Pneumoconiosis is a common occupational disease that can worsen with accompanying infection. Torque teno virus (TTV) is a prevalent human virus with multiple genotypes that can chronically and persistently infect individuals. However, the prevalence of TTV in pneumoconiosis patients is still unclear. This research aims to detect the presence and prevalence of TTV in the alveolar lavage fluid of pneumoconiosis patients in the Hunan Province of China using PCR. As a result, a 65.5% positive rate (19 out of 29) of TTV was detected. The TTV detection rate varies among different stages of silicosis and different pneumoconiosis patient ages. Nine novel TTV genomes ranging in size from 3719 to 3908 nt, named TTV HNPP1, HNPP2, HNPP3, HNPP4, HNPP5, HNPP6-1, HNPP6-2, HNPP7-1 and HNPP7-2, were identified. A genomic comparison and phylogenetic analysis indicated that these nine TTVs represent five different species with high genetic diversity which belong to the genus Alphatorquevirus. HNPP6-1 and HNPP6-2 belong to TTV3, HNPP5 belongs to TTV13, HNPP1 belongs to TTV24, HNPP4 belongs to TTV20, and the others belong to TTV19. The genomes of TTV HNPP1, HNPP6-1, and HNPP6-2 contain three putative open reading frames (ORFs) coding for proteins, ORF1, ORF2, and ORF3, while the other six TTV genomes contain two ORFs coding for proteins, ORF1 and ORF2. These results provide the first description of TTV epidemiology in pneumoconiosis patients in China. The newly identified TTV genome sequences reveal the high genetic diversity of TTV in pneumoconiosis patients and could contribute to a deeper understanding of TTV retention and infection in humans.

Coronavirus pandemics have become a huge threat to the public health worldwide in the recent decades. Typically, SARS-CoV caused SARS pandemic in 2003 and SARS-CoV-2 caused the COVID-19 pandemic recently. Both viruses have been reported to originate from bats. Thus, direct or indirect interspecies transmission from bats to humans is required for the viruses to cause pandemics. Receptor utilization is a key factor determining the host range of viruses which is critical to the interspecies transmission. Angiotensin converting enzyme 2 (ACE2) is the receptor of both SARS-CoV and SARS-CoV-2, but only ACE2s of certain animals can be utilized by the viruses. Here, we employed pseudovirus cell-entry assay to evaluate the receptor-utilizing capability of ACE2s of 20 animals by the two viruses and found that SARS-CoV-2 utilized less ACE2s than SARS-CoV, indicating a narrower host range of SARS-CoV-2. Meanwhile, pangolin CoV, another SARS-related coronavirus highly homologous to SARS-CoV-2 in its genome, yet showed similar ACE2 utilization profile with SARS-CoV rather than SARS-CoV-2. To clarify the mechanism underlying the receptor utilization, we compared the amino acid sequences of the 20 ACE2s and found 5 amino acid residues potentially critical for ACE2 utilization, including the N-terminal 20 ^th and 42 ^nd amino acids that may determine the different receptor utilization of SARS-CoV, SARS-CoV-2 and pangolin CoV. Our studies promote the understanding of receptor utilization of pandemic coronaviruses, potentially contributing to the virus tracing, intermediate host screening and epidemic prevention for pathogenic coronaviruses.

Enterovirus alphacoxsackie (EV-A) is a highly diverse viral species containing at least 25 serotypes with diverse biological and clinical characteristics. EV-A can cause diseases ranging from asymptomatic infections to severe neurological disorders, as well as mucocutaneous diseases such as hand, foot, and mouth disease. 2A, a cysteine protease expressed by EV-A, plays critical roles in virus–host interactions. Although 2A orthologs of different EV-A serotypes share consistent protease-catalytic motifs and cleavage patterns, they show functional diversity in interacting with cellular proteins, probably due to distinct protease-independent activities determined by the single amino acid polymorphisms (SAPs) among different 2A orthologs. However, routine sequence alignment and phylogenetic analysis can hardly identify the key SAP sites (kSAPs) contributing to the functional variance, mainly due to the high conservation of the proteins and the unequal weight of SAPs in determining protein function. Herein, we developed Single Amino Acid Polymorphism Statistics (SAAPS), an information-entropy (IE)-based algorithmic pipeline, to identify the functional kSAPs of EV-A 2A. The core principle of the algorithm is that the IE of the kSAPs can be neither too low (highly conserved sites not leading to variance) nor too high (random neutral mutations). Using SAAPS, we identified 56 kSAPs from 2A of 25 EV-A serotypes. Based on the kSAPs, the 2As can be clustered into three major groups with a few outliers, which was distinct from the clustering generated by phylogenetic analysis using the whole amino acid sequences. Functional verification with transcriptomic profiles of HEK-293T cells expressing different 2A variants revealed closer alignment of kSAP clustering than phylogenetic clustering. Notably, EV-A89, an outlier identified by kSAP clustering but not phylogenetic clustering, showed a unique expression pattern with an altered shift in the molecular weight, which suggested that it was related to three SAPs identified by SAAPS. This study presents SAAPS as a useful tool for prioritizing functionally relevant SAPs to guide mechanistic discovery and can be applied to highly conserved proteins like EV-A 2A.