Rapid and Simultaneous Detection of Five, Viable, Foodborne Pathogenic Bacteria by Photoinduced PMAxx-Coupled Multiplex PCR in Fresh Juice.

Escherichia coli, Staphylococcus aureus, Shigella, Pseudomonas aeruginosa, and Klebsiella pneumoniae are common foodborne pathogens. In this study, the light-induced PMAxx-coupled multiplex PCR (PMAxx-mPCR) was established to detect the aforementioned five foodborne pathogens in fresh juice at the same time. Moreover, PMAxx pretreatment could effectively distinguish live bacteria from dead bacteria. The optimized PMAxx pretreatment conditions were incubation with a final concentration of 10 µmol/L PMAxx for 10 min and then photolysis for 8 min. After PMAxx pretreatment, the difference in Ct values with or without PMAxx was determined by quantitative real-time PCR. The results showed a significant difference in Ct value before and after PMAxx treatment. Finally, the bacteria-contaminated fresh juice samples treated with PMAxx dye were detected by mPCR. The detection limit of PMAxx-mPCR was 102 colony-forming units (CFU)/mL for E. coli, Shigella, P. aeruginosa, and K. pneumoniae and 103 CFU/mL for S. aureus. Compared with mPCR detection of samples without PMAxx treatment, the proposed method solved the false-positive problem due to dead bacteria. Hence, an accurate and efficient method for the simultaneous detection of five types of pathogenic bacteria was established. This method could be applied to analytical procedures for ensuring food safety.

Genetic variants in IFIH1 and DDX58 influence hepatitis C virus clearance in Chinese Han population.

AIMS: To investigate the association between two RIG-I-like receptor gene polymorphisms and hepatitis C virus (HCV) infection in Chinese Han population. METHODS: The current study genotyped two selected SNPs (IFIH1 rs3747517 and DDX58 rs9695310) using TaqMan allelic discrimination assay to assess their association with the susceptibility and clinical outcome of HCV infection among 3065 participants (1545 non-HCV infection individuals, 568 spontaneous HCV clearance cases, and 952 persistent infection patients). RESULTS: IFIH1 rs3747517 (dominant model: Adjusted odds ratio [OR] = 1.34, 95% confidence interval [CI] = 1.07-1.68; P = 0.009) and DDX58 rs9695310 (dominant model: Adjusted OR = 1.43, 95% CI = 1.15-1.78; P = 0.001) were associated with chronic hepatitis C (CHC). And the risk of CHC increased when people were carrying more unfavorable rs3747517-GA/AA and rs9695310-GC/CC genotypes from zero to two with the chronic rates of 56.72%, 59.38%, and 69.01%, respectively (Ptrend < 0.001). CONCLUSION: Genetic variations at IFIH1 rs3747517 and DDX58 rs9695310 were independent predictors of chronic hepatitis C in Chinese Han population.

Loop-Mediated Isothermal Amplification Assay for Rapid Detection of Hypothetical Protein Gene in Escherichia Coli Clinical Isolates.

BACKGROUND: Escherichia coli is the most common pathogenic bacteria that frequently causes life-threatening opportunistic human infections, diarrhea, and septicemia in immunocompromised hosts. METHODS: This study aimed to establish a loop-mediated isothermal amplification (LAMP) method for the rapid and sensitive detection of a hypothetical protein from an E. coli-specific gene (GenBank ID: 13702648). The gene was obtained through local and online BLAST, and specific primers were designed for this gene. Reaction conditions were optimized at 65ºC for 30 minutes and 80ºC for 2 minutes, whereas the reaction system contained 5.2 mM Mg2+, 8 U of Bst 2.0 DNA polymerase, 1.4 mM deoxyribonucleotide, and 0.2 and 1.6 µM of the outer and inner primers, respectively. The LAMP method was evaluated using 240 strains of E. coli and 150 strains of non-E. coli. RESULTS: Positive reactions were observed on all 240 strains of E. coli while all non-E. coli strains were negative. Plasmids with the specific gene and mice blood with E. coli were used for sensitivity analysis. The detection limit of LAMP was 100 bacterium/reaction. CONCLUSIONS: Results showed that the LAMP targeted to the hypothetical protein (GenBank ID: 13702648) is a fast, specific, sensitive, inexpensive, and suitable method for the detection of E. coli.

Translocation of microbes and changes of immunocytes in the gut of rapid- and slow-progressor Chinese rhesus macaques infected with SIVmac239.

Human/simian immunodeficiency virus (HIV/SIV) infection can cause severe depletion of CD4(+) T cells in both plasma and mucosa; it also results in damage to the gut mucosa barrier, which makes the condition more conducive to microbial translocation. In this study, we used SIV-infected Chinese rhesus macaques to quantify the extent of microbial translocation and the function of immune cells in the entire gastrointestinal tract and to compare their differences between rapid and slow progressors. The results showed that in the slow progressors, microbial products translocated considerably and deeply into the lamina propria of the gut; the tissue macrophages had no significant differences compared with the rapid progressors, but there was a slightly higher percentage of mucosal CD8(+) T cells and a large amount of extracellular microbial products in the lamina propria of the intestinal mucosa of the slow progressors. The data suggested that although microbial translocation increased markedly, the mucosal macrophages and CD8(+) T cells were insufficient to clear the infiltrated microbes in the slow progressors. Also, therapies aimed at suppressing the translocation of microbial products in the mucosa could help to delay the progression of SIV disease.

[Application of next-generation semiconductor sequencing technologies in genetic diagnosis of inherited cardiomyopathies].

Inherited cardiomyopathy is the most common hereditary cardiac disease. It also causes a significant proportion of sudden cardiac deaths in young adults and athletes. So far, approximately one hundred genes have been reported to be involved in cardiomyopathies through different mechanisms. Therefore, the identification of the genetic basis and disease mechanisms of cardiomyopathies are important for establishing a clinical diagnosis and genetic testing. Next-generation semiconductor sequencing (NGSS) technology platform is a high-throughput sequencer capable of analyzing clinically derived genomes with high productivity, sensitivity and specificity. It was launched in 2010 by Life Technologies of USA, and it is based on a high density semiconductor chip, which was covered with tens of thousands of wells. NGSS has been successfully used in candidate gene mutation screening to identify hereditary disease. In this review, we summarize these genetic variations, challenge and application of NGSS in inherited cardiomyopathy, and its value in disease diagnosis, prevention and treatment.

[The function and application of the IL28B gene in HCV infection and treatment].

Hepatitis C virus (HCV) is the etiological factor for Hepatitis C, which is one of the most important pathogenic factors of chronic liver diseases, cirrhosis and even hepatocellular carcinoma. HCV infection brings great threat to human health. Host genetic background could impact HCV infection, viral clearance, and treatment. Recently, some genome-wide association studies (GWAS) of HCV patients were performed. The results showed that single nucleotide polymorphisms (SNPs) of the IL28B gene, which encodes protein IFN-lambda3, are associated with viral clearance and treatment effectiveness of HCV patients who were cured by PEG-IFNalpha combined with ribavirin (RBV). IFN-lambda3 interacts with its acceptor, a heterodimer (IFN-lambdaR1 x IL-10R2), and upregulates the IFN-stimulated gene factors (ISGF). IFN-lambda3 plays roles in antiviral, antitumor, and immunoloregulation, and thus it might become a potential drug for Hepatitis C treatment. However, the mechanism of the IL28B gene in HCV infection and treatment is unclear, and further studies are needed to reveal the veils and provide theoretical basis for developing a new antiviral drug in clinic.

Coinfection with influenza virus and non-typeable Haemophilus influenzae aggregates inflammatory lung injury and alters gut microbiota in COPD mice.

Background: Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is associated with high mortality rates. Viral and bacterial coinfection is the primary cause of AECOPD. How coinfection with these microbes influences host inflammatory response and the gut microbiota composition is not entirely understood. Methods: We developed a mouse model of AECOPD by cigarette smoke exposure and sequential infection with influenza H1N1 virus and non-typeable Haemophilus influenzae (NTHi). Viral and bacterial titer was determined using MDCK cells and chocolate agar plates, respectively. The levels of cytokines, adhesion molecules, and inflammatory cells in the lungs were measured using Bio-Plex and flow cytometry assays. Gut microbiota was analyzed using 16S rRNA gene sequencing. Correlations between cytokines and gut microbiota were determined using Spearman's rank correlation coefficient test. Results: Coinfection with H1N1 and NTHi resulted in more severe lung injury, higher mortality, declined lung function in COPD mice. H1N1 enhanced NTHi growth in the lungs, but NTHi had no effect on H1N1. In addition, coinfection increased the levels of cytokines and adhesion molecules, as well as immune cells including total and M1 macrophages, neutrophils, monocytes, NK cells, and CD4 + T cells. In contrast, alveolar macrophages were depleted. Furthermore, coinfection caused a decline in the diversity of gut bacteria. Muribaculaceae, Lactobacillus, Akkermansia, Lachnospiraceae, and Rikenella were further found to be negatively correlated with cytokine levels, whereas Bacteroides was positively correlated. Conclusion: Coinfection with H1N1 and NTHi causes a deterioration in COPD mice due to increased lung inflammation, which is correlated with dysbiosis of the gut microbiota.

Compounds from Arnebia euchroma and their related anti-HCV and antibacterial activities.

Three new hydroquinone terpenoids with benzogeijerene skeletons, euchroquinols A-C (1- 3), and a new monoterpenylbenzenoid, 9,17-epoxyarnebinol (4), along with five known compounds were isolated from the stem bark of ARNEBIA EUCHROMA. Shikonin (6) exhibited potent anti-HCV activity with a selective index of 43.56, and compounds 1, 6, and des-O-methyllasiodiplodin (7) showed anti-Staphylococcus aureus activity with MICs of 0.5, 0.125, and 0.125 mg/mL, respectively.

[The different epidemic and evolution of HCV genotypes].

Hepatitis C virus (HCV) is a prevalent and globally distributed human pathogen that currently infects an estimated 170 million people. Chronic HCV infection significantly increases the risk of chronic hepatitis. The virus exhibits a very high degree of genetic diversity that is classified six genotypes and sub-classified more than 80 subtypes by phylogenetic analysis. The various genotypes and subtypes of HCV have been associated with different epidemiological and geographical spread patterns. Genotypes 1 and 2 are globally distributed; genotype 3 is predominant in Asia, North America and parts of Europe; similar regional patterns of endemic diversity have been found for genotype 4 in Europe, Middle East and Central Africa, for genotype 5 in parts of Africa and Europe, and for genotype 6 in Southeast Asia and North America. Up to date, four HCV genotypes, including genotype 1, 2, 3 and 6, were identified in China. Genotypes 1b and 2a were mainly found in Northern China. The fast spreading of genotypes 3 and 6 in Southern and South-Western China was reported by recent studies. It's deduced that Yunnan may become an important source of HCV epidemic and spread, which will cause great changes in the distribution of HCV genotypes and subtypes, and a variety of transmission. With the development of evolution theory and related analysis methods, such as coalescent theory and evolutionary molecular, it is possible to understand the characters of virus evolution and migration. For HCV, the further understanding on the prevalence and evolution characters of various genotypes is very important for the deep investigation of HCV epidemic and the development of prevention strategy.

Identifying and Exploring the Candidate Susceptibility Genes of Cirrhosis Using the Multi-Tissue Transcriptome-Wide Association Study.

Objective: We identify and explore the candidate susceptibility genes for cirrhosis and their underlying biological mechanism. Methods: We downloaded the genome-wide association studies summary data of 901 cirrhosis cases and 451,363 controls and integrated them with reference models of five potential tissues from the Genotype-Tissue Expression (GTEx) Project, including whole blood, liver, pancreas, spleen, and thyroid, to identify genes whose expression is predicted to be associated with cirrhosis. Then, we downloaded gene expression data of individuals with hepatocellular carcinoma from TCGA database to conduct differential expression analysis to validate these identified genes and explored their possible role in driving cirrhosis via functional enrichment and gene set enrichment analysis (GSEA). Results: We identified 10 significant genes (SKIV2L, JPH4, UQCC2, RP11-91I8.3, MAU2, ERAP1, PUS3, ZNF677, ARHGAP40, and SHANK3) associated with cirrhosis at a Bonferroni-corrected threshold of p < 0.01, among which two (SKIV2L and JPH4) were identified in the liver and five (SKIV2L, JPH4, MAU2, SHANK3, and UQCC2) were validated by differential expression analysis at an FDR-corrected threshold of p < 0.01. The enrichment analysis showed that the degradation process of RNA, which is enriched by 58 genes, is significantly under-enriched in liver cancer tissues (p = 0.0268). Conclusion: We have identified several candidate genes for cirrhosis in multiple tissues and performed differential genetic analysis using the liver cancer database to verify the significant genes. We found that the genes SKIV2L and JPH4 identified in the liver are of particular concern. Finally, through enrichment analysis, we speculate that the process of mRNA transcription and RNA degradation may play a role in cirrhosis.

Unusual matrine-adenine hybrids isolated from Sophora davidii and their inhibitory effects on human cytomegalovirus.

A phytochemical investigation on the flowers of Sophora davidii resulted in the isolation of three unusual matrine-adenine hybrids, sophovicines A-C, together with biogenetically related analogue sophocarpine. Their structures and absolute configurations were determined by NMR analysis, single-crystal X-ray diffraction, and electronic circular dichroism (ECD) data. Since sophovicines represent the first example of matrine-adenine hybrids, a putative biosynthetic pathway toward sophovicines A-C was proposed. In addition, computational molecular modeling suggested that compounds sophovicines B and C may have potent activities against human cytomegalovirus (HCMV). So, the inhibit effects of isolates on HCMV were evaluated. The results show that sophovicines B and C can inhibit HCMV replication effectively with IC50 values of 7.12 and 7.32 µM, respectively.

Malaria: elimination tale from Yunnan Province of China and new challenges for reintroduction.

BACKGROUND: Eradication of infectious disease is the sanctified public health and sustainable development goal around the world. MAIN BODY: Three antimalarial barriers were developed to control imported malarial cases, and an effective surveillance strategy known as the "1-3-7 approach" was developed to eliminate malaria from the Chinese population. From 2011 to 2019, 5254 confirmed malaria cases were reported and treated in Yunnan Province, China. Among them, 4566 cases were imported from other countries, and 688 cases were indigenous from 2011 to 2016. Since 2017, no new local malarial case has been reported in China. Thus, malaria has been completely eliminated in Yunnan Province. However, malaria is detected in overseas travellers on a regular basis, such as visitors from neighbouring Myanmar. CONCLUSION: Hence, the strategies should be further strengthened to maintain a robust public health infrastructure for disease surveillance and vector control programs in border areas. Such programs should be supported technically and financially by the government to avert the possibility of a malarial resurgence in Yunnan Province.

Cathelicidin-DM is an Antimicrobial Peptide from Duttaphrynus melanostictus and Has Wound-Healing Therapeutic Potential.

Antimicrobial peptides (AMPs) are a class of templates with application potential for drug development. Amphibians are important sources of AMPs. Duttaphrynus melanostictus is the main source of traditional Chinese medicine "Chansu", which has anti-infection effect while without a clear mechanism. This study aimed to find the cathelicidin peptide in D. melanostictus and then investigate the activity in vivo and in vitro, and an AMP-encoding gene (cathelicidin-DM, GenBank: KJ820824.1) was obtained from the constructed cDNA library of D. melanostictus. The MIC test and SYTOX Green uptake were used for the evaluation of the bactericidal capacity and mechanisms. The serum stability tests were used for the evaluation of the application potential. The skin wound infection model and in vivo imaging were used for in vitro application of possibility evaluation. The results showed that cathelicidin-DM was a 37 amino acid AMP with good bactericidal ability, which was similar to melittin: both can kill bacteria within 15 min. Moreover, cathelicidin-DM exhibits good therapeutic potential in the mouse wound infection model, and it can be enriched to the site of infection for treatment. Thus, cathelicidin-DM could be a new template for antimicrobial drug development given its good antibacterial activity in vivo and in vitro.

CelB is a suitable marker for rapid and specific identification of Klebsiella pneumoniae by the loop-mediated isothermal amplification (LAMP) assay.

Klebsiella pneumoniae belongs to Enterobacteriaceae, which is the commonest bacterium causing nosocomial respiratory tract infection. It ranks second in bacteremia and urinary tract infection in gram-negative bacteria. Therefore, the rapid and accurate identification of K. pneumoniae was of great significance for the guide of clinical medication, and timely treatment of patients. The purpose of this study was to establish a rapid and sensitive molecular detection method for K. pneumoniae based on loop-mediated isothermal amplification (LAMP) technology. Firstly, local BLAST and NCBI BLAST were used to analyze the genome of K. pneumoniae. According to the principle of interspecific and intraspecific specificity, CelB (GenBank ID 11847805) was selected as the specific gene. Then, the LAMP and PCR identification systems were established with this target gene. Thirty-six clinical isolates of K. pneumoniae and 50 non-K. pneumoniae were used for the specific evaluation, and both LAMP and PCR could specifically distinguish K. pneumoniae from non-K. pneumoniae. A 10-fold series diluted positive plasmids and simulated infected blood samples were used as the templates in the sensitivity assay, and the results showed that the sensitivity could reach 1 copy/reaction. In summary, a rapid, specific, and sensitive LAMP method was established to detect K. pneumoniae in clinics.

Establishment of loop-mediated isothermal amplification for rapid detection of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is one of the three most pathogenic bacteria that frequently cause life-threatening opportunistic human infections, pneumonia, and lower respiratory tract infections in immunocompromised hosts, particularly in the burns ward. The present study aimed to establish a loop-mediated isothermal amplification (LAMP) method for the rapid and sensitive detection of P. aeruginosa-specific gene hypothetical protein (GenBank ID: 882161). The gene was obtained through local and online BLAST, and specific primers were designed for this gene. Reaction conditions were optimized at 65°C for 30 min and 80°C for 2 min, whereas the reaction system contained 5.2 mM Mg2+, 8 U Bst 2.0 DNA polymerase, 1.4 mM deoxyribonucleotide and 0.2 and 1.6 µM of the outer and inner primers, respectively. The LAMP method was evaluated using 150 P. aeruginosa and 170 non-P. aeruginosa strains. Positive reactions were observed on 150 P. aeruginosa strains, whereas all non-P. aeruginosa strains exhibited negative results. Plasmids with the specific gene and mouse blood with P. aeruginosa were used for sensitivity assay. The detection limit of LAMP was 1 bacterium/reaction. Results indicated that the LAMP method targeted to hypothetical protein is a fast, specific, sensitive, inexpensive and suitable method for detection of P. aeruginosa.

The Susceptibility of Primary Dermis Fibroblasts from the Chinese Tree Shrew to Human Cytomegalovirus Infection.

As a universal pathogen leading to neonatal defects and transplant failure, human cytomegalovirus (HCMV) has strict species specificity and this has prevented the development of a suitable animal model for the pathogenesis study. The mechanism of cross-species barrier remains elusive and there are so far no non-human cell culture models that support HCMV replication. The Chinese tree shrew (Tupaia belangeri chinensis) is a small laboratory animal and evolutionary closely related with primates. We investigated the susceptibility of primary tree shrew dermis fibroblasts (TSDF) to HCMV infection. Infection with a GFP-expressing HCMV virus resulted in green fluorescence in infected cells with the expression of IE1, UL44 and pp28. The titers of cell-free viruses reached 103 PFU/mL at 96 hpi, compared to titers of 104 PFU/mL observed in primary human foreskin fibroblasts. Our results suggested that TSDF was semi-permissive for HCMV infection. The TSDF model could be further used to investigate key factors influencing cross-species multiplication of HCMV.

Infectivity of Zika virus on primary cells support tree shrew as animal model.

Zika virus (ZIKV) is a mosquito-borne flavivirus that caused the public health emergency. Recently, we have proved a novel small animal tree shrew was susceptive to ZIKV infection and presented the most common rash symptoms as ZIKV patients. Here we further cultured the primary cells from different tissues of this animal to determine the tissue tropism of ZIKV infection in vitro. The results showed that the primary cells from tree shrew kidney, lung, liver, skin and aorta were permissive to ZIKV infection and could support viral replication by the detection of viral specific RNA intra- and extra-cells. In comparing, the skin fibroblast and vascular endothelial cells were highly permissive to ZIKV infection with high releasing of active virus particles in supernatants proved by its infectivity in established neonatal mouse model. The expressions of ZIKV envelop and nonstructural protein-1, and the effects and strong immune response of primary tree shrew cells were also detected followed by ZIKV infection. These findings provide powerful in vitro cell-level evidence to support tree shrew as animal model of ZIKV infection and may help to explain the rash manifestations in vivo.

Vitamin D binding protein polymorphisms influence susceptibility to hepatitis C virus infection in a high-risk Chinese population.

Vitamin D binding protein (VDBP) plays an important role in the immune modulation and pathogenesis of hepatitis C viral (HCV) infection by influencing serum vitamin D levels. The present study aims to evaluate the association of VDBP genetic polymorphisms with susceptibility to and chronicity of HCV infection in a high-risk Chinese population. Seven genetic variants in the VDBP gene were genotyped in a case-control study of 886 patients with HCV persistent infection, 539 subjects with spontaneous clearance, and 1081 uninfected controls. Logistic regression analysis was used to assess the effects of these variants on HCV infection outcomes. The results showed that two variants rs7041-G and rs3733359-T alleles were significantly associated with increased susceptibility of HCV infection, and the combined effect of the two unfavorable alleles was related to an elevated risk of HCV infection in a locus-dosage manner (Ptrend = 8.16 × 10-4). Interaction analysis manifested that rs7041-GT/GG and rs3733359-CT/TT jointly increased risk of HCV infection. Moreover, haplotype analysis suggested that compared with the most frequent TC haplotype, the haplotype carrying GT indicated a risk effect of HCV infection [odds ratio (OR) = 1.464]. However, no significant associations were observed for the other five variants. These findings implied that VDBP rs7041-G and rs3733359-T variants may contribute to increased susceptibility to HCV infection in a high-risk Chinese population.

The role of interleukin-1ß and extracellular signal-regulated kinase 1/2 in glucose-stimulated insulin secretion.

Glucose-stimulated insulin secretion (GSIS) is one of the important physiological characteristics of islet ß cells, and extracellular-regulated protein kinase 1/2 (ERK1/2) is an important member of the mitogen-activated protein kinase family that regulates this process. The inflammatory cytokine interleukin (IL)-1ß can inhibit the insulin secretion of pancreatic ß cells, but the exact mechanism is unclear. This study was designed to investigate the inhibitory effect of IL-1ß on GSIS in ßTC-6 cells and its relation with the ERK1/2 signal transduction pathway. ß-TC6 cells were cultured and stimulated with 0mM, 1.38mM, or 5.5mM glucose. In addition, GSIS in ß-TC6 cells was blocked by IL-1ß at concentrations of 0.15 ng/mL, 1.5 ng/mL, and 15 ng/mL. After glucose stimulation and IL-1ß intervention, the insulin level in the cell supernatant was detected by radioimmunoassay, and the phosphorylation level of ERK1/2 was detected by western blotting assay. The insulin level in the 1.38mM glucose group was 108.52 ± 5.94 uIU/mL, which was significantly higher than the 0mM and 5.5mM glucose groups (p < 0.05). Compared with the 0mM glucose group, the level of ERK1/2 phosphorylation was increased in the 1.38mM and 5.5mM glucose groups. After intervention by 0.15 ng/mL, 1.5 ng/mL, and 15 ng/mL IL-1ß, the level of ERK1/2 phosphorylation induced by 1.38mM glucose stimulation decreased in a dose-dependent manner, and the insulin level correspondingly decreased. IL-1ß can inhibit GSIS in ßTC-6 cells, which is related to its inhibition of the phosphorylation of ERK1/2.

Anterograde monosynaptic transneuronal tracers derived from herpes simplex virus 1 strain H129.

BACKGROUND: Herpes simplex virus type 1 strain 129 (H129) has represented a promising anterograde neuronal circuit tracing tool, which complements the existing retrograde tracers. However, the current H129 derived tracers are multisynaptic, neither bright enough to label the details of neurons nor capable of determining direct projection targets as monosynaptic tracer. METHODS: Based on the bacterial artificial chromosome of H129, we have generated a serial of recombinant viruses for neuronal circuit tracing. Among them, H129-G4 was obtained by inserting binary tandemly connected GFP cassettes into the H129 genome, and H129-ΔTK-tdT was obtained by deleting the thymidine kinase (TK) gene and adding tdTomato coding gene to the H129 genome. Then the obtained viral tracers were tested in vitro and in vivo for the tracing capacity. RESULTS: H129-G4 is capable of transmitting through multiple synapses, labeling the neurons by green florescent protein, and visualizing the morphological details of the labeled neurons. H129-ΔTK-tdT neither replicates nor spreads in neurons alone, but transmits to and labels the postsynaptic neurons with tdTomato in the presence of complementary expressed TK from a helper virus. H129-ΔTK-tdT is also capable to map the direct projectome of the specific neuron type in the given brain regions in Cre transgenic mice. In the tested brain regions where circuits are well known, the H129-ΔTK-tdT tracing patterns are consistent with the previous results. CONCLUSIONS: With the assistance of the helper virus complimentarily expressing TK, H129-ΔTK-tdT replicates in the initially infected neuron, transmits anterogradely through one synapse, and labeled the postsynaptic neurons with tdTomato. The H129-ΔTK-tdT anterograde monosynaptic tracing system offers a useful tool for mapping the direct output in neuronal circuitry. H129-G4 is an anterograde multisynaptic tracer with a labeling signal strong enough to display the details of neuron morphology.