From phyllosphere to insect cuticles: silkworms gather antifungal bacteria from mulberry leaves to battle fungal parasite attacks

BACKGROUND

Bacterial transfers from plants to insect herbivore guts have been well investigated. However, bacterial exchanges between plant phyllospheres and insect cuticles remain unclear, as does their related biological function.

RESULTS

Here, we report that the cuticular bacterial loads of silkworm larvae quickly increased after molting and feeding on the white mulberry (Morus alba) leaves. The isolation and examination of silkworm cuticular bacteria identified one bacterium Mammaliicoccus sciuri that could completely inhibit the spore germination of fungal entomopathogens Metarhizium robertsii and Beauveria bassiana. Interestingly, Ma. sciuri was evident originally from mulberry leaves, which could produce a secreted chitinolytic lysozyme (termed Msp1) to damage fungal cell walls. In consistency, the deletion of Msp1 substantially impaired bacterial antifungal activity. Pretreating silkworm larvae with Ma. sciuri cells followed by fungal topical infections revealed that this bacterium could help defend silkworms against fungal infections. Unsurprisingly, the protective efficacy of ΔMsp1 was considerably reduced when compared with that of wild-type bacterium. Administration of bacterium-treated diets had no negative effect on silkworm development; instead, bacterial supplementation could protect the artificial diet from Aspergillus contamination.

CONCLUSIONS

The results of this study evidence that the cross-kingdom transfer of bacteria from plant phyllospheres to insect herbivore cuticles can help protect insects against fungal parasite attacks. Video Abstract.

Immunogenicity and protective efficacy of human metapneumovirus virus-like particles produced by a recombinant baculovirus in mice

BACKGROUND

Human metapneumovirus (HMPV) causes respiratory tract infections among infant, elderly, and immunocompromised patients, with significant mortality. Currently no licensed vaccines or therapeutic agents of HMPV exist.

METHODS

HMPV virus-like particle (VLP) was constructed by co-expressing fusion protein of HMPV and matrix 1 protein of influenza virus using the baculovirus expression. Mice were immunized with VLP with or without aluminum hydroxide (alum) adjuvant by intramuscular route respectively. Sera were determined for titers of IgG and neutralizing antibody. Splenic lymphocytes were determined by IFN-γ and IL-4 ELISPOT. Mice were challenged with HMPV, and protective efficacy was evaluated.

RESULTS

We generated HMPV VLP in baculovirus expression system. After three times immunization, IgG antibody titers induced by VLP formulated with or without alum adjuvant group were 273,066 ± 100,331 and 136,533 ± 47,269 respectively, there was no difference (p ˃ 0.05); the neutralizing antibody titers vaccinated with VLP plus with alum adjuvant (266 ± 92) were higher than those of the VLP alone group (106 ± 37). For IFN-γ, mice vaccinated with VLP with or without alum adjuvant are 151 ± 36.4 and 77.0 ± 17.1SFC/106 respectively, there was difference (p = 0.03); For IL-4, they are 261.3 ± 38.7 versus 125.67 ± 29.78SFC/106 respectively, the difference was significant (p = 0.009). After challenge, in pathological analysis, the overall lesion scores in the VLP plus with and without alum adjuvant were 3.25 and 5.6 respectively, those of control group is 8. For immunohistochemical analyses, the average optical density of the lungs in the VLP immunized group containing adjuvant (9.07 ± 1.74) was lower than that in the VLP group without adjuvant (12.83 ± 2.31, p = 0.14).

CONCLUSIONS

This is the first study to demonstrate that HMPV VLP was successfully prepared in the baculovirus expression system. HMPV VLP could induce specific humoral and cellular immune responses as well as protective efficacy, and aluminum hydroxide may be an effective adjuvant in mice.

Development and biological activity of long-acting recombinant human interferon-α2b

BACKGROUND

The type I human interferon (IFN) family consists of a group of cytokines with a multiplicity of biological activities, including antiviral, antitumor, and immunomodulatory effects. However, because the half-life of IFN is short, its clinical application is limited. Increasing the yield and biological activity of IFN while extending its half-life is currently the focus of IFN research.

RESULTS

Two novel long-acting recombinant human IFN-α2b (rhIFN-α2b) proteins were designed in which the carboxyl-terminal peptide (CTP) of the human chorionic gonadotropin β su bunit and N-linked glycosylation sequences were linked to rhIFN-α2b. They were designated IFN-1CTPON (fused at the C-terminus of rhIFN-α2b) and IFN-2CTPON (fused at both the C-terminus and N-terminus of rhIFN-α2b). Monoclonal CHO cell strains stably and efficiently expressing the IFNs were successfully selected with methotrexate (MTX), and the highest expression levels were 1468 mg/l and 1196 mg/l for IFN-1CTPON and IFN-2CTPON, respectively. The proteins were purified with affinity chromatography and molecular sieve chromatography. IFN-1CTPON and IFN-2CTPON showed antiviral and antiproliferative activities in vitro. Notably, the half-life of IFN-1CTPON and IFN-2CTPON in vivo were three-fold and two-fold longer than that of commercially available rhIFN-α2b.

CONCLUSIONS

CHO cell strains stably expressing long-acting rhIFN-α2b were screened. The purified IFN-CTPON protein has biological activity and an extended half-life, and therefore potential applications.

Epidemiology of human adenovirus infection in children hospitalized with lower respiratory tract infections in Hunan, China

To investigate the current genotypes of circulating human adenovirus (HAdV) strains, we molecularly genotyped HAdV in the nasopharyngeal aspirates (NPAs) of patients with acute lower respiratory tract infections (ALRTIs) and attempted to determine their associations with clinical symptoms. A total of 4751 NPA samples were collected from 4751 patients admitted to Hunan Provincial People's Hospital from September 2007 to March 2014, of which 447 (9.4%) samples were HAdV positive. Fourteen different HAdV types were identified; HAdV types 1 to 7 (HAdV 1‐7) were identified in 95.7% of the 447 NPA samples with HAdV‐7 and HAdV‐3 being the most prevalent. In addition, 93.3% (417 of 447) of patients were younger than 5 years. The incidence of HAdV infection peaked in summer. Different HAdV types showed a predilection for different age groups and different seasonal distribution patterns. Coinfection of HAdVs and other respiratory viruses was detected in 63.3% (283 of 447) of the HAdV‐positive samples. The most common clinical diagnosis was pneumonia and the most common symptoms were fever and cough. In comparison with children infected with HAdV‐3 alone, those infected with HAdV‐7 alone had an increased frequency of severe pneumonia involvement (11.6% vs 32.4%; P = 0.031), higher intensive care unit admission rates (7.0% vs 26.5%; P = 0.019), and a longer length of hospital stay (P = 0.03). Mixed infections in younger children were associated with a longer hospital stay (P = 0.023). Our results demonstrate the recent changes in the trends of circulating HAdV genotypes associated with ALRTIs in Hunan China.

A novel hepatovirus identified in wild woodchuck Marmota himalayana

Hepatitis A virus (HAV) is a hepatotropic picornavirus that causes acute liver disease worldwide. Here, we report on the identification of a novel hepatovirus tentatively named Marmota Himalayana hepatovirus (MHHAV) in wild woodchucks (Marmota Himalayana) in China. The genomic and molecular characterization of MHHAV indicated that it is most closely related genetically to HAV. MHHAV has wide tissue distribution but shows tropism for the liver. The virus is morphologically and structurally similar to HAV. The pattern of its codon usage bias is also consistent with that of HAV. Phylogenetic analysis indicated that MHHAV groups with known HAVs but forms an independent branch, and represents a new species in the genus Hepatovirus within the family Picornaviridae. Antigenic site analysis suggested MHHAV has a new antigenic property to other HAVs. Further evolutionary analysis of MHHAV and primate HAVs led to a most recent common ancestor estimate of 1,000 years ago, while the common ancestor of all HAV-related viruses including phopivirus can be traced back to 1800 years ago. The discovery of MHHAV may provide new insights into the origin and evolution of HAV and a model system with which to explore the pathogenesis of HAV infection.

Prevalence of adenovirus in children with acute respiratory tract infection in Lanzhou, China

Background

Human adenovirus (HAdV) is an important agent causing respiratory tract infection in children. Information on the epidemiological and clinical features of HAdV is limited in children with acute respiratory tract infections (ARTIs) in China, especially those of a novel genotype, Ad55.

Methods

In total, 1169 nasopharyngeal aspirates were collected from children younger than 14 years with ARTIs between November 2006 and November 2009. The polymerase chain reaction (PCR) was used to screen HAdVs. All PCR-positive products were sequenced.

Results

74 of 1169 (6.33%) specimens were positive for HAdVs. Among positive cases, AdV3 (58/74) was detected most frequently, followed by AdV11 (10/74), AdV2 (2/74), AdV7 (2/69), AdV6 (1/74), and AdV1 (1/74). AdV55 was found in one case. The incidence of HAdV infection peaked in children aged 3–7 years. The most common clinical diagnosis was upper respiratory infection, and the most common syndrome was fever and cough.The comparison of HAdV and RSV group revealed that Children infected with group AdV were significant older than children infected with group RSV, had more fever but less frequently wheezing, and cough, crackles, and cyanosis, The duration of hospitalization between the AdV group and RSV group was not significant, but a greater frequency of LRTIs was observed in RSV group.

Conclusions

HAdV is an important viral agent in children with ARTIs in Lanzhou City, China. Multiple HAdV serotypes co-circulated with Ad3, which was predominant in this 3-year study. The novel AdV55 genotype was found in one case. No fixed seasonal rhythm could be identified.

[The research of saffold virus in children with lower respiratory tract infection in Changsha]

OBJECTIVE

To investigate prevalence of Saffold virus (SAFV) in Changsha area of hospitalized children with respiratory tract infection, and to discuss whether this virus is related to respiratory tract infection of children.

METHODS

643 nasopharyngeal aspirates samples were collected from hospitalized children with respiratory tract infection of the first affiliated hospital of Hunan nomal university during Nov. 2007 to Oct. 2008. Real-time fluorescent quanti-tative PCR(FQ-PCR) performed to screen the 5'UTR gene. And then analyze clinical data.

RESULTS

SAFV were detected in 67 patients (10.42%) out of the 643 children, it was not detected over 5 years of age. The virus were detected in 8 patients (25.81%) out of the 31 children with persistent pneumonia and chronic pneumonia, there was statistically significant.

CONCLUSION

There existed SAFV infection in hospitalized children with lower respiratory infection in Changsha area; SAFV maybe related to disease onset with lower respiratory tract infection of children.

[Molecular epideiological and clinical feature of human metapneumovirus in children with acute respiratory tract infection in Nanjing City]

OBJECTIVE

To investigate the molecular epideiological and clinical feature of human metapneumovirus in children with acute respiratory tract infection in Nanjing city, China.

METHOD

Nasopharyngeal aspirates and nasopharyngeal swab were taken from 642 outpatients or hospitalized pediatric patients with acute at the Children Hospital of Nanjing, Jiangsu Province, China, between August 2009 and July 2010. Respiratory speciments were tested for the M gene of hMPV by reverse-transcription polymerase chain reaction (RT-PCR). All RT-PCR positive products were sequenced and phlogenetic analysis was conducted.

RESULT

hMPV was detected in 35 (5.5%) of the 642 children. Phylogenetic analysis revealed that 51.4% of the hMPV were B1, 31.4% were A2b. The peak of the positive rate was in April. The majority of the hMPV-positive patients(71.4%) were 0-1 years old. Of the 35 hMPV-positive patients, 15 (42.8%) were co-infected with other respiratory viruses, and human rhinovirus (HRV) were the most common additional respiratory virus. The most common clinical diagnosis was pneumonia (48.6%).

CONCLUSION

Human metapneumovirus is an important pathogen of acute respiratory tract infection in children in Nanjing city. The subtype B1 was the predominating lineage in 2009-2010 in Nanjing city. No significant differences were found for clinical characteristics between genotype A and genotype B human metapneumovirus infection in children in Nanjing.

[Detection and clinical characteristics analysis of human bocavirus 1-3 in children for acute respiratory infection in Lanzhou area]

OBJECTIVE

To study the clinical and molecular epidemiology characteristics of human Bocavirus 1-3 (HBoV1-3) in children for acute respiratory infection in Lanzhou area.

METHODS

Nasopharyngeal aspiration samples and throat swabs were collected from 524 children with ARTI at the First Hospital of Lanzhou University, Gansu Province, China, between December 2009 and November 2010. Nested PCR was employed to screening HBoV1-3, which amplified a 518-bp fragment of the partial NS1 gene. Furthermore, a standard reverse transcription-PCR was used to screen for other common respiratory viruses.

RESULTS

The overall frequency of HBoV was 8.2% (43/524), lining up behind human rhinovirus, RSV, parainfluenza virus 3. Thirty of the HBoV-postive children(69.8%) were co-infected with other respiratory viruses. The prevalence of HBoV1 in ALRTI was obviously higher than that in AURI. The 2 HBoV2 NS1 sequences shared 99% and 100% nucleotide sequence identity with HBoV2 strain CU47TH respectively. Two cases of HBoV2 postive children appears gastrointestinal symptoms. The one HBoV3 NS1 sequences shared 99% nucleotide sequence identity with HBoV3 isolate 46-BJ07.

CONCLUSION

The HBoV3 was detected at the first time in lanzhou area. HBoV1-3 infection exists in children with acute respiratory tract infections in Lanzhou region, HBoV1 were dominant. The mixed infection rate was higher.

[Detection and clinical study on coronavirus HKU1 with acute lower respiratory tract infections of hospitalized children in Changsha]

OBJECTIVE

In order to understand the epidemiological and virologic characteristics of coronavirus HKU1 infection in hospitalized children with acute respiratory tract infection (ARTI) in Changsha.

METHODS

1165 nasopharyngeal aspirates (NPA) specimens were collected from hospitalized children with ARTI between September 2007 and August 2008 in Changsha. Specimens were screened for pol gene of coronavirus HKU1 by polymerase chain reaction. All positive amplification products were confirmed by sequencing and compared with those in GenBank.

RESULTS

Coronavirus HKU1 were detected in 12 patients (1.03%) out of the 1165 children. The patients were from 8 days to 3 years. The most common clinical diagnosis was bronchopneumonia(83.33%). Similarity of coronavirus HKU1 with those published in the GenBank at nucleotide levels was 98.18% - 100%.

CONCLUSION

Coronavirus HKU1 may be important pathogens in children with acute lower respiratory tract infection. Coronavirus HKU1 infections are common in children under 3 years old. There is no significant difference in the infectious rate between the boys and the girls. The peak of its prevalence is in spring and winter. A single genetic lineage of Coronavirus HKU1 was revealed in human subjects in Changsha.

[Molecular epidemiological and clinical features of coronavirus HKU1 in children with acute respiratory tract infection in Lanzhou]

OBJECTIVE

Human coronavirus (CoV)-HKU1 (HCoV-HKU1) was first isolated by Woo et al in Hong Kong. Several successive reports confirmed retrospectively that this new human coronavirus was circulating in different countries worldwide. However, the impact and the role of the emerging HCoV-HKU1 were not defined in children with ARTI. The objective of this study was to investigate the molecular epidemiology and clinical characteristics of HCoV-HKU1 infection in children with ARTI in Lanzhou, China.

METHOD

Nasopharyngeal aspiration (NPA) samples were collected from 301 children with ARTI at the First Hospital of Lanzhou University, Gansu Province, China, between November 2007 and October 2008. Demographic data and clinical findings of these children were collected at the same time. The informed consent was obtained from their parents. This study protocol was approved by the hospital ethics committee. The reverse transcription polymerase chain reaction (RT-PCR) was employed to screen HCoV-HKU1. Furthermore, other common respiratory viruses were screened in HCoV-HKU1 positive samples. All PCR positive products were sequenced, and phylogenetic analysis was conducted.

RESULT

The overall frequency of HCoV-HKU1 infection was 5.0% (15/301). The HCoV-HKU1 pol gene sequences shared a 95.8% - 99.6% nucleotide identity with the human coronavirus-HKU1 strain, whereas the amino acid identity was 90.7% - 99.3%. The phylogenetic analysis revealed that the HCoV-HKU1 strain pol gene clustered with the HCoV-HKU1 strain N15 genotype B (no. DQ415911); 11 of 15 HCoV-HKU1 positive sample tested were mixed-infection. HCoV-HKU1 was detected only from November to April. Positive specimens peaked in November. Children with HCoV-HKU1 infection varied in age from 15 day to 12-years (median age, 10 months). The clinical diagnoses of HCoV-HKU1 positive patients included those with AURI and LURI. The clinical presentations of HCoV-HKU1 positive children included fever, cough, sputum production, diarrhea, vomiting; pharynx engorgement, crackles, and wheezing. The mean hospital stay of the 14 patients was 9.9 days. Six of 15 HCoV-HKU1 positive patients had an underlying illness, and they were all inpatients (hospital stay, mean, 11.2 days). There was no statistically significant difference in the detection rate between the two groups with and without underlying illnesses.

CONCLUSION

Human CoV-HKU1 infection exists in children with respiratory tract infections in Lanzhou region. A single HCoV-HKU1 genotype B was circulating locally. The symptoms and clinical diagnoses of those infected with HCoV-HKU1 had no specificity as compared with patients with other common respiratory viruses infection.

Novel human bocavirus in children with acute respiratory tract infection

Human bocavirus (HBoV) and HBoV2, two human bocavirus species, were found in 18 and 10 of 235 nasopharyngeal aspirates, respectively, from children hospitalized with acute respiratory tract infection. Our results suggest that, like HBoV, HBoV2 is distributed worldwide and may be associated with respiratory and enteric diseases.

Human bocavirus infection in young children with acute respiratory tract infection in Lanzhou, China

Human bocavirus (HBoV) is a recognized human parvovirus associated with acute respiratory tract infection. However, HBoV has yet to be established as a causative agent of respiratory disease. In this study, the epidemiological and virological characteristics of HBoV infection were studied in children with acute respiratory tract infection in China. In total, 406 children younger than 14 years of age with acute respiratory tract infection were included in this prospective 1-year study. HBoV was detected in 29 (7.1%) of the 406 children. No clear seasonal fluctuation was observed in infection rates of HBoV. Of the 29 children infected with HBoV, 16 (55.2%) were coinfected with other respiratory viruses, most commonly respiratory syncytial virus (RSV). Viral coinfection with HBoV did not affect the severity of the respiratory disease (P = 0.291). The number of HBoV genome copies ranged from 5.80 x 10(2) to 9.72 x 10(8) copies/ml in nasopharyngeal aspirates among HBoV-positive specimens by real-time PCR, and neither coinfection nor the severity of disease correlated with the viral load (P = 0.148, P = 0.354, respectively). The most common clinical features were cough and acute upper respiratory infection, and acute bronchopneumonia. Additionally, the NP-1 gene of HBoV showed minimal sequence variation. These data suggest that HBoV is frequent in young children with acute respiratory tract infection in Lanzhou, China, and RSV is the most common coinfecting virus. There was no apparent association between the viral load of HBoV and coinfection or disease severity. The NP-1 gene was highly conserved in HBoV.

[Analysis of human metapneumovirus genotype in Hunan, China and its attachment protein G sequence character]

OBJECTIVE

To understand the genotypes of human metapneumovirus (hMPV) and the genetic character of hMPV attachment protein G sequence in Hunan, China.

METHODS

232 nasopharyngeal aspirates (NPA) samples from hospitalized children with acute respiratory infections were collected from Hunan, China in 2005. HMPV was detected. The full length of G glycoprotein genes were amplified and sequenced. Bioinformatics soft-wares were employed to analyze the sequences.

RESULTS

17/232 (7.3%) were showed hMPV positive. And co-infection rate with other viruses is 35%. The diagnoses of these hMPV positive cases are pneumonia, bronchiolitis and bronchopneumonia. Phylogenetic analysis for G genes from 13 hMPVs revealed the existence of four major subgroups: A1, A2, B1, B2 in Hunan, China in 2005. There are four types of sequence lengths of hMPV G glycoprotein, which are 711, 675, 660, 696nt. It is different in potential N-linked glycosylation sites and number of cysteine residues among these hMPVs of Hunan, China and Beijing, China. Also it is different from those in Japan and North America.

CONCLUSION

The investigation of hMPV from Hunan, China in 2005 revealed the high speed of genetic variation and the marked character of geographic epidemic differences.

[WU polyomavirus and KI polyomavirus detected in specimens from children with acute respiratory tract infection in China]

OBJECTIVE

To investigate newly identified polyomavirus WUV and WUV and KIPyV are associated with acute respiratory infections in China, tests were developed to detect WUV and KIPyV gene fragments from nasopharyngeal aspirates collected from children with ARI fron Nov. 2006 to Oct. 2007.

METHODS

A total of 318 clinical samples were tested for WUV and KIPyV using PCR method. The positive products were sequenced and compared with those in GenBank.

RESULTS

14 of the 318 Samples were positive (WUV was 2.2%, KIPyV was 2.2%). All of children who were positive for WUV or KIPyV had respiratory illness.

CONCLUSION

Polyomavirus WU and KIPyV infection may be associated with upper and lower respiratory diseases.

[Cloning, expression and purification of interferon-kappa, a novel human interferon, and its antiviral activity]

OBJECTIVE

To prepare human interferon-k (hIFN-kappa) and study its biological activities.

METHODS

Whole length of hIFN-kappa's cDNA was cloned, and its sequence was chemically synthesized according to the optimized codons of E.coli, then was expressed in E.coli DH5alpha. After purified, the rhIFN-kappa protein was tested for its various kinds of biological activities.

RESULTS

The purity of rhIFN-kappa was above 90%. In WHIS-VSV system, the antiviral activity of rhIFN-kappa was 2.0 x 10(6) IU/mg. Compared with rhIFN-alpha-2b, the biological activities of rhIFN-kappa were all feeble, including antiviral activity, promoting NK cell activity and anti-proliferation activity.

CONCLUSION

Antiviral activities of rhIFN-kappa on cell lines of different species are different, different viruses show different sensitivity to rhIFN-kappa.

[Biological activities of recombinant human interferon Epsilon]

OBJECTIVE

To construct a novel recombinant rhIFN-epsilon155ser, and study its biological activities.

METHODS

The whole sequence of rhIFN-epsilon was artificially synthesized and some codons were altered according to the preferred codon using of E.coli. The sequence was cloned into plasmid vector pBV220 to express in E.coli DH5alpha. After purification and re-folding of rhIFN-epsilon155ser inclusion body, the final product was tested for its biological activities, including anti-viral, anti-proliferative and NK cell enhancing activities. At the same time, by using DNA microarray biochips, the gene expression patterns in the rhIFN-epsilon155ser and rhIFN-alpha2b treated cells were compared and analyzed.

RESULTS

The re-built rhIFN-epsilon155ser sequence was expressed in E.coli as a form of inclusion body. After purified and re-folded, the rhIFN-epsilon155ser protein reached a purity of above 95%. The rhIFN-epsilon155ser protein had a specific anti-viral activity of about 6 x 10(5) IU/mg in WISH/VSV system. Its anti-proliferative activity and NK cell enhancing activities in vitro seemed to be lower than that of rhIFN-alpha2b. Data obtained from microarray biochips indicated that there were 283 pieces increasing 2 folds and 1489 pieces decreasing 2 folds among totally 22,278 pieces of human genes were found in the rhIFN-epsilon155ser treated cells; more changes in gene expression pattern were detected in the rhIFN-alpha treated cells.

CONCLUSION

A novel recombinant rhIFN-epsilon155ser was constructed, which belonged to type 1 interferon. The biological activities of rhIFN-epsilon155ser were compared with rhIFN-alpha2b. The changes of gene expression pattern in the interferon treated cells were detected, analyzed and discussed.