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Coronaviruses are a large family of important pathogens that cause human and animal diseases. At the end of 2019, a pneumonia epidemic caused by a novel coronavirus brought attention to coronaviruses. Exploring the interaction between the virus and its receptor will be helpful in developing preventive vaccines and therapeutic drugs. The coronavirus spike protein (S) plays an important role in both binding to receptors on host cells and fusion of the viral membrane with the host cell membrane. This review introduces the structure and function of the S protein and its receptor, focusing on the binding mode and binding region of both.

Bartonella species are emerging human pathogens. Bats are known to carry diverse Bartonella species, some of which are capable of infecting humans. However, as the second largest mammalian group by a number of species, the role of bats as the reservoirs of Bartonella species is not fully explored, in term of their species diversity and worldwide distribution. China, especially Northern China, harbors a number of endemic insectivorous bat species; however, to our knowledge, there are not yet studies about Bartonella in bats in China. The aim of the study was to investigate the prevalence and genetic diversity of Bartonella species in bats in Northern China. Bartonella species were detected by PCR amplification of gltA gene in 25.2% (27/107) bats in Mengyin County, Shandong Province of China, including 1/3 Rhinolophus ferrumequinum, 2/10 Rhinolophus pusillus, 9/16 Myotis fimbriatus, 1/5 Myotis ricketti, 14/58 Myotis pequinius. Phylogenetic analysis showed that Bartonella species detected in bats in this study clustered into ten groups, and some might be novel Bartonella species. An association between Bartonella species and bat species was demonstrated and co-infection with different Bartonella species in a single bat was also observed. Our findings expanded our knowledge on the genetic diversity of Bartonella in bats, and shed light on the ecology of bat-borne Bartonella species.

Hand, foot, and mouth disease (HFMD), which has led to millions of attacks and several outbreaks across the world and become more predominant in Asia-Pacific Region, especially in Mainland China, is caused by several Human Enteroviruses including new enterovirus, coxsakievirus and echovirus. In recent years, much research has focused on the epidemiological characteristics of HFMD. In this article, multiple characteristics of HFMD such as basic epidemiology, etiology and molecular epidemiology; influencing factors; detection; and surveillance are reviewed, as these can be help protect high risks groups, prevalence prediction and policy making for disease prevention.

We identified Candidatus Borrelia fainii, a human pathogenic bacterium causing New World relapsing fever in a Myotis bat in eastern China. This finding expands knowledge about the geographic distribution of Borrelia spp. and the potential for infection with New World relapsing fever in China.

Background: Enterovirus 71 (EV71) is the main pathogen that causes severe hand, foot, and mouth disease with fatal neurological complications. However, its neurovirulence mechanism is still unclear. Candidate virulence sites were screened out at structural protein VP1, but the function of these candidate virulence sites remains unclear. Several studies have shown that autophagy is associated with viral replication. However, the relationship between VP1 and autophagy in human neurons has not been studied. Methods: A recombinant virus—SDLY107-VP1, obtained by replacing the VP1 full-length gene of the SDLY107 strain with the VP1 full-length gene of the attenuated strain SDJN2015-01—was constructed and tested for replication and virulence. We then tested the effect of the recombinant virus on autophagy in nerve cells. The effect of autophagy on virus replication was detected by western blot and plaque test. Finally, the changes of mTOR signaling molecules during EV71 infection and the effect of mTOR on virus replication at the RNA level were detected. Results: Viral recombination triggered virulence attenuation. The replication ability of recombinant virus SDLY107-VP1 was significantly weaker than that of the parent strain SDLY107. The SDLY107 strain could inhibit autophagic flux and led to accumulation of autophagosomes, while the SDLY107-VP1 strain could not cause autophagosome accumulation. The synthesis of EV71 RNA was inhibited by inhibiting mTOR. Conclusions: Replacement of VP1 weakened the replication ability of virulent strains and reduced the level of autophagy in nerve cells. This autophagy facilitates the replication of virulent strains in nerve cells. VP1 is an important neurovirulence determinant of EV71, which affects virus replication by regulating cell autophagy. mTOR is a key molecule in this type of autophagy.

Background Severe fever with thrombocytopenia syndrome virus (SFTSV) is a novel tick-borne phlebovirus, which is listed in the most dangerous pathogens by the World Health Organization, and has 12-30% fatality rates. SFTSV antibodies were reported in minks that experienced abortion or reproductive failure. The aim of this study was to determine whether SFTSV infection causes an adverse pregnancy outcome in the fetus using a pregnant mouse model. Methodology/Principal findings We found SFTSV in the fetus after infection in pregnant mice, and some dams showed adverse pregnancy outcomes after infection with SFTSV including placental damage, fetal reabsorption, and fetal intrauterine growth restriction (IUGR). SFTSV had obvious tropism characteristics in the placenta, especially in the labyrinth. In early-gestation, pregnant mice infected with SFTSV had fetal IUGR and a high viral load in the fetus. The virus widely spread in infected fetuses, including the hindbrain, thymus, heart, spinal cord, and liver. Conclusions Our study demonstrated that SFTSV was vertically transmitted to the fetus through the placental barrier of immunocompetent mice, and resulted in adverse pregnancy outcomes.

Background To increase understanding of human bacterial and parasitic pathogens in bats, we investigated the prevalence of Babesia spp., Rickettsia spp., Anaplasma spp. and Coxiella burnetii in bats from China. Methods Bats were captured from Mengyin County, Shandong Province of China using nets. DNA was extracted from the blood and spleen of bats for molecular detection of Babesia spp., Rickettsia spp., Anaplasma spp. and Coxiella burnetii with specific primers for each species. Results A total of 146 spleen samples and 107 blood samples of insectivorous bats, which belonged to 6 species within two families, were collected from Mengyin County, Shandong Province of China. We found that two Eptesicus serotinus (2/15, 13.3%) were positive for Babesia vesperuginis . We were unable to detect genomic sequences for Rickettsia spp., Anaplasma spp. and Coxiella burnetii . Conclusions To our knowledge, our study showed for the first time the presence of Babesia vesperuginis in Eptesicus serotinus collected from China, suggesting that Babesia vesperuginis has a broad host species and geographical distribution.

Apparently these Anaplasma species should be a single species according to the criterion that a bacterial species must have at least 99% 16S rRNA gene homology,2 and the natural hosts of the novel Anaplasma species include goat, cattle, deer, and serow.3,4 Li and colleagues isolated \"A capra\" from human beings and goats living in a forest area in the northeast China.

Hemorrhagic fever with renal syndrome (HFRS) was considered to be transmitted by Apodemus agrarius and Rattus norvegicus , the principal animal hosts of Hantaan virus and Seoul virus, respectively. The aim of this study is to determine the correlation of HFRS incidence with capture rate and hantavirus infection rate of rodent species in Qingdao City, China. We collected HFRS patients’ information and captured field and residential rodents in Qingdao City, China from 2010 to 2014. The correlations of HFRS incidence to rodent capture rate and hantavirus infection rate of rodents were analyzed statistically. The main findings of this study are that the high HFRS incidence (19.3/100,000) is correlated to the capture rate of field Mus musculus (p = 0.011, r = 0.037); but surprisingly it did not correlated to the capture rate of the principal rodent hosts Apodemus agrarius and Rattus norvegicus and the hantavirus infection rate of these rodent species in the field or residential area. These novel findings suggest that Mus musculus, a nontraditional animal host of hantavirus may play an important role in hantavirus transmission in Qingdao City.

BACKGROUND: Hand, foot and mouth diseases (HFMD) caused by enterovirus 71(EV71) presents a broad spectrum of clinical manifestations ranging from mild febrile disease to fatal neurolocal disease. However, the mechanism of virulence is unknown. METHODS: We isolated 6 strains of EV71 from HFMD patients with or without neurological symptoms, and sequenced the whole genomes of the viruses to reveal the virulence factors of EV71. RESULTS: Phylogenetic tree based on VP1 region showed that all six strains clustered into C4a of C4 sub-genotype. In the complete polypeptide, 298 positions were found to be variable in all strains, and three of these positions (Valᴾ⁸¹⁴/Ileᴾ⁸¹⁴in VP1, Valᴾ¹¹⁴⁸/Ileᴾ¹¹⁴⁸in 3A and Alaᴾ¹⁷²⁸/Cysᴾ¹⁷²⁸/Valᴾ¹⁷²⁸in 3C) were conserved among the strains with neurovirulence, but variable in strains without neurovirulence. In the 5′-UTR region, it showed that the first 10 nucleotides were mostly conserved, however from the 11th nucleotide, nucleotide insertions and deletions were quite common. The secondary structure prediction of 5′-UTR sequences showed that two of three strains without neurovirulence (SDLY11 and SDLY48) were almost the same, and all strains with neurovirulence (SDLY96, SDLY107 and SDLY153) were different from each other. SDLY107 (a fatal strain) was found different from other strains on four positions (Cᴾ²⁴¹/Tᴾ²⁴¹, Aᴾ⁵⁷¹/Tᴾ⁵⁷¹, Cᴾ⁵⁷⁹/Tᴾ⁵⁷⁹in 5′-UTR and Tᴾ⁷³³⁵/Cᴾ⁷³³⁵in 3′-UTR). CONCLUSIONS: The three positions (Valᴾ⁸¹⁴/Ileᴾ⁸¹⁴in VP1, Valᴾ¹¹⁴⁸/Ileᴾ¹¹⁴⁸in 3A and Alaᴾ¹⁷²⁸/Cysᴾ¹⁷²⁸/Valᴾ¹⁷²⁸in 3C), were different between two phenotypes. These suggested that the three positions might be potential virulent positions. And the three varied positions were also found to be conserved in strains with neurovirulence, and variable in strains without neurovirulence. These might reveal that the conservation of two of the three positions or the three together were specific for the strains with neurovirulence. Varation of secondary structure of 5′-UTR, might be correlated to the changes of viral virulence. SDLY107 (a fatal strain) was found different from other strains on four positions, these positions might be related with death.