30 years ago, researchers noticed that the capsid (VP1) gene of B19 parvovirus might encode a second protein, called "X", in an overlapping reading frame. Since then, experimental approaches failed to detect it. In contrast, sequence analyses can reliably predict whether a protein is expressed from an overlapping frame, provided that it is beneficial to the virus and thus under selection pressure. We used a dedicated software, Synplot2, to identify regions of VP1 likely to encode functional proteins in overlapping frames. Synplot2 detected the X open reading frame and confirmed it is under highly significant selection pressure. We discovered that the X protein is homologous to the ARF1 protein of human parvovirus 4, another suspected protein encoded in a frame overlapping VP1. These findings provide compelling evidence that the X protein must be expressed and functional. We predict that it contains a predicted transmembrane region. We found that the X frame contains a potential AUG start codon in parvovirus B19 and in all related species. Yet no currently known viral transcript has the potential to encode the X protein in a monocistronic fashion. Therefore, the X protein is probably expressed either from an unmapped monocistronic mRNA, or translated by a non-canonical mechanism from the VP1 mRNA or from a short transcript, R3, which has no currently known function. Finally, Synplot2 also detected proteins likely to be expressed from a frame overlapping VP1 in species distantly related to parvovirus B19: porcine parvovirus 2 and bovine parvovirus 3.

To understand the evolution of the human norovirus GII.P6-GII.6 and GII.P7-GII.6 strains, we analyzed both the RdRp region and VP1 gene in globally collected strains using authentic bioinformatics technologies. A common ancestor of the P6- and P7-type RdRp region emerged approximately 50 years ago and a common ancestor of the P6- and P7-type VP1 gene emerged approximately 110 years ago. Subsequently, the RdRp region and VP1 gene evolved. Moreover, the evolutionary rates were significantly faster for the P6-type RdRp region and VP1 gene than the P7-type RdRp region and VP1 genes. Large genetic divergence was observed in the P7-type RdRp region and VP1 gene compared with the P6-type RdRp region and VP1 gene. The phylodynamics of the RdRp region and VP1 gene fluctuated after the year 2000. Positive selection sites in VP1 proteins were located in the antigenicity-related protruding 2 domain, and these sites overlapped with conformational epitopes. These results suggest that the GII.6 VP1 gene and VP1 proteins evolved uniquely due to recombination between the P6- and P7-type RdRp regions in the HuNoV GII.P6-GII.6 and GII.P7-GII.6 virus strains.

The Chinese honeybee (Apis cerana cerana) sacbrood virus (CSBV) causes death of larvae and colony collapse, and could damage the beekeeping industry in China. We sequenced complete genomes of CSBV strains derived from the Maerkang area, Wenjiang area, and Wanyuan area of Sichuan province of China. The genome length of CSBV strains from Sichuan was 8863bp, and it contained one complete Open Reading Frame of a gene with 8544 bp that encoded a protein with 2848 amino acids. The (G+C) % and (A+T) % composition ranged from 40.6 to 40.7 and 59.3 to 59.4, respectively. A phylogenetic tree was constructed using the three CSBV strains and previously reported SBV and CSBV sequences from other regions. We found that viral strains clustered based on their region of origin and host species. The genetic sequences of the CSBV strain from Maerkang were 98.7% and 99.6% similar to CSBV strains from Wanyuan and Wenjiang, respectively. In addition, CSBV from Maerkang had 88.4%-95.2% sequence similarity to previously published genomes of CSBV or SBV from other areas. The VP1 gene sequenced in our study had a 43 bp deletion compared to VP1 sequences of CSBV from other regions in Asia. We detected 10 antigenic determinants on the VP1 protein of CSBV form Aba. Our study provides new insight into the diversity of CSBV strains in China and may help with identifying methods to prevent infection of honeybee colonies.

The JC polyomavirus virus (JCPyV) affects more than 80% of the human population in their early life stage. It mainly affects immunocompromised individuals where virus replication in oligodendrocytes and astrocytes may lead to fatal progressive multifocal encephalopathy (PML). Virus protein 1 (VP1) is one of the major structural proteins of the viral capsid, responsible for keeping the virus alive in the gastrointestinal and urinary tracts. VP1 is often targeted for antiviral drug and vaccine development. Similarly, this study implied immunoinformatics and molecular dynamics simulation-based approaches to design a multi-epitope subunit vaccine targeting JCPyV. The VP1 protein epitopic sequences, which are highly conserved, were used to build the vaccine. This designed vaccine includes two adjuvants, five HTL epitopes, six CTL epitopes, and two linear BCL epitopes to stimulate cellular, humoral, and innate immune responses against JCPyV. Furthermore, molecular docking and molecular dynamics simulation (100ns) studies were used to examine the interaction and stability of the vaccine protein with TLR4. Trajectory analysis showed that the vaccine and TLR4 receptor form a stable complex with the vaccine protein. Overall, this study contributed to the path of vaccine development against JCPyV and may prevent PML from happening. However, this study needs experimental validation to conclude our findings.