Characterization of a potent and highly unusual minimally enhancing antibody directed against dengue virus.

Dengue virus is a major pathogen, and severe infections can lead to life-threatening dengue hemorrhagic fever. Dengue virus exists as four serotypes, and dengue hemorrhagic fever is often associated with secondary heterologous infections. Antibody-dependent enhancement (ADE) may drive higher viral loads in these secondary infections and is purported to result from antibodies that recognize dengue virus but fail to fully neutralize it. Here we characterize two antibodies, 2C8 and 3H5, that bind to the envelope protein. Antibody 3H5 is highly unusual as it not only is potently neutralizing but also promotes little if any ADE, whereas antibody 2C8 has strong capacity to promote ADE. We show that 3H5 shows resilient binding in endosomal pH conditions and neutralizes at low occupancy. Immunocomplexes of 3H5 and dengue virus do not efficiently interact with Fcγ receptors, which we propose is due to the binding mode of 3H5 and constitutes the primary mechanism of how ADE is avoided.

Dot enzyme-linked immunosorbent assay strip as a screening tool for detection of autoantibody to interferon gamma in sera of suspected cases of adult-onset immunodeficiency.

BACKGROUND: Being able to detect the presence of autoantibodies to interferon (IFN)-γ in serum is essential for evaluating patients with suspected adult-onset immunodeficiency (AOID) with unusual intracellular infections. Most reported patients with AOID have been Asian, although the exact prevalence of this illness is unknown. To date, no standard assay exists to detect autoantibodies to IFN-γ. An easy-to-use, low-cost assay that can be performed in any laboratory would be a valuable tool for clinical management of AOID, as well as better reveal its prevalence. METHODS: Our experimental study exploited a dot enzyme-linked immunosorbent assay (Dot-ELISA) strip to detect autoantibodies to IFN-γ. Sera from 66 HIV-negative patients having autoantibodies to IFN-γ as determined by indirect ELISA were tested. RESULTS: Dot enzyme-linked immunosorbent assay was sensitive (100%) and specific (94.5%), with a positive predictive value of 97.6% and a negative predictive value of 100%. CONCLUSION: This simple method provides prompt qualitative results that can be read visually and used in facilities with limited testing capabilities.

Cell cycle arrest and apoptosis induction by methanolic leaves extracts of four Annonaceae plants.

BACKGROUND: Uvaria longipes (Craib) L.L.Zhou, Y.C.F.Su & R.M.K.Saunders, Artabotrys burmanicus A.DC, Marsypopetalum modestum (Pierre) B.Xue & R.M.K.Saunders and Dasymaschalon sp. have been used for traditional medicine to treat cancer-like symptoms in some ethnic groups of Thailand and Laos. METHODS: We evaluated the anti-cancer activity of these Annonaceae plants against several human cancer cell lines. The apoptosis induction was detected by Annexin/propidium iodide (PI) staining. Phytochemical screening was tested by standard protocols and bioactive compounds were determined by HPLC. RESULTS: The crude extracts from leaves of U. longipes, Dasymaschalon sp., A. burmanicus, and M. modestum showed particular effects that were found to vary depending on the cancer cell line, suggesting that the effect was in a cell-type specific manner. Interestingly, the induction of apoptotic cell death was prominent by the leaves-derived crude extract of M. modestum. This crude was, therefore, subjected to cell cycle analysis by PI staining. Results showed that this crude extract arrested cell cycle and increased the percentage of cells in the SubG1 phase in some cancer cell lines. The phytochemical screening tests indicated that all crude extracts contained tannins and flavonoids. HPLC of flavonoids using standards identified rutin as an active compound in U. longipes and Dasymaschalon sp., whereas quercetin was found in U. longipes and M. modestum. CONCLUSIONS: These crude extracts provide a new source for rutin and quercetin, which might be capable of inducing cancer cell apoptotic death in a cell-type specific manner. This suggests, by analyzing the major bioactive compounds, the potential use of these crudes for chemotherapy in the future.

Structural analysis of a dengue cross-reactive antibody complexed with envelope domain III reveals the molecular basis of cross-reactivity.

Dengue virus infections are still increasing at an alarming rate in tropical and subtropical countries, underlying the need for a dengue vaccine. Although it is relatively easy to generate Ab responses to dengue virus, low avidity or low concentrations of Ab may enhance infection of FcR-bearing cells with clinical impact, posing a challenge to vaccine production. In this article, we report the characterization of a mAb, 2H12, which is cross-reactive to all four serotypes in the dengue virus group. Crystal structures of 2H12-Fab in complex with domain III of the envelope protein from three dengue serotypes have been determined. 2H12 binds to the highly conserved AB loop of domain III of the envelope protein that is poorly accessible in the mature virion. 2H12 neutralization varied between dengue serotypes and strains; in particular, dengue serotype 2 was not neutralized. Because the 2H12-binding epitope was conserved, this variation in neutralization highlights differences between dengue serotypes and suggests that significant conformational changes in the virus must take place for Ab binding. Surprisingly, 2H12 facilitated little or no enhancement of infection. These data provide a structural basis for understanding Ab neutralization and enhancement of infection, which is crucial for the development of future dengue vaccines.

Safety of Oral Carica papaya L. Leaf 10% Ethanolic Extract for Acute and Chronic Toxicity Tests in Sprague Dawley Rats.

Carica papaya L. leaves, traditionally utilized in dietary supplements and pharmaceuticals, exhibit a broad spectrum of potentially therapeutic properties, including anti-inflammatory, antimalarial, and wound healing properties. This study examined the acute and chronic toxicity of 10% ethanolic-extracted C. papaya leaf in Sprague Dawley rats. The acute toxicity assessment was a single oral dose of 5000 mg/kg body weight, while the chronic toxicity assessment included daily oral doses of 100, 400, 1000, and 5000 mg/kg over 180 days. Systematic monitoring covered a range of physiological and behavioral parameters, including body and organ weights. End-point evaluations encompassed hematological and biochemical analyses, along with gross and histopathological examinations of internal organs. Findings revealed no acute toxicity in the C. papaya leaf extract group, although a significant decrease in uterine weight was observed without accompanying histopathology abnormalities. In the chronic toxicity assessment, no statistically significant differences between the control and the C. papaya leaf extract groups were detected across multiple measures, including behavioral, physiological, and hematological indices. Importantly, histopathological examination corroborated the absence of any tissue abnormalities. The study results indicate that C. papaya leaf extract exhibited no adverse effects on the rats during the 180-day oral administration period, affirming its potential safety for prolonged usage.

Impact of fine particulate matter (PM2.5) on ocular health among people living in Chiang Mai, Thailand.

Considering the limited information on the impact of PM2.5 content on ocular health, a follow-up study was conducted on 50 healthy adults. Samples were collected twice, once before the PM2.5 exposure season and again after exposure. Daily PM2.5 concentration data was gathered from Thung Satok monitoring station. All subjects completed the self-structured ocular symptom questionnaire. The concentrations of 1-OHP were determined using HPLC-FLD. Logistic regression analysis investigated the relationship between PM2.5 toxicity and ocular symptoms. The findings revealed that daily PM2.5 concentrations surpassed the WHO-recommended range by around threefold. Exposure to PM2.5 significantly raised the likelihood of ocular redness (adjusted OR: 12.39, 95% CI), watering (adjusted OR: 2.56, 95% CI), and dryness (adjusted OR: 5.06, 95% CI). Additionally, these symptoms had an exposure-response relationship with increasing 1-OHP levels. Ocular symptoms worsened in frequency and severity during the high PM2.5 season, showing a strong link to elevated PM2.5 levels. Lymphocyte counts were also positively correlated with redness, watering, and dryness during high PM2.5 exposure. In conclusion, our study shows that subjects exposed to higher PM2.5 levels presented more significant ocular surface alterations.

Safety and immunogenicity of CoronaVac and ChAdOx1 heterologous prime-boost vaccines in an overweight population in Chiang Mai, Thailand.

Background: In early 2021, the Ministry of Public Health of Thailand announced heterologous regimens for COVID-19 vaccines using CoronaVac as the first dose followed by ChAdOx1 nCoV-19 at 3 weeks apart. Priority was given to individuals above 60 years old and those who had seven underlying conditions, including obesity. The vaccine regimen was evaluated for safety and immunogenicity in overweight populations in Chiang Mai, Thailand. Methods: Participants who had a COVID-19 vaccination appointment for the heterologous prime-boost regimen were enrolled. Before each immunization and on day 28 following the second dosage, blood samples were taken, and were examined for anti-spike and neutralizing antibodies by using an indirect ELISA and virus neutralization assays. Safety profile of the vaccine regimen was assessed via a self-recorded diary of adverse events after each vaccination. Results: No serious adverse events related to vaccination were reported during study period and the majority of adverse reactions were fatigue and pain at the injection site. The levels of anti-spike IgG were 26.3, 56.4 and 1752.1 BAU/mL at baseline, 21 days after first dose and 28 days after second dose, respectively. At 4 weeks after complete vaccination, the median inhibition rates of neutralizing antibody determined by surrogate neutralization assay against wild type, Delta and Omicron variants were 95.2, 85.0 and 3.8, respectively. Moreover, the NT50 level against wild type and Delta variants determined by pseudotyped virus neutralization assay were 133.3 and 41.7, respectively. The neutralizing activity against Omicron variant was almost lower than cutoff level for detection. Conclusions: The heterologous CoronaVac-ChAdOx1vaccination was safe, well-tolerated and able to induce humoral immunity against wild-type and Delta variants but not against the Omicron variant in overweight population.

Effects of quercetin and extracts from Phyllanthus emblica, Morus alba, and Ginkgo biloba on platelet recovery in a rat model of chemotherapy-induced thrombocytopenia.

Background: Chemotherapy-induced thrombocytopenia (CIT) is a major reason for chemotherapy delays, dose reduction, or even treatment discontinuation, which may impact oncologic outcomes. We investigated the effects of quercetin and extracts of Phyllanthus emblica fruit (PEE), Morus alba leaf (MAE), and Ginkgo biloba leaf (GBE) on platelet recovery in a rat model of chemotherapy-induced thrombocytopenia. Methods: The total phenolic content (TPC), total flavonoid content (TFC), quercetin content, and antioxidant activities of all the extracts were determined. Sixty male Sprague Dawley rats were categorized into healthy controls and CIT groups. The CIT groups was administered a cyclophosphamide solution, while the control group received a saline solution. Each group was then subdivided into five subgroups of six animals which were administered with PEE, MAE, GBE, quercetin, or a vehicle for 15 days. Results: The highest quercetin content was found in PEE, followed by MAE and GBE, which correlated with their antioxidant properties. Administration of these extracts and quercetin did not significantly change the platelet counts in healthy rats. Thrombocytopenic rats treated with PEE, MAE, and GBE also were not associated with significant changes in platelet counts. However, more rapid platelet count recovery was observed in all groups receiving extracts. On day 11, platelet counts in the PEE, MAE, and GBE groups returned to near baseline levels with a mean of 4.29 %, -40.77 %, and -14.24 %, respectively, compared to -71 % in the CIT group. In thrombocytopenic rats treated with quercetin, there was a significant increase in platelet counts on days 9 and 11, with a mean decrease of 5.41 % from baseline on day 11. Conclusion: Quercetin improved platelet recovery in the animal model of CIT. This finding merits for further investigation to better elucidate the health benefits of quercetin and quercetin-rich plants and potential pharmacokinetics underpinning their activity in thrombocytopenia.

Short-lived IFN-γ effector responses, but long-lived IL-10 memory responses, to malaria in an area of low malaria endemicity.

Immunity to malaria is widely believed to wane in the absence of reinfection, but direct evidence for the presence or absence of durable immunological memory to malaria is limited. Here, we analysed malaria-specific CD4+ T cell responses of individuals living in an area of low malaria transmission in northern Thailand, who had had a documented clinical attack of P. falciparum and/or P. vivax in the past 6 years. CD4+ T cell effector memory (CD45RO+) IFN-γ (24 hours ex vivo restimulation) and cultured IL-10 (6 day secretion into culture supernatant) responses to malaria schizont antigens were detected only in malaria-exposed subjects and were more prominent in subjects with long-lived antibodies or memory B cells specific to malaria antigens. The number of IFN-γ-producing effector memory T cells declined significantly over the 12 months of the study, and with time since last documented malaria infection, with an estimated half life of the response of 3.3 (95% CI 1.9-10.3) years. In sharp contrast, IL-10 responses were sustained for many years after last known malaria infection with no significant decline over at least 6 years. The observations have clear implications for understanding the immunoepidemiology of naturally acquired malaria infections and for malaria vaccine development.

Placental Transfer Immunity to the Newborns in a Twin Pregnant Women Vaccinated with Heterologous CoronaVac-ChAdOx1.

Pregnant women who receive the COVID-19 vaccine develop anti-SARS-CoV-2 antibodies, which can be transferred to the fetus. However, the effectiveness of placental transfer has not been evaluated in twin pregnancy, especially in cases vaccinated with heterologous CoronaVac (Sinovac)-ChAdOx1 (Oxford-AstraZeneca) regimen, which was commonly used in many countries. Case: A 34-year-old Thai woman with a twin pregnancy attended our antenatal care clinic at 21 + 2 weeks of gestation and requested COVID-19 vaccination. Her medical history and physical examination were unremarkable. She had not received COVID-19 vaccination before. Ultrasound screening for fetal anomaly revealed a dichorion diamnion twin pregnancy. Both twins showed no structural anomaly. She received the CoronaVac vaccine at 21 + 2 weeks of gestation without serious side effects and the ChAdOx1 vaccine at 24 + 2 weeks of gestation. Cesarean delivery was performed at 36 + 5 weeks of gestation, giving birth to the two healthy babies. The levels of anti-spike protein IgG levels (BAU/mL) in maternal blood just before delivery and umbilical cord blood of the two newborns were 313.349, 678.219, and 874.853, respectively. The levels of % inhibition (wild-type and delta) in the two newborns were also higher than those in the mother. In conclusion, heterologous CoronaVac-ChAdOx1-S vaccination in a twin pregnancy could effectively provide protective immunity to both twin newborns. The antibody levels in both were approximately two times higher than those in the mothers. This case report may serve as a reference in counseling couples with a twin pregnancy, while the studies on placental transfer of vaccine-derived antibodies in twin pregnancy are currently not available, especially in countries experiencing a vaccine shortage or unavailability of mRNA vaccines.

A preliminary study on the effectiveness of maternal to neonatal transfer of antibodies against SARS-CoV-2 in the women vaccinated with heterologous CoronaVac-ChAdOx1.

The objective is to evaluate the effectiveness of placental transfer of maternally derived SARS-CoV-2 IgG antibodies after the vaccination of pregnant women with heterologous CoronaVac-ChAdOx1. Thirty pregnant women were vaccinated with CoronaVac as the first dose, followed by ChAdOx1 3 weeks later. The antibody levels in the maternal blood and in the umbilical cord blood at the time of delivery were determined. The results showed that the vaccination effectively increased antibody levels in both mothers and newborns. The antibody levels in the mothers were strongly correlated with those in the newborns (P < .001). The high levels of passive immunity in the newborns were achieved when the first and second doses of vaccination were given more than 40 and 20 d before delivery, respectively. After 1 month of the second dose, the immune levels seemed to decline in the mothers but increase in the newborns. The antibody levels in the newborns appear to be higher than those in the mothers in cases of delivery after 20 d of the second dose (1419 ± 699 vs 1222 ± 593 BAU/L; p < .05). In conclusion, heterologous CoronaVac-ChAdOx1-S schedule can increase antibody levels in a short time during pregnancy. Also, the regimen effectively increases immunity in the newborns. The antibody levels in the newborns appear to be higher than that in the mothers in most cases, if receiving the second dose more than 3 weeks before delivery. Therefore, the regimen should be considered as an effective regimen for pregnant women, especially in settings where mRNA vaccine is not available.

In-vitro antimalarial activity of methanolic leaf- and stem-derived extracts from four Annonaceae plants.

OBJECTIVE: Plants in the Annonaceae family are known for having abundant biologically active secondary metabolites. They have been used in alternative drugs for various diseases in several countries, for instance, the bark of Cananga odorata (Lam.) Hook and Thomson is used for Ophthalmic inflammation and wound healing in Malaysia. Extracts from the leaves and stems of four Annonaceae plants, namely Uvaria longipes (Craib) L.L.Zhou, Y.C.F.Su & R.M.K.Saunders, Dasymaschalon sp., Artabotrys burmanicus A.DC, and Marsypopetalum modestum (Pierre) B.Xue & R.M.K.Saunders were investigated for growth inhibitory activity against blood-stage Plasmodium falciparum growth in vitro and for non-specific cytotoxicity against normal peripheral blood mononuclear cells (PBMCs). Antimalarial activity was assessed by invasion inhibition assay and the percentage of infected red blood cells on blood smears were determined. Cytotoxicity was tested by culturing PBMCs with the extracts, and viabilities were determined by Annexin V/propidium iodide staining. RESULTS: A. burmanicus stem extract and M. modestum leaf extract were capable of inhibiting growth of P. falciparum when used at 200 µg/mL compared to chloroquine. The extracts at effective concentrations, did not affect the viability of PBMCs. These results support further need for characterization of active compounds from specific Annonaceae plants in order to exploit their components for potential malaria treatment.

Diagnostic performance between in-house and commercial SARS-CoV-2 serological immunoassays including binding-specific antibody and surrogate virus neutralization test (sVNT).

This study aimed to evaluate the correlation between in-house and commercial binding-specific IgG antibodies and between in-house and commercial SARS-CoV-2 surrogate virus neutralization tests (sVNT). Samples from healthcare workers who received vaccines against SARS-CoV-2 were tested for RBD-specific antibody, S-specific antibody, and in-house ELISA, commercial sVNT, and in-house sVNT, against wild-type SARS-CoV-2. Three hundred and five samples were included in the analysis. The correlation between S-specific binding antibodies and in-house ELISA was 0.96 (95% CI 0.96-0.97) and between RBD-specific antibodies and in-house ELISA was 0.96 (95% CI 0.95-0.97). The Cohen's kappa between in-house sVNT and the commercial test was 0.90 (95% CI 0.80, 1.00). If using 90% inhibition of sVNT as the reference standard, the optimal cut-off value of RBD-specific antibodies was 442.7 BAU/mL, the kappa, sensitivity, and specificity being 0.99, 99%, and 100%, respectively. The optimal cut-off value of S-specific antibodies was 1155.9 BAU/mL, the kappa, sensitivity, and specificity being 0.99, 100%, and 99%, respectively. This study demonstrated a very strong correlation between in-house ELISA and 2 commercial assays. There was also a very strong correlation between in-house and commercial SARS-CoV-2 sVNT, a finding of particular interest which will inform future research.

Comparison of antibody responses following natural infection with Severe Acute Respiratory Syndrome Coronavirus 2 or receipt of CoronaVac or ChAdOx1 (AZD1222) vaccination in Chiang Mai, Thailand.

Background: In Thailand, early vaccination initiatives for SARS-CoV-2 relied on CoronaVac (Sinovac Life Sciences) and ChAdOx1 (Oxford-AstraZeneca) vaccines. However, the data of immunogenicity of these two vaccines in Thai populations is limited. This real time, head-to-head comparative study was conducted to investigate antibody (Ab) responses to SARS-CoV-2 following infection or receipt of either CoronaVac or ChAdOx1 vaccination in Chiang Mai, Thailand. Methods: Sera was collected within two months from participants having a history of documented SARS-CoV-2 infection or at one month after the second dose of CoronaVac vaccine. Sera from participants with a history of receiving one dose of ChAdOx1 vaccination was collected twice, at one month following each vaccine dose. Neutralizing antibodies (NAbs) were assessed using the surrogate neutralization test and anti-spike protein antibodies were assessed using an in-house enzyme-linked immunosorbent assay. Results: The prevalence of NAbs against SARS-CoV-2 was 92.1 %, 95.7 %, 64.1 % and 100 % in the infection group, CoronaVac group, ChAdOx1 group after 1st dose, and ChAdOx1 group after 2nd dose, respectively. The inhibition rate in individuals receiving two doses of ChAdOx1 vaccine (90.8%) was significantly higher than individuals who had recovered from natural infection (71.7%) or individuals who had received two doses of CoronaVac vaccine (66.7%). The prevalence of anti-spike Abs was 97.4 %, 97.8 %, 97.4 % and 100 % in the infection group, CoronaVac group, ChAdOx1 group after 1st dose, and ChAdOx1 group after 2nd dose, respectively. Significantly higher levels of anti-spike Abs were observed in the ChAdOx1 group after two doses of vaccination (1975 AU/mL) compared to those who had recovered from natural infection (468.5 AU/mL) and individuals who had received CoronaVac (554.4 AU/mL). Neutralizing activity had a statistically significant positive correlation with levels of anti-spike Abs. Conclusions: ChAdOx1 vaccine may provide superior immunogenicity than CoronaVac and natural infection.

Comparison of Immunogenicity and Reactogenicity of Five Primary Series of COVID-19 Vaccine Regimens against Circulating SARS-CoV-2 Variants of Concern among Healthy Thai Populations.

To compare immunogenicity and reactogenicity of five COVID-19 vaccine regimens against wild-type SARS-CoV-2 and variants of concern (VoCs) among Thai populations, a prospective cohort study was conducted among healthy participants aged ≥18 years who had never been infected with COVID-19 and were scheduled to get one of the five primary series of COVID-19 vaccine regimens, including CoronaVac/CoronaVac, AZD1222/AZD1222, CoronaVac/AZD1222, AZD1222/BNT162b2, and BNT162b2/BNT162b2. Anti-receptor binding domain (anti-RBD-WT) IgG and neutralizing antibody (NAb-WT) against wild-type SARS-CoV-2 were measured at pre-prime, post-prime, and post-boost visits. NAb against VoCs (NAb-Alpha, NAb-Beta, NAb-Delta, and NAb-Omicron) were assessed at the post-boost visit. Adverse events (AEs) following vaccination were recorded. A total of 901 participants (CoronaVac/CoronaVac: 332, AZD1222/AZD1222: 221, CoronaVac/AZD1222: 110, AZD1222/BNT162b2: 128, and BNT162b2/BNT162b2: 110) were enrolled. Anti-RBD-WT IgG and NAb-WT levels increased substantially after each vaccine dose. At the post-boost visit, BNT162b2/BNT162b2 induced the highest GMC of anti-RBD-WT IgG level (1698 BAU/mL), whereas AZD1222/BNT162b2 induced the highest median NAb-WT level (99% inhibition). NAb levels against VoCs, particularly the Omicron strain, were markedly attenuated for all vaccine regimens (p < 0.001). Overall, no serious AEs following vaccination were observed. All five primary series of COVID-19 vaccine regimens were well-tolerated and elicited robust antibody responses against wild-type SARS-CoV-2 but had attenuated responses against VoCs, particularly the Omicron strain, among healthy Thai populations.

Safety and immunogenicity of the third and fourth doses of vaccine against SARS-CoV-2 following a 2-dose regimen of inactivated whole-virion SARS-CoV-2 vaccine.

This study followed healthcare personnel (HCP) who had completed a primary series of CoronaVac and then received the third and fourth doses of COVID-19 vaccine. The primary objective was to determine the seroconversion rate of neutralizing antibodies against wild-type SARS-CoV-2 and VOCs at day 28 after the third dose of vaccine and day 28 after the fourth dose of vaccine. This prospective cohort study was conducted at Maharaj Nakorn Chiang Mai Hospital, a tertiary care hospital affiliated to Chiang Mai University from July 2021 to February 2022. Two hundred and eighty-three participants were assessed for eligibility; 142 had received AZD1222 and 141 BNT162b2 as the third dose. Seroconversion rates using a 30% inhibition cutoff value against wild-type SARS-CoV-2 were 57.2%, 98.6%, 97.8%, and 98.9% at points before and after the third dose, before and after the fourth dose, respectively among those receiving AZD1222 as the third dose. Frequencies were 31.9%, 99.3%, 98.9%, and 100% among those receiving BNT162b2 as the third dose, respectively. The seroconversion rates against B.1.1.529 [Omicron] were 76.1% and 90.2% (p-value 0.010) at 4 weeks after the third dose in those receiving AZD1222 and BNT162b2 as the third dose, respectively. After a booster with the mRNA vaccine, the seroconversion rates increased from 21.7 to 91.3% and from 30.4 to 91.3% in those receiving AZD1222 and BNT162b2 as the third dose, respectively. No serious safety concerns were found in this study. In conclusion, antibody responses waned over time regardless of the vaccine regimen. The booster dose of the vaccine elicited a humoral immune response against SARS-CoV-2 including SARS-CoV-2 variants of concern, including B.1.1.529 [Omicron], which was circulating during the study period. However, the results might not be extrapolated to other Omicron sublineages.

Minireview: Insights into anti-interferon-γ autoantibodies.

The association between the presence of anti-interferon-γ autoantibodies and the onset of immunodeficiency with intracellular infections has been clearly established. No standard regimen to control the production of these pathogenic autoantibodies, apart from antimicrobial therapy to eliminate infections, contributes to the medical burden of this syndrome, which sometimes has a fatal outcome. In this review, we summarize the findings on anti-interferon-γ autoantibodies to facilitate further research and to provide guidance for treatment strategies.

Cytotoxic and cytostatic effects of four Annonaceae plants on human cancer cell lines.

Several species of the Annonaceae plants have been used as complementary medicine for cancer-associated illnesses in some ethnic groups of northern Thailand. This study investigated the cytotoxic and cytostatic activity of methanolic extracts derived from the stems of these plants, including Uvaria longipes (Craib) L.L.Zhou, Y.C.F.Su & R.M.K.Saunders, Artabotrys burmanicus A.DC, Marsypopetalum modestum (Pierre) B.Xue & R.M.K.Saunders, and Dasymaschalon sp. Cell death induction of seven human cancer cell lines and cell cycle analyses were assessed by Annexin V and/or propidium iodide (PI) staining and analyzed by flow cytometry. Treatment of cancer cell lines with the extract of four Annonaceae plants resulted in various cytotoxic activities depending on cell type. The extract of U. longipes exhibited the highest cytotoxic activity capable of inducing cell death of several cancer cell lines, particularly against hepatocellular carcinoma cell lines (HepG2 and Hep3B). This extract was capable of inducing cell cycle arrest at the SubG1 phase. Phytochemical screening of all the extracts revealed the presence of alkaloids, sterols, tannins, anthraquinone glycoside, coumarin, and flavonoids. Determination of active compounds by high-performance liquid chromatography standards revealed bullatacin and asiminecin in all the extracts. The extract of Annonaceae stem or its compounds may provide an opportunity for the development of new therapies against cancer.

Neutralizing Activity of Anti-interferon-γ Autoantibodies in Adult-Onset Immunodeficiency Is Associated With Their Binding Domains.

Adult-onset immunodeficiency (AOID) with anti-interferon-γ (IFN-γ) autoantibodies (autoAbs) is an emerging immunodeficiency syndrome in Asian countries. The presence of neutralizing anti-IFN-γ autoAbs are significantly associated with severe disseminated opportunistic infections. However, the characteristics of the neutralizing antibodies in patients are poorly defined. To better understand the properties of the anti-IFN-γ autoAbs in patients with opportunistic infections, a simplified competitive-binding ELISA was developed. The domains recognized by anti-IFN-γ autoAbs were assessed based on their competition with commercial neutralizing mouse anti-IFN-γ monoclonal antibodies (mAbs). First, the binding affinity and neutralizing capacity of these mAbs (clones B27, B133.5, and MD-1) were characterized. Kinetic analysis and epitope binning using bio-layer interferometry showed the comparable binding affinity of these mAbs to full-length IFN-γ and to the adjacent binding region. These mAbs did not recognize the synthetic 20-mer peptides and inhibited IFN-γ-mediated functions differently. In a competitive-binding ELISA, the anti-IFN-γ autoAbs in AOID serum blocked B27, B133.5, and MD-1 mAb binding. This evidence suggested that the autoAbs that competed with neutralizing mouse anti-IFN-γ mAbs recognized a discontinuous epitope of homodimeric IFN-γ as these mAbs. The patient autoAbs that recognized the B27 epitope exhibited strong neutralizing activity that was determined by the functional analysis. Our results demonstrated the heterogeneity of the autoAbs against IFN-γ in AOID patients and the different patterns among individuals. These data expand upon the fundamental knowledge of neutralizing anti-IFN-γ autoAbs in AOID patients.

Characterization of anti-interferon-γ antibodies in HIV-negative immunodeficient patients infected with unusual intracellular microorganisms.

A major characteristic of immunodeficiency associated with life-threatening intracellular infection in adults is the presence of anti-interferon-γ antibodies. Although little is known about the mechanism underlying this syndrome, it is believed that the antibodies inhibit the activity of downstream signaling pathway of interferon-γ. In this study, the characteristics of these antibodies in patients who presented, or have a history of, intracellular infection and were positive to anti-interferon-γ antibodies were investigated. The antibodies exhibited mainly the IgG1 and the IgG4 subtypes and recognized the C-terminal of the interferon-γ linear epitope containing the KRKR motif, which is required for the biological activity of interferon-γ. The antibodies bound to recombinant interferon-γ with significantly lower avidity than antibodies to a recall antigen, tetanus toxoid, suggesting that the antibodies might have not undergone affinity maturation. The data from this study may provide fundamental information to better understand the properties of anti-interferon-γ antibodies, which can be useful for future studies. Impact statement An increase in the number of immunodeficient patients related to autoantibodies to interferon (IFN)-γ has been observed particularly in East Asian adults. These patients are often presented with opportunistic infections caused by intracellular pathogens, including non-tuberculous mycobacteria (NTM), Cryptococcus neoformans, Penicillium marneffei (now called Talaromyces marneffei), and non-typhoidal Salmonella spp. The mortality rate for this syndrome is relatively high with 32% patients dying at the median time of 25 months after diagnosis. Characterization of these autoantibodies may promote better understanding of the syndrome, an emerging health problem affecting East Asia populations and impeding their welfare and economic development.