the houses of the nearest index patients; (2) To examine the cross-neutralizing capacity of antibodies against ZIKV on other flaviviruses commonly found in the study areas; (3) To identify factors associated with the presence of neutralizing ZIKV antibodies. METHODS: The two post-outbreak communities were visited at 18 months after the outbreaks. We enrolled (1) 18 confirmed ZIKV infected (index) cases, (2) sample of 554 neighbors in the outbreak areas who lived at various distances from the index patients' houses, (3) 190 residents of non-outbreak areas, and (4) all pregnant women regardless of gestational age residing in the study areas (n = 805). All serum specimens underwent the plaque reduction neutralization test (PRNT). Ten randomly selected ZIKV seropositive and ten randomly selected seronegative specimens were tested for dengue virus serotypes 1-4 (DENV1-4) and Japanese encephalitis virus (JEV) antibodies using PRNT90. Serum titer above 1:10 was considered positive. Multiple logistic regression was used to assess factors associated with seropositivity. RESULTS: Out of all 18 index cases, 9 remained seropositive. The seroprevalence (95% CI) in the two outbreak areas were 43.7% (35.9-51.6%) and 29.7% (23.3-36.0%) in general population, and 24.3% (20.1-28.8%) and 12.8% (9.7-16.5%) in pregnant women. Multivariate analysis showed that seropositivity was independent of the distance gradient from the index's houses. However, being elderly was associated with seropositivity. DENV1-4 and JEV neutralizing antibodies were present in most ZIKV-positive and negative subsamples. CONCLUSION: Protective herd immunity for ZIKV infection is inadequate, especially among pregnant women in the two post-outbreak areas in southern Thailand.

Viremic profiles in asymptomatic and symptomatic chikungunya fever: a blood transfusion threat?

BACKGROUND: The presence of a chikungunya virus (CHIKV) outbreak could have an impact on transfusion safety when there are a large number of infected persons during an epidemic. Serosurveys have found that 3% to 28% of infected persons remain asymptomatic and are potential disseminators of transfusion-associated chikungunya. However, the viremic profiles of asymptomatic chikungunya patients, the major determinant of the transfusion risk, are unknown. STUDY DESIGN AND METHODS: Data on CHIKV viremic profiles were obtained from a case-control study carried out in a chikungunya-affected area during the 2009 epidemic in Songkhla, Thailand. CHIKV-infected individuals were classified based on a combination of the patient's history and clinical and laboratory findings. RESULTS: There were 134 laboratory-proven CHIKV-infected cases, of whom 122 (91.0%) were symptomatic and 12 (9.0%) were asymptomatic. The viremic levels in the symptomatic infected individuals peaked on the first 3 days and lasted up to 8 days as defined by viral isolates. CHIKV genomic products were detected as late as Day 17 of illness. The viral loads observed in the symptomatic individuals (median, 5.6 × 10(5) plaque-forming units per milliliter [pfu/mL]; range, 1.3 × 10(1) -2.9 × 10(8) pfu/mL) were higher than but not significantly different from those observed in the viremic asymptomatic individuals (median, 3.4 × 10(3) pfu/mL; range, 8.4 × 10(1) -2.9 × 10(5) pfu/mL [p = 0.22, Wilcoxon test]). CONCLUSION: CHIKV infection is highly symptomatic and is associated with high-titred viremia. The viremic levels in asymptomatic CHIKV-infected individuals were in the range known to be capable of transmitting the disease to experimental animals. Asymptomatic CHIKV viremia individuals could be potential disseminators of transfusion-associated chikungunya.

Oral human ß-defensin 2 in HIV-infected subjects with long-term use of antiretroviral therapy.

BACKGROUND: The objectives of this study were to determine (i) oral hBD2 expression in HIV-infected subjects compared with non-HIV controls, (ii) the expression of oral hBD2 in HIV-infected subjects with antiretroviral therapy (ART) compared with those without ART, and (iii) factors associated with the expression of oral hBD2. METHODS: Oral examination and punched biopsy on buccal mucosa were performed in HIV-infected subjects with and without ART, and non-HIV individuals. The expression of hBD2 mRNA was determined by quantitative real-time PCR. Saliva samples of both un-stimulated and stimulated saliva were collected and analyzed for hBD2 levels using ELISA. Student's t-test and nonparametric multi-way ANOVA test were used for comparison of measurements between or among groups. RESULTS: One hundred and fifty-seven HIV-infected subjects were enrolled: 99 on ART (age range, 23-57 years; mean 39 years), 58 not on ART (age range, 20-59 years; mean 34 years), and 50 non-HIV controls (age range, 19-59 years; mean 36 years). The most common ART regimen was two nucleoside reverse transcriptase inhibitors + one non-nucleoside reverse transcriptase inhibitor. Salivary levels of hBD2 were significantly increased in HIV infection (P < 0.001). The levels of hBD2 in stimulated saliva were also found to be significantly different between HIV-infected subjects who were and were not on ART (P < 0.001). No significant difference was observed with the expression of hBD2 mRNA. CONCLUSION: Oral innate immunity is affected by HIV infection and use of ART. Salivary hBD2 levels may be the useful biomarkers to monitor those on long-term ART who are at risk of developing oral infections and malignant transformation.

Expression of oral secretory leukocyte protease inhibitor in HIV-infected subjects with long-term use of antiretroviral therapy.

BACKGROUND: The objectives of this study were to determine (i) the expression of oral secretory leukocyte protease inhibitor (SLPI) in HIV-infected subjects compared with non-HIV controls, (ii) the oral SLPI expression in HIV-infected subjects with antiretroviral therapy (ART) compared with those without ART, and (iii) factors associated with the expression of oral SLPI. METHODS: Oral tissues and samples of both un-stimulated and stimulated saliva were collected from HIV-infected subjects with and without ART, and non-HIV individuals. The expression of SLPI mRNA in the tissue was determined by quantitative real-time PCR. Salivary SLPI protein was detected using ELISA. Chi-square test and logistic regression analysis were performed to determine the association between HIV/ART status and the expression of oral SLPI. RESULTS: One hundred and fifty-seven HIV-infected subjects were enrolled: 99 on ART (age range, 23-57 years; mean, 39 years), 58 not on ART (age range, 20-59 years; mean, 34 years), and 50 non-HIV controls (age range, 19-59 years; mean, 36 years). The most common ART regimen was 2NRTIs + 1NNRTI. The expression of oral SLPI in stimulated saliva was significantly decreased with HIV infection (P < 0.001). The expression was also significantly different with respect to ART use (P = 0.007). Smoking, CD4(+) cell count, and HIV viral load were the factors associated with the oral SLPI expression. CONCLUSION: The expression of oral SLPI is altered by HIV infection and use of ART. Thus, oral SLPI may be the useful biomarker to identify subjects at risk of infections and malignant transformation due to HIV infection and long-term ART.

A prospective evaluation of four immunodiagnotic assays for human leptospirosis.

This was a prospective evaluation of four immunodiagnostic assays for human leptospirosis, including the indirect immunofluorescence test (IFA), the microscopic agglutination test (MAT), the LEPTO dipstick, and the latex agglutination (LA) test. Four hundred ninety-two serum samples were collected from 348 patients who presented with acute fever without localizing signs. The sensitivities of the IFA, MAT, Dipstick, and LA were 91.9, 76.6, 77.4, and 83.1%, respectively. The specificities of these assays were 100.0, 100.0, 89.3, and 83.5, respectively. Even though IFA showed the highest overall sensitivity and specificity, when acute sera were considered, the LA was the most sensitive (28.7%). All 3 genus specific antibody assays had broad reactivity against various serogroups. The MAT is best suited for the reference laboratory, where it can be maintained with the battery of live antigens; the IFA is suited for a laboratory with sophisticated equipment and technical expertise; the Dipstick and LA are suitable for peripheral laboratories which lack expensive equipment and expertise.