TaqMan real-time PCR assay for relative quantification of white spot syndrome virus infection in Penaeus monodon Fabricius exposed to ammonia.

White spot disease is caused by a highly virulent pathogen, the white spot syndrome virus (WSSV). The disease is usually triggered by changes in environmental parameters causing severe losses to the shrimp industry. This study was undertaken to quantify the relative WSSV load in shrimp exposed to ammonia, using a TaqMan-based real-time PCR, and their subsequent susceptibility to WSSV. Shrimp were exposed to different levels of total ammonia nitrogen (TAN) (8.1, 3.8 and 1.1 mg L⁻¹) for 10 days and challenged with WSSV by feeding WSSV-positive shrimp. WSSV was detected simultaneously in haemolymph, gills and pereopods at four hours post-infection. The TaqMan real-time PCR assay showed a highly dynamic detection limit that spanned over 6 log10 concentrations of DNA and high reproducibility (standard deviation 0.33-1.42) and small correlation of variability (CV) (1.89-3.85%). Shrimp exposed to ammonia had significantly higher (P < 0.01) WSSV load compared to the positive control, which was not exposed to ammonia. Shrimp exposed to 8.1 mg L⁻¹ of TAN had the highest (P < 0.01) WSSV load in all three organs in comparison with those exposed to 3.8 and 1.1 mg L⁻¹ of TAN. However, haemolymph had significantly higher (P < 0.01) viral load compared to the gills and pereopods. Results showed that shrimp exposed to ammonia levels as low as 1.1 mg L⁻¹ (TAN) had increased susceptibility to WSSV.

Frequency of Helicobacter pylori infection in dyspeptic patients in Libya.

OBJECTIVE: Helicobacter pylori infection is a very common infection worldwide particularly in the developing countries. The organism plays an important role in peptic ulcer diseases. The aim of the study was to detect and correlate the prevalence of Helicobacter pylori with such diseases and to evaluate the histopathological grading of gastritis. METHODS: One hundred thirty two patients of 15-83 years of age (average 38) attending the endoscopy unit at the El-Jamahiria Hospital, Binghazi, Libya, mainly complaining from epigastric pain were randomly selected. Three antral biopsies for rapid urease test, direct smear stain and histology together with serum samples were obtained from each patient. Grading of gastritis and the presence of Helicobacter pylori was scored according to the Sydney system. RESULTS: Patients were considered infected when 2 of the biopsy-based tests were positive. Helicobacter pylori was detected in 108 (82%) of 132 patients examined (86% by rapid urease test, 77% by direct smear stain, 95% by histology). The endoscopic findings revealed that 77 (77%) of 100 patients with non-ulcer dyspepsia, 26 (96%) of 27 with duodenal ulcer, 4 (100%) of 4 with gastric ulcer and in one patient with gastric cancer were Helicobacter pylori positive. The enzyme-linked immunosorbent assay test showed 94% sensitivity and 88% specificity. Histopathological sections from the majority of duodenal ulcer and gastric ulcer patients revealed higher grade (II and III) of gastritis than non-ulcer dyspepsia patients. CONCLUSION: Helicobacter pylori infection is significantly correlated with peptic ulcer diseases than with non-ulcer dyspepsia. Patients with duodenal ulcer and gastric ulcer had a significantly higher grade of gastritis than patients with non-ulcer dyspepsia.