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Pepper plants (Capsicum annuum) with severe leaf curl symptoms were collected in 2013 from Bangalore, Karnataka, India. The detection results showed a co-infection between the tomato leaf curl Joydebpur virus (ToLCJoV) and tomato leaf curl Bangladesh betasatellite (ToLCBDB) through the sequencing analysis of PCR amplicons. To pinpoint the molecular mechanism of this uncommon combination, infectious clones of ToLCJoV and two different betasatellites—ToLCBDB and tomato leaf curl Joydebpur betasatellite (ToLCJoB)—were constructed and tested for their infectivity in Nicotiana benthamiana. Together, we conducted various combined agroinoculation studies to compare the interaction of ToLCJoV with non-cognate and cognate betasatellites. The natural non-cognate interaction between ToLCJoV and ToLCBDB showed severe symptoms compared to the mild symptoms of a cognate combination (ToLCJoV × ToLCJoB) in infected plants. A sequence comparison among betasatellites and their helper virus wasperformed and the iteron resemblances in ToLCBDB as well as ToLCJoB clones were processed. Mutant betasatellites that comprised iteron modifications revealed that changes in iteron sequences could disturb the transreplication process between betasatellites and their helper virus. Our study might provide an important consideration for determining the efficiency of transreplication activity between betasatellites and their helper virus. [ABSTRACT FROM AUTHOR]

Hepatitis E virus (HEV) infection in pregnant women has a high incidence of developing fulminant hepatic failure (FHF) with significant mortality. Multiple amino acid changes in genotype 1 HEV (HEV-1) are reportedly linked to FHF clinical cases, but experimental confirmation of the roles of these changes in FHF is lacking. By utilizing the HEV-1 indicator replicon and infectious clone, we generated 11 HEV-1 single mutants, each with an individual mutation, and investigated the effect of these mutations on HEV replication and infection in human liver cells. We demonstrated that most of the mutations actually impaired HEV-1 replication efficiency compared with the wild type (WT), likely due to altered physicochemical properties and structural conformations. However, two mutations, A317T and V1120I, significantly increased HEV-1 replication. Notably, these two mutations simultaneously occurred in 100% of 21 HEV-1 variants from patients with FHF in Bangladesh. We further created an HEV-1 A317T/V1120I double mutant and found that it greatly enhanced HEV replication, which may explain the rapid viral replication and severe disease. Furthermore, we tested the effect of these FHF-associated mutations on genotype 3 HEV (HEV-3) replication and found that all the mutants had a reduced level of replication ability and infectivity, which is not unexpected due to distinct infection patterns between HEV-1 and HEV-3. Additionally, we demonstrated that these FHF-associated mutations do not appear to alter their sensitivity to ribavirin (RBV), suggesting that ribavirin remains a viable option for antiviral therapy for patients with FHF. The results have important implications for understanding the mechanism of HEV-1-associated FHF. [ABSTRACT FROM AUTHOR]

Chilli leaf curl virus is responsible for inducing leaf curl disease in Chili (Capsicum annum L.), with whitefly (Bemisia tabaci) serving as the vector for transmission. Chili leaf samples with leaf curl symptoms were collected from Guntur, Andhra Pradesh, India. PCR-based detection screened for begomoviral infection and betasatellite in the collected samples. In this study, we have characterized tomato leaf curl Bangladesh betasatellite (ToLCBB) (OQ184745) using universal betasatellite primers. Partial dimer constructs were developed using the betasatellite and the DNA A genome of the chilli leaf curl Ahmedabad virus (ChiLCAV) (MW316419) in pCAMBIA 1302 vector. Both the constructs were mobilized separately into the Agrobacterium strain LBA4404, followed by agroinfiltration into healthy chili plants. Plants co-infiltrated with DNA A and betasatellite dimers exhibited symptoms after 21 days of infiltration, whereas plants infiltrated separately with the partial dimer constructs did not display any symptoms. Prominent symptoms include upward curling, thickening of stem ribs and stunted plant growth. Chili plants infiltrated with the infectious clones of ChiLCAV + ToLCBB and ChiLCAV alone showed positive amplification with ChiLCAV-specific and betasatellite primers. In contrast, plants infiltrated with ToLCBB partial dimer construct did not show any amplification with betasatellite primers. ChiLCAV DNA A titer accumulation was further quantified with qPCR and we observed that there is a significant increase (p < 0.0001) in the accumulation level with ChiLCAV + ToLCBB construct when compared to the ChiLCAV construct alone. Thus, this study highlights the pathogenesis of leaf curl disease in C. annuum caused by the begomovirus complex of ChiLCAV and its associated betasatellite ToLCBB. • The most devastating leaf curl disease of the chili plant is caused by begomovirus. • Chili plants infiltrated with chilli leaf curl Ahamedabad virus (ChiLCAV) + tomato leaf curl Bangaldesh betasatellite (ToLCBB) showed symptoms. • Plants infiltrated with ToLCBB partial dimer construct didn't show any symptoms. • Viral titre accumulation was increased in the chili plants infiltrated with ChiLCAV + ToLCBB constructs. • This highlights the significance of ToLCBB in infecting and producing symptoms. [ABSTRACT FROM AUTHOR]