2018 Vol.33(2)
Baculoviruses have been used as biocontrol agents against insect pests and also exploited in therapeutic strategies and protein expression. The successful primary infection of baculoviruses in insect host is largely dependent on a family of membrane resident proteins, so-called per os infectivity factors (PIFs), which is likely to play an important role in virus entry into midgut epithelial cells of susceptible insect larvae. In this issue, George Alliwa Makalliwa et al. investigated the functional roles of PIF1, 2, and 3 using PIF-replaced viruses. They found that only PIF3 replacement showed the formation of PIF complex and retained partial oral infectivity, while substitution of either PIF1 or PIF2 inhibited the formation of PIF complex and oral infectivity. These results highlighted that the specificity of PIFs is quite high and the PIF complex is essential for the oral infectivity. The cover is modified from a transmission electron microscopy image of occlusion bodies from PIF3-replaced recombinant Helicoverpa armigera nucleopolyhedrovirus (kindly provided by George Alliwa Makalliwa and Zhihong Hu) with pseudo-color.
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The Regulation of cGAS
2018, 33(2): 117 doi: 10.1007/s12250-018-0005-6
Received: 28 August 2017
Accepted: 30 November 2017
Published: 15 March 2018
The cGAS-MITA pathway of cytosolic DNA sensing plays essential roles in immune response against pathogens that contain DNA or with DNA production in their life cycles. The cGAS-MITA pathway also detects leaked or aberrant accumulated self DNA in the cytoplasm under certain pathological conditions, such as virus induced cell death, DNA damage, mitochondria damage, gene mutations, which results in autoimmune diseases. Therefore, the cGAS-MITA pathway must be tightly controlled to ensure proper immune response against pathogens and to avoid autoimmune diseases. The regulation of cGAS-MITA pathway at MITA-level have been extensively explored and reviewed elsewhere, here we provide a summary and perspective on recent advances in understanding of the cGAS regulation.
Recent Advances in Animal Models of Zika Virus Infection
2018, 33(2): 125 doi: 10.1007/s12250-018-0007-4
Received: 12 June 2017
Accepted: 22 November 2017
Published: 14 March 2018
An infection by Zika virus (ZIKV), a mosquito-borne flavivirus, broke out in South American regions in 2015, and recently showed a tendency of spreading to North America and even worldwide. ZIKV was first detected in 1947 and only 14 human infection cases were reported until 2007. This virus was previously observed to cause only mild flu-like symptoms. However, recent ZIKV infections might be responsible for the increasing cases of neurological disorders such as GuillainBarre′ syndrome and congenital defects, including newborn microcephaly. Therefore, researchers have established several animal models to study ZIKV transmission and pathogenesis, and test therapeutic candidates. This review mainly summarizes the reported animal models of ZIKV infection, including mice and non-human primates.
A Highly Pathogenic Strain of Porcine Deltacoronavirus Caused Watery Diarrhea in Newborn Piglets
2018, 33(2): 131 doi: 10.1007/s12250-018-0003-8
Received: 20 June 2017
Accepted: 22 November 2017
Published: 22 March 2018
Porcine deltacoronavirus (PDCoV) is a newly identified virus that causes watery diarrhea in newborn piglets and results in significant economic losses to the pig industry. Since first reported in Hong Kong in 2012, PDCoV has been subsequently detected in USA, South Korea, Thailand, and mainland China. Here we isolated a strain of PDCoV, named CHN-GD-2016, from the intestinal content of a diseased newborn piglet with severe diarrhea in a pig farm in Guangdong, China. PDCoV CHN-GD-2016 could be identified by immunofluorescence with PDCoV specific rabbit antisera, and typical crown-shaped particles with spiky surface projections of this PDCoV were observed with electron microscopy. Genomic analysis showed that the PDCoV CHN-GD-2016 was closely related to other Chinese PDCoV strains, with the highest sequence similarity with the strain CHN/Tianjin/2016. Importantly, inoculation of newborn piglets with 1×105 TCID50 of CHN-GD-2016 by oral feeding successfully reproduced clear clinical symptoms, including vomiting, dehydration, and severe diarrhea in piglets. In addition, the virus RNA in rectal swabs from 1 to 7 days post inoculation was detected, macroscopic and microscopic lesions in small intestine were observed, and viral antigen was also detected in the small intestines with immunohistochemical staining. Collectively, the data show in this study confirms that PDCoV is present in Guangdong, China and is highly pathogenic in newborn piglets.
Differential Effects of Strategies to Improve the Transduction Efficiency of Lentiviral Vector that Conveys an Anti-HIV Protein, Nullbasic, in Human T Cells
2018, 33(2): 142 doi: 10.1007/s12250-018-0004-7
Received: 17 August 2017
Accepted: 13 November 2017
Published: 14 March 2018
Nullbasic is a mutant form of HIV-1 Tat that has strong ability to protect cells from HIV-1 replication by inhibiting three different steps of viral replication: reverse transcription, Rev export of viral mRNA from the nucleus to the cytoplasm and transcription of viral mRNA by RNA polymerase II. We previously showed that Nullbasic inhibits transduction of human cells including T cells by HIV-1-based lentiviral vectors. Here we investigated whether the Nullbasic antagonists huTat2 (a Tat targeting intrabody), HIV-1 Tat or Rev proteins or cellular DDX1 protein could improve transduction by a HIV-1 lentiviral vector conveying Nullbasic-ZsGreen1 to human T cells. We show that overexpression of huTat2, Tat-FLAG and DDX1-HA in virus-like particle (VLP) producer cells significantly improved transduction efficiency of VLPs that convey Nullbasic in Jurkat cells. Specifically, co-expression of Tat-FLAG and DDX1-HA in the VLP producer cell improved transduction efficiency better than if used individually. Transduction efficiencies could be further improved by including a spinoculation step. However, the same optimised protocol and using the same VLPs failed to transduce primary human CD4+ T cells. The results imply that the effects of Nullbasic on VLPs on early HIV-1 replication are robust in human CD4+ T cells. Given this significant block to lentiviral vector transduction by Nullbasic in primary CD4+ T cells, our data indicate that gammaretroviral, but not lentiviral, vectors are suitable for delivering Nullbasic to primary human T cells.
An Attenuated Highly Pathogenic Chinese PRRS Viral Vaccine Confers Cross Protection to Pigs against Challenge with the Emerging PRRSV NADC30-Like Strain
2018, 33(2): 153 doi: 10.1007/s12250-018-0027-0
Received: 10 October 2017
Accepted: 30 January 2018
Published: 29 March 2018
A novel PRRSV strain was isolated in China that was genetically similar to the NADC30 strain which is reported to have spread throughout China. The objective of the present study was to evaluate the cross-protective efficacy of the live vaccine TJM-F92 in young pigs against challenge with a NADC30-like strain, HN201605. Twenty-five PRRSV- and antibody-free pigs were randomly divided into the following five groups: Vac/ChA, Unvac/ChA, Vac/ChB, Unvac/ChB and the mock. The pigs in groups Vac/ChA and Vac/ChB were inoculated intramuscularly with 1 mL TJM-F92 (105.0 TCID50/mL). At 28 days post vaccination (0 days post challenge), groups Vac/ChA and Unvac/ChA were inoculated intranasally with 104.5 TCID50/mL PRRSV strain TJ F3 (2 mL/pig), while groups Vac/ChB and Unvac/ChB were inoculated, using the same route, with the same dose of the NADC30-like strain HN201605 F3. Protective effects of the PRRSV strain were observed in all pigs in the Vac/ChA and Vac/ChB groups. Neither high fever nor signs of clinical disease were observed through the experiment in these groups, whereas pigs in Unvac/ChA group exhibited serious clinical symptoms, pathological lesions, and weight loss. In Unvac/ChB group, pigs developed milder clinical symptoms, which demonstrated that the NADC30- like strain HN201605 had moderate pathogenicity. The results suggest that the MLV vaccine strain TJM-F92 is an effective and safe vaccine candidate for use in China.
Mechanisms and Effects on HBV Replication of the Interaction between HBV Core Protein and Cellular Filamin B
2018, 33(2): 162 doi: 10.1007/s12250-018-0023-4
Received: 30 October 2017
Accepted: 12 January 2018
Published: 28 March 2018
Hepatitis B virus (HBV) infection is one of the major problems that threatens global health. There have been many studies on HBV, but the relationship between HBV and host factors is largely unexplored and more studies are needed to clarify these interactions. Filamin B is an actin-binding protein that acts as a cytoskeleton protein, and it is involved in cell development and several signaling pathways. In this study, we showed that filamin B interacted with HBV core protein, and the interaction promoted HBV replication. The interaction between filamin B and core protein was observed in HEK 293T, Huh7 and HepG2 cell lines by co-immunoprecipitation and co-localization immnofluoresence. Overexpression of filamin B increased the levels of HBV total RNAs and pre-genome RNA (pgRNA), and improved the secretion level of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg). In contrast, filamin B knockdown inhibited HBV replication, decreased the level of HBV total RNAs and pgRNA, and reduced the secretion level of HBsAg and HBeAg. In addition, we found that filamin B and core protein may interact with each other via four blocks of argentine residues at the C-terminus of core protein. In conclusion, we identify filamin B as a novel host factor that can interact with core protein to promote HBV replication in hepatocytes. Our study provides new insights into the relationship between HBV and host factors and may provide new strategies for the treatment of HBV infection.
Monoclonal Antibody-Based Serological Detection Methods for Wheat Dwarf Virus
2018, 33(2): 173 doi: 10.1007/s12250-018-0024-3
Received: 30 October 2017
Accepted: 30 January 2018
Published: 09 April 2018
Wheat dwarf disease caused by wheat dwarf virus (WDV) is currently present in wheat growing regions in China and causes serious losses in wheat yield. To develop reliable and effective serological detection methods for WDV, the coat protein (CP) gene of WDV was cloned and expressed in Escherichia coli. The purified recombinant CP protein was immunized to BALB/c mice, and four hybridoma cell lines (i.e. 18G10, 9G4, 23F4 and 22A10) secreting anti-WDV monoclonal antibodies (MAbs) were obtained through the hybridoma technique. Using the prepared MAbs, an antigencoated-plate enzyme-linked immunosorbent assay (ACP-ELISA) and a dot-ELISA were established for detecting WDV in wheat samples. The most sensitive ACP-ELISA based on MAb 23F4 or 22A10 was able to detect WDV in 1:163,840 (w/v, g/mL) diluted WDV-infected wheat plant crude extracts. The dot-ELISA based on MAb 23F4 was the most sensitive and able to detect the virus in 1:5,120 (w/v, g/mL) diluted wheat plant crude extracts. A total of 128 wheat samples were collected from wheat growing regions in the Shaanxi and Qinghai provinces, China, and were screened for the presence of WDV using two developed serological assays. Results from the survey showed that approximately 62% of the samples were infected with WDV. PCR followed by DNA sequencing and sequence alignment validated the results from the two serological assays. Therefore, we consider that these two serological detection methods can be significantly useful for the control of WDV in China.
A Duplex Real-Time PCR Assay for the Simultaneous Detection of Porcine Circovirus 2 and Circovirus 3
2018, 33(2): 181 doi: 10.1007/s12250-018-0025-2
Received: 20 November 2017
Accepted: 30 January 2018
Published: 03 April 2018
Porcine circoviruses (PCV) include PCV1, PCV2, and the new-emerging PCV3. PCV2 is pathogenic to pigs, but the pathogenicity of PCV3 in pigs is debatable. Recently, there have been frequent reports of PCV2 and PCV3 co-infections in clinical samples. Thus, it would be practical to develop a duplex PCR method to detect PCV2 and PCV3 simultaneously. In this study, specific primers and probes were designed to target PCV2 cap and PCV3 rep genes. A duplex real-time PCR method was then developed to detect the two viruses. The assay was found to be highly specific, sensitive, and reproducible for PCV2/3 without cross-reactions with other swine pathogens. The sensitivity of this assay was 2.9 copies for the PCV2 plasmid and 22.5 copies for the PCV3 plasmid. The established assay was then used to detect PCV2/3 infection in 340 clinical samples collected in the first half of 2017. The results showed that the co-infection rate of PCV2/3 in the samples was 27.6%. Our study provides an important tool that can be used to perform urgently needed surveys for the two porcine circoviruses to evaluate their impact on the swine industry.
HearNPV Pseudotyped with PIF1, 2, and 3 from MabrNPV: Infectivity and Complex Stability
2018, 33(2): 187 doi: 10.1007/s12250-018-0014-5
Received: 15 December 2017
Accepted: 08 January 2018
Published: 16 April 2018
Effective oral infection is set off by interaction of a group of conserved per os infectivity factors (PIFs) with larval midgut columnar epithelial cells. We constructed pseudotyped viruses by substituting pif1, pif2 or pif3 genes of Helicoverpa armigera nucleopolyhedrovirus (HearNPV) with their homologs from Mamestra bracissae multiple nucleopolyhedrovirus and tested their infectivity to tissue culture cells and to larvae. Transfection and infection assays revealed that all recombinant viruses generated infectious budded virus in both cell culture and in larvae. Electron microscopy showed synthesized occlusion body and occlusion derived virus (ODV) were morphologically indistinguishable from those of the parental virus. By contrast, feeding assays revealed that pseudotyped viruses could not rescue oral infectivity except for pif3 pseudotyped virus that only partially rescued oral infectivity but at a mortality rate much lower than that of the parental HearNPV. Consistent with the bioassay result, PIF complex was detected in ODVs of pif3 pseudotyped virus only but not in pif1 or pif2 pseudotyped viruses. Our results suggest that PIF complex is essential for oral infectivity, and in the formation of the PIF complex, PIF1, 2 are virus-specific while PIF3 does not appear to be as specific and can function in heterologous environment, albeit to a much more limited extent.
First Serological Evidence on Endemicity of HEV Infection in Wild Boar (Sus scrofa) Populations from Portugal
2018, 33(2): 197 doi: 10.1007/s12250-018-0008-3
Received: 12 June 2017
Accepted: 08 January 2018
Published: 22 April 2018
Hunting is a common and popular pastime in Portugal. Hunted animals are, generally, for human consumption as meat or local products that are consumed without cooking, increasing the risk of zoonotic transmission of several infectious agents. The present study intended to characterize HEV infection in hunted wild boars (species Sus scrofa) from two regions of Portugal in order to estimate its importance as reservoir for zoonotic spread of HEV to humans, and its possible implication in public health. Markers for both past and/or ongoing HEV infection were evaluated in serum, bile and stool samples of 29 wild boars. The presence of specific HEV antibodies as marker of past infection was evaluated in serum samples, while active HEV infection was evaluated through the detection of HEV genome in bile and stool samples. HEV specific antibodies were detected in 14% of the studied animals, while none of the tested bile or stool samples revealed detectable HEV genome. Despite no active HEV infection was demonstrated in the hunted animals included in the present study, serological analysis revealed the endemicity of HEV infection in Portuguese wild boars from the studied regions, corroborating its possible role as zoonotic reservoir of such virus. The proved endemicity of HEV infection among wild boars further support the importance of including HEV in national and regional surveillance programs for wild animal diseases, as well as to the awareness for thorough cook all wild boar products and to the education of occupationally exposed people in order to prevent HEV infection.
NAP1L1 Regulates Hepatitis C Virus Entry and Interacts with NS3
2018, 33(2): 205 doi: 10.1007/s12250-018-0006-5
Received: 13 October 2017
Accepted: 28 November 2017
Published: 14 April 2018
NAP1L1 has been shown to function in the life cycle of several DNA virus and retrovirus. However, whether NAP1L1 regulates hepatitis C virus (HCV), a positive-stranded RNA virus, remain to be elucidated. In this study, we identified NAP1L1 as a novel binding partner for HCV NS3. Our results suggest that NAP1L1 contributes to HCV entry, but not viral replication. These findings provide mechanistic insight into the role of NAP1L1 in HCV life cycle and extend the role of NAP1L1 to RNA virus.
Characteristics of HIV-1 Molecular Epidemiology in Suzhou, China, from 2009 to 2014
2018, 33(2): 209 doi: 10.1007/s12250-018-0022-5
Received: 11 October 2017
Accepted: 12 January 2018
Published: 16 April 2018
Suzhou is experiencing a dynamic human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) epidemic. While serology based surveillance systems have reported the spread of HIV/AIDS, detailed tracking of its molecular epidemiology and transmission in populations remains mostly undetermined. Here, we conducted a molecular epidemiology study involving 261 HIV-1-positive serum samples collected in Suzhou from 2009 to 2014 and systematically analyzed the dynamic characteristics of virus genetic variation. Sequencing data showed that the predominant HIV-1 subtype was CRF01_AE (52.1%), followed by CRF07_BC (30.3%), CRF08_BC (8.4%), and B (8.0%). The genotype distance of the B-subtype strain was great and its degree of variation was high. Interestingly, a cluster of eight members was found in the phylogenetic tree of CRF01_AE samples from men who have sex with men (MSM). Although the main transmission route of HIV-1 circulating in Suzhou appeared to be sexual transmission, maternal vertical transmission was also observed in this study. These data provide the basis for a rational and effective prevention and control strategy to prevent further spread of HIV-1 in Suzhou.
Evaluation of Antibody-Dependent Enhancement of SARS-CoV Infection in Rhesus Macaques Immunized with an Inactivated SARS-CoV Vaccine
2018, 33(2): 201 doi: 10.1007/s12250-018-0009-2
Received: 20 August 2017
Accepted: 08 January 2018
Published: 14 April 2018
Currently, effective antiviral strategies to control SARS-CoV infections are lacking; vaccination is still regarded as the major approach for preventing SARS and related diseases. Generally, virus-specific antibodies play important roles in the control of viral infections. However, the presence of specific antibodies can be beneficial for infection in case of some viruses including flaviviruses, CoVs, and retroviruses (de Alwis et al. 2014 ; Jolly and Weiss 2000 ; Takano et al. 2008 ). Vaccine-induced enhancement of susceptibility to SARS-CoV has been documented. One study showed that the antibody against SARS-CoV spikes protein potentiated infection of both monocytic and lymphoid cell lines, which do not express the virus receptor, and reported antibody-dependent enhancement (ADE)-mediated vaccine-induced infection aggravation (Yip et al. 2014 ). We previously reported that an inactivated SARS-CoV Z-1 vaccine effectively elicits a neutralizing and protective antibody response in rhesus macaques (Luo et al. 2007 ; Zhou et al. 2005 ). Thus, to ensure the safety of the vaccine in clinical use, the present study examined whether the vaccine can trigger ADE.
