Laboratory detection of strongyloidiasis: IgG‐, IgG4‐ and IgE‐ELISAs and cross‐reactivity with lymphatic filariasis

Enzyme‐linked immunosorbent assays (ELISAs) were developed for the detection of IgG, IgG₄ and IgE antibodies against Strongyloides stercoralis. A commercial ELISA (IVD Research, USA) was also used, and the sensitivities and specificities of the four assays were determined. Serum samples from 26 patients with S. stercoralis infection and 55 patients with other infections or no infection were analysed. Sensitivities of the IgG₄, IgG, IgE and IgG (IVD) assays were 76·9%, 84·6%, 7·7% and 84·6%, respectively, while the specificities were 92·7%, 81·8%, 100% and 83·6%, respectively. If filariasis samples were excluded, the specificities of the IgG₄‐ELISA and both IgG‐ELISAs increased to 100% and 98%, respectively. A significant positive correlation was observed between IgG‐ and IgG₄‐ELISAs (r = 0·4828; P = 0·0125). IgG‐ and IgG‐ (IVD) ELISAs (r = 0·309) were positively correlated, but was not significant (P = 0·124). Meanwhile there was no correlation between IgG₄‐ and IgG‐ (IVD) ELISAs (r = 0·0042; P = 0·8294). Sera from brugian filariasis patients showed weak, positive correlation between the titres of antifilarial IgG₄ and the optical densities of anti‐Strongyloides IgG₄‐ELISA (r = 0·4544, P = 0·0294). In conclusion, the detection of both anti‐Strongyloides IgG₄ and IgG antibodies could improve the serodiagnosis of human strongyloidiasis. Furthermore, patients from lymphatic filariasis endemic areas who are serologically diagnosed with strongyloidiasis should also be tested for filariasis.     

IL‐28B (IFN‐λ3) and IFN‐α synergistically inhibit HCV replication

Genetic variation in the IL‐28B (interleukin‐28B; interferon lambda 3) region has been associated with sustained virological response (SVR) rates in patients with chronic hepatitis C treated with peginterferon‐α and ribavirin. However, the mechanisms by which polymorphisms in the IL‐28B gene region affect host antiviral responses are not well understood. Using the HCV 1b and 2a replicon system, we compared the effects of IFN‐λs and IFN‐α on HCV RNA replication. The anti‐HCV effect of IFN‐λ3 and IFN‐α in combination was also assessed. Changes in gene expression induced by IFN‐λ3 and IFN‐α were compared using cDNA microarray analysis. IFN‐λs at concentrations of 1 ng/mL or more exhibited concentration‐ and time‐dependent HCV inhibition. In combination, IFN‐λ3 and IFN‐α had a synergistic anti‐HCV effect; however , no synergistic enhancement was observed for interferon‐stimulated response element (ISRE) activity or upregulation of interferon ‐ stimulated genes (ISGs). With respect to the time course of ISG upregulation, the peak of IFN‐λ3‐induced gene expression occurred later and lasted longer than that induced by IFN‐α. In addition, although the genes upregulated by IFN‐α and IFN‐λ3 were similar to microarray analysis, interferon‐stimulated gene expression appeared early and was prolonged by combined administration of these two IFNs. In conclusion, IFN‐α and IFN‐λ3 in combination showed synergistic anti‐HCV activity in vitro. Differences in time‐dependent upregulation of these genes might contribute to the synergistic antiviral activity.     

Role of IFN‐λs,IFN‐λs related genes and the DEPDC5 gene in Hepatitis B virus‐related liver disease

Recent studies have associated genetic variation near the interleukin 28B (IL28B/IFN‐λ3) gene with natural clearance of the hepatitis C virus (HCV) infection, and a common variant in the DEP domain containing 5 (DEPDC5) locus on chromosome 22 has been shown to affect susceptibility to hepatocellular carcinoma (HCC) in Japanese individuals with chronic HCV infection. This study was conducted to determine whether polymorphisms near or in interferon‐lambda (IFN‐λs) genes and their receptor genes such as interleukin 28 receptor, alpha (IL28RA) and interleukin 10 receptor, beta (IL10RB) as well as p21_activated kinases 4 (PAK4) and iron/zinc purple acid phosphatase‐like protein (PAPL), which are locate upstream of IFN‐λs, and lastly the DEPDC5 gene are associated with hepatitis B virus‐related liver disease in Han Chinese. The study subjects included 507 normal healthy controls, 350 individuals with natural clearance of HBV and 792 HBV‐infected patients. The patients were categorized into 157 inactive carriers (Case I), 216 active carriers (Case II), 111 cirrhotics (Case III) and 308 HCC patients (Case IV) subgroups. Seven single nucleotide polymorphisms (SNPs) were genotyped using the Matrix‐assisted Laser Desorption/Ionisation mass spectrometric (MALDI‐TOF MS) SNP genotyping assay. Rs423058 upstream of PAPL, rs2834167 in IL10RB and rs1012068 in DEPDC5 were associated with chronic HBV status, HBV natural clearance and the presence of HCC (P = 0.0004–0.024), respectively. PAPL, IL10RB and DEPDC5 polymorphisms have an impact on progression of HBV‐related liver disease. However, IFN‐λs genes as a tool to differentiate between different clinical courses of HBV infection were not useful in the Han Chinese population.