Neuronal infection is a major pathogenetic mechanism and cause of fatalities in human acute Nipah virus encephalitis.

OBJECTIVES: Acute Nipah (NiV) encephalitis is characterised by a dual pathogenetic mechanism of neuroglial infection and ischaemia-microinfarction associated with vasculitis-induced thrombotic occlusion. We investigated the contributions of these two mechanisms in fatal cases. MATERIALS AND METHODS: We analysed brain tissues (cerebrum, brainstem and cerebellum) from 15 autopsies using light microscopy, immunohistochemistry (IHC), in situ hybridisation and quantitative methods. RESULTS: Three types of discrete plaque-like parenchymal lesions were identified: Type 1 with neuroglial IHC positivity for viral antigens and minimal or no necrosis; Type 2 with neuroglial immunopositivity and necrosis; and Type 3 with necrosis but no viral antigens. Most viral antigen/RNA-positive cells were neurons. Cerebral glial immunopositivity was rare, suggesting that microinfarction played a more important role in white matter injury. Type 1 lesions were also detected in the brainstem and cerebellum, but the differences between cerebral cortex and these two regions were not statistically significant. In the cerebral cortex, Type 1 lesions overwhelmingly predominated, and only 14% Type 1 vs 69% Type 2 lesions were associated with thrombosis. This suggests that neuronal infection as a mechanism of pathogenesis was more important than microinfarction, both in general and in Type 1 lesions in particular. Between the 'early' group (<8-day fever) and the 'late' group (≥8-day fever), there was a decrease of Type 1 and Type 2 lesions with a concomitant increase of Type 3 lesions, suggesting the latter possibly represented late-stage microinfarction and/or neuronal infection. CONCLUSION: Neuronal infection appears to play a more important role than vasculopathy-induced microinfarction in acute NiV encephalitis.

Universal Primers for Detection and Sequencing of Hepatitis B Virus Genomes across Genotypes A to G.

Hepatitis B virus (HBV) has been divided into 10 genotypes, A to J, based on an 8% nucleotide sequence divergence between genotypes. The conventional practice of using a single set of primers to amplify a near-complete HBV genome is hampered by its low analytical sensitivity. The current practice of using overlapping conserved primer sets to amplify a complete HBV genome in a clinical sample is limited by the lack of pan-primers to detect all HBV genotypes. In this study, we designed six highly conserved, overlapping primer sets to cover the complete HBV genome. We based our design on the sequences of 5,154 HBV genomes of genotypes A to I downloaded from the GenBank nucleotide database. These primer sets were tested on 126 plasma samples from Malaysia, containing genotypes A to D and with viral loads ranging from 20 to >79,780,000 IU/ml. The overall success rates for PCR amplification and sequencing were >96% and >94%, respectively. Similarly, there was 100% amplification and sequencing success when the primer sets were tested on an HBV reference panel of genotypes A to G. Thus, we have established primer sets that gave a high analytical sensitivity for PCR-based detection of HBV and a high rate of sequencing success for HBV genomes in most of the viral genotypes, if not all, without prior known sequence data for the particular genotype/genome.