Disrupting the olfactory response in Monochamus saltuarius: Two potential target genes for controlling the vector insect of pine wilt disease.

Worldwide, pine forests have been threatened by a devastating pine wood disease caused by Bursaphelenchus xylophilus, with Monochamus saltuarius being a newly recorded vector of the disease in Northeast China. The olfactory system plays important roles in both feeding and oviposition during the adult stage of M. saltuarius, and olfactory gene function research is essential for gaining an understanding of the olfactory mechanisms of this pest. However, there is limited information available regarding olfactory gene functions in this pest. In the present study, we selected 7 olfactory genes, including 2 chemosensory proteins, 2 odorant-binding proteins, the odorant co-receptor and 2 odorant receptors, which were relatively highly expressed during the adult stage. We silenced these genes by RNA interference (RNAi), and real-time quantitative PCR was used to detect their expression levels after double-stranded RNA (dsRNA) injection. The results indicate that these genes were significantly downregulated at 2 d post-dsRNA injection, and this was sustained until 5 d post-injection. Electroantennography tests indicated that the knockdown of MsalOBP14 and MsalOrco impaired the olfactory response of M. saltuarius to 11 host volatiles and 1 sex pheromone compound. Y-tube experiments further confirmed that downregulated MsalOBP14 and MsalOrco expression led to olfactory dysfunction in M. saltuarius, which significantly lost selectivity. The results indicate that MsalOBP14 and MsalOrco play critical roles in sex communication and host volatile detection in M. saltuarius, and possibly represent 2 effective targets for controlling this forest pest through olfactory disruption.

Enhanced sensitivity of chimeric insect olfactory co-receptors for detecting odorant molecules.

Insect olfactory receptors (ORs) are seven-transmembrane domain ion channels that function by forming heteromeric complexes with olfactory receptor co-receptors (Orcos). In this study, we investigated the potential for enhancing sensitivity of odor detection and responsivity through genetic modification of Orcos, considering its wider application in odor sensing. First, we measured the intensity of response to 1-octen-3-ol for the mosquito Aedes aegypti OR (AaOR8) when complexed individually with an Orco from the same mosquito (AaOrco), the honeybee Apis mellifera (AmOrco), the silkworm Bombyx mori (BmOrco), or the fruit fly Drosophila melanogaster (DmOrco). Relative to the other Orcos, AmOrco demonstrated higher sensitivity and responsivity, with a 1.8 to 21-fold decrease in the half-maximal effective concentration (EC50) and a 1.6-8.8-fold increase in the maximal effect (Emax), respectively. Furthermore, AmOrco co-expressed with AaOR10, BmOR56, or DmOR47a showed higher sensitivity and responsivity than AaOrco, BmOrco, or DmOrco co-expressed with their respective ORs. To further increase sensitivity and responsivity, we engineered chimeric Orcos by fusing AmOrco with DmOrco, considering the domain characteristics of Orcos. The response to 1-octen-3-ol was evaluated for AaOR8 when complexed individually with AmOrco, as well as for a mutant that combines DmOrco from the N-terminal (NT) to the C-terminal region of the fourth transmembrane domain (TM4) with the region of AmOrco following TM4 (Dm[NT-TM4]AmOrco). When compared to AmOrco, Dm(NT-TM4)AmOrco showed higher sensitivity and responsivity, with a 1.4-fold decrease in the EC50 and a 1.4-fold increase in the Emax, respectively. In addition, Dm(NT-TM4)AmOrco co-expressed with either DmOR47a or BmOR56 demonstrated higher sensitivity and responsivity than AmOrco co-expressed with their respective ORs. These results suggest that AmOrco could be a relatively more sensitive Orco, and further enhancement of sensitivity and responsivity could be achieved through recombination with heterologous Orcos near the TM4 of AmOrco.

A spatiotemporal map of co-receptor signaling networks underlying B cell activation.

The B cell receptor (BCR) signals together with a multi-component co-receptor complex to initiate B cell activation in response to antigen binding. Here, we take advantage of peroxidase-catalyzed proximity labeling combined with quantitative mass spectrometry to track co-receptor signaling dynamics in Raji cells from 10 s to 2 h after BCR stimulation. This approach enables tracking of 2,814 proximity-labeled proteins and 1,394 phosphosites and provides an unbiased and quantitative molecular map of proteins recruited to the vicinity of CD19, the signaling subunit of the co-receptor complex. We detail the recruitment kinetics of signaling effectors to CD19 and identify previously uncharacterized mediators of B cell activation. We show that the glutamate transporter SLC1A1 is responsible for mediating rapid metabolic reprogramming and for maintaining redox homeostasis during B cell activation. This study provides a comprehensive map of BCR signaling and a rich resource for uncovering the complex signaling networks that regulate activation.

Development and Validation of a Genotypic Assay to Quantify CXCR4- and CCR5-Tropic Human Immunodeficiency Virus Type-1 (HIV-1) Populations and a Comparison to Trofile®.

HIV-1 typically infects cells via the CD4 receptor and CCR5 or CXCR4 co-receptors. Maraviroc is a CCR5-specific viral entry inhibitor; knowledge of viral co-receptor specificity is important prior to usage. We developed and validated an economical V3-env Illumina-based assay to detect and quantify the frequency of viruses utilizing each co-receptor. Plasma from 54 HIV+ participants (subtype B) was tested. The viral template cDNA was generated from plasma RNA with unique molecular identifiers (UMIs). The sequences were aligned and collapsed by the UMIs with a custom bioinformatics pipeline. Co-receptor usage, determined by codon analysis and online phenotype predictors PSSM and Geno2pheno, were compared to existing Trofile® data. The cost of V3-UMI was tallied. The sequences interpreted by Geno2pheno using the most conservative cut-off, a 2% false-positive-rate (FPR), predicted CXCR4 usage with the greatest sensitivity (76%) and specificity (100%); PSSM and codon analysis had similar sensitivity and lower specificity. Discordant Trofile® and genotypic results were more common when participants had specimens from different dates analyzed by either assay. V3-UMI reagents cost USD$62/specimen. A batch of ≤20 specimens required 5 h of technical time across 1.5 days. V3-UMI predicts HIV tropism at a sensitivity and specificity similar to those of Trofile®, is relatively inexpensive, and could be performed by most central laboratories. The adoption of V3-UMI could expand HIV drug therapeutic options in lower-resource settings that currently do not have access to phenotypic HIV tropism testing.

Transceptor NRT1.1 and receptor-kinase QSK1 complex controls PM H+-ATPase activity under low nitrate.

NRT1.1, a nitrate transceptor, plays an important role in nitrate binding, sensing, and nitrate-dependent lateral root (LR) morphology. However, little is known about NRT1.1-mediated nitrate signaling transduction through plasma membrane (PM)-localized proteins. Through in-depth phosphoproteome profiling using membranes of Arabidopsis roots, we identified receptor kinase QSK1 and plasma membrane H+-ATPase AHA2 as potential downstream components of NRT1.1 signaling in a mild low-nitrate (LN)-dependent manner. QSK1, as a functional kinase and molecular link, physically interacts with NRT1.1 and AHA2 at LN and specifically phosphorylates AHA2 at S899. Importantly, we found that LN, not high nitrate (HN), induces formation of the NRT1.1-QSK1-AHA2 complex in order to repress the proton efflux into the apoplast by increased phosphorylation of AHA2 at S899. Loss of either NRT1.1 or QSK1 thus results in a higher T947/S899 phosphorylation ratio on AHA2, leading to enhanced pump activity and longer LRs under LN. Our results uncover a regulatory mechanism in which NRT1.1, under LN conditions, promotes coreceptor QSK1 phosphorylation and enhances the NRT1.1-QSK1 complex formation to transduce LN sensing to the PM H+-ATPase AHA2, controlling the phosphorylation ratio of activating and inhibitory phosphorylation sites on AHA2. This then results in altered proton pump activity, apoplast acidification, and regulation of NRT1.1-mediated LR growth.

Distinct genetic clusters in HIV-1 CRF01_AE-infected patients induced variable degrees of CD4+ T-cell loss.

CRF01_AE strains have been shown to form multiple transmission clusters in China, and some clusters have disparate pathogenicity in Chinese men who have sex with men. This study focused on other CRF01_AE clusters prevalent in heterosexual populations. The CD4+ T-cell counts from both cross-section data in National HIV Molecular Epidemiology Survey and seropositive cohort data were used to evaluate the pathogenicity of the CRF01_AE clusters and other HIV-1 sub-types. Their mechanisms of pathogenicity were evaluated by co-receptor tropisms, predicted by genotyping and confirmed with virus isolate phenotyping, as well as inflammation parameters. Our research elucidated that individuals infected with CRF01_AE clusters 1 and 2 exhibited significantly lower baseline CD4+ T-cell counts and greater CD4+ T-cell loss in cohort follow-up, compared with other HIV-1 sub-types and CRF01_AE clusters. The increased pathogenesis of cluster 1 or 2 was associated with higher CXCR4 tropisms, higher inflammation/immune activation, and increased pyroptosis. The protein structure modeling analysis revealed that the envelope V3 loop of clusters 1 and 2 viruses is favorable for CXCR4 co-receptor usage. Imbedded with the most mutating reverse transcriptase, HIV-1 is one of the most variable viruses. CRF01_AE clusters 1 and 2 have been found to have evolved into more virulent strains in regions with predominant heterosexual infections. The virulent strains increased the pressure for early diagnosis and treatment in HIV patients. To save more lives, HIV-1 surveillance systems should be upgraded from serology and genotyping to phenotyping, which could support precision interventions for those infected by virulent viruses. IMPORTANCE: Retroviruses swiftly adapt, employing error-prone enzymes for genetic and phenotypic evolution, optimizing survival strategies, and enhancing virulence levels. HIV-1 CRF01_AE has persistently undergone adaptive selection, and cluster 1 and 2 infections display lower counts and fast loss of CD4+ T cells than other HIV-1 sub-types and CRF01_AE clusters. Its mechanisms are associated with increased CXCR4 tropism due to an envelope structure change favoring a tropism shift from CCR5 to CXCR4, thereby shaping viral phenotype features and impacting pathogenicity. This underscores the significance of consistently monitoring HIV-1 genetic evolution and phenotypic transfer to see whether selection bias across risk groups alters the delicate balance of transmissible versus toxic trade-offs, since virulent strains such as CRF01_AE clusters 1 and 2 could seriously compromise the efficacy of antiviral treatment. Only through such early warning and diagnostic services can precise antiviral treatments be administered to those infected with more virulent HIV-1 strains.

Medicinal chemistry perspectives on the development of piperazine-containing HIV-1 inhibitors.

The Human immunodeficiency virus (HIV) is the causative agent of acquired immunodeficiency syndrome (AIDS), one of the most perilous diseases known to humankind. A 2023 estimate put the number of people living with HIV around 40 million worldwide, with the majority benefiting from various antiretroviral therapies. Consequently, the urgent need for the development of effective drugs to combat this virus cannot be overstated. In the realm of medicinal and organic chemistry, the synthesis and identification of novel compounds capable of inhibiting HIV enzymes at different stages of their life cycle are of paramount importance. Notably, the spotlight is on the progress made in enhancing the potency of HIV inhibitors through the use of piperazine-based compounds. Multiple studies have revealed that the incorporation of a piperazine moiety results in a noteworthy enhancement of anti-HIV activity. The piperazine ring assumes a pivotal role in shaping the pharmacophore responsible for inhibiting HIV-1 at critical stage, including attachment, reverse transcription, integration, and protease activity. This review also sheds light on the various opportunities that can be exploited to develop effective antiretroviral targets and eliminate latent HIV reservoirs. The advancement of highly potent analogues in HIV inhibitor research has been greatly facilitated by contemporary medicinal strategies, including molecular/fragment hybridization, structure-based drug design, and bioisosterism. These techniques have opened up new avenues for the development of compounds with enhanced efficacy in combating the virus.

The Orco gene involved in recognition of host plant volatiles and sex pheromone in the chive maggot Bradysia odoriphaga.

The insect olfactory recognition system plays a crucial role in the feeding and reproductive behaviors of insects. The odorant receptor co-receptor (Orco), as an obligatory chaperone, is critical for odorant recognition by way of forming heteromeric complexes with conventional odorant receptors (ORs). To investigate the biological functions of Orco in perceiving host plant volatiles and sex pheromone, the Orco gene was identified from the chive maggot Bradysia odoriphaga transcriptome data. Multiple sequence alignment reveals that BodoOrco exhibits an extremely high sequence identity with Orcos from other dipteran insects. The expression of BodoOrco is significantly higher in adults than in larvae and pupae, and the BodoOrco gene is primarily expressed in the antennae of both sexes. Furthermore, the Y-tube assay indicated that knockdown of BodoOrco leads to significant reductions in B. odoriphaga adults' response to all tested host plant volatiles. The dsOrco-treated unmated male adults show less attraction to unmated females and responded slowly compared with dsGFP control group. These results indicated that BodoOrco is involved in recognition of sex pheromone and host plant volatiles in B. odoriphaga and has the potential to be used as a target for the design of novel active compounds for developing ecofriendly pest control strategies.

A Novel Biallelic LCK Variant Resulting in Profound T-Cell Immune Deficiency and Review of the Literature.

Lymphocyte-specific protein tyrosine kinase (LCK) is an SRC-family kinase critical for initiation and propagation of T-cell antigen receptor (TCR) signaling through phosphorylation of TCR-associated CD3 chains and recruited downstream molecules. Until now, only one case of profound T-cell immune deficiency with complete LCK deficiency [1] caused by a biallelic missense mutation (c.1022T>C, p.L341P) and three cases of incomplete LCK deficiency [2] caused by a biallelic splice site mutation (c.188-2A>G) have been described. Additionally, deregulated LCK expression has been associated with genetically undefined immune deficiencies and hematological malignancies. Here, we describe the second case of complete LCK deficiency in a 6-month-old girl born to consanguineous parents presenting with profound T-cell immune deficiency. Whole exome sequencing (WES) revealed a novel pathogenic biallelic missense mutation in LCK (c.1393T>C, p.C465R), which led to the absence of LCK protein expression and phosphorylation, and a consecutive decrease in proximal TCR signaling. Loss of conventional CD4+ and CD8+ αßT-cells and homeostatic T-cell expansion was accompanied by increased γδT-cell and Treg percentages. Surface CD4 and CD8 co-receptor expression was reduced in the patient T-cells, while the heterozygous mother had impaired CD4 and CD8 surface expression to a lesser extent. We conclude that complete LCK deficiency is characterized by profound T-cell immune deficiency, reduced CD4 and CD8 surface expression, and a characteristic TCR signaling disorder. CD4 and CD8 surface expression may be of value for early detection of mono- and/or biallelic LCK deficiency.

Tracking coreceptor switch of the transmitted/founder HIV-1 identifies co-evolution of HIV-1 antigenicity, coreceptor usage and CD4 subset targeting: the RV217 acute infection cohort study.

BACKGROUND: The CCR5 (R5) to CXCR4 (X4) coreceptor switch in natural HIV-1 infection is associated with faster progression to AIDS, but the mechanisms remain unclear. The difficulty in elucidating the evolutionary origin of the earliest X4 viruses limits our understanding of this phenomenon. METHODS: We tracked the evolution of the transmitted/founder (T/F) HIV-1 in RV217 participants identified in acute infection. The origin of the X4 viruses was elucidated by single genome amplification, deep sequencing and coreceptor assay. Mutations responsible for coreceptor switch were confirmed by mutagenesis. Viral susceptibility to neutralization was determined by neutralization assay. Virus CD4 subset preference was demonstrated by sequencing HIV-1 RNA in sorted CD4 subsets. FINDINGS: We demonstrated that the earliest X4 viruses evolved de novo from the T/F strains. Strong X4 usage can be conferred by a single mutation. The mutations responsible for coreceptor switch can confer escape to neutralization and drive the X4 variants to replicate mainly in the central memory (CM) and naïve CD4 subsets. Likely due to the smaller viral burst size of the CM and naïve subsets, the X4 variants existed at low frequency in plasma. The origin of the X4 viruses preceded accelerated CD4 decline. All except one X4 virus identified in the current study lost the conserved V3 N301 glycan site. INTERPRETATIONS: The findings demonstrate co-evolution of HIV-1 antigenicity, coreceptor usage and CD4 subset targeting which have implications for HIV-1 therapeutics and functional cure. The observations provide evidence that coreceptor switch can function as an evolutionary mechanism of immune evasion. FUNDING: Institute of Human Virology, National Institutes of Health, Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc, Thai Red Cross AIDS Research Centre, Gilead Sciences, Merck, and ViiV Healthcare.

Galectin-14 promotes hepatocellular carcinoma tumor growth via enhancing heparan sulfate proteoglycan modification.

Hepatocellular carcinoma (HCC) is a highly heterogeneous malignancy and lacks effective treatment. Bulk-sequencing of different gene transcripts by comparing HCC tissues and adjacent normal tissues provides some clues for investigating the mechanisms or identifying potential targets for tumor progression. However, genes that are exclusively expressed in a subpopulation of HCC may not be enriched or detected through such a screening. In the current study, we performed a single cell-clone-based screening and identified galectin-14 as an essential molecule in the regulation of tumor growth. The aberrant expression of galectin-14 was significantly associated with a poor overall survival of liver cancer patients with database analysis. Knocking down galectin-14 inhibited the proliferation of tumor growth, whereas overexpressing galectin-14 promoted tumor growth in vivo. Non-targeted metabolomics analysis indicated that knocking down galectin-14 decreased glycometabolism; specifically that glycoside synthesis was significantly changed. Further study found that galectin-14 promoted the expression of cell surface heparan sulfate proteoglycans (HSPGs) that functioned as co-receptors, thereby increasing the responsiveness of HCC cells to growth factors, such as epidermal growth factor and transforming growth factor-alpha. In conclusion, the current study identifies a novel HCC-specific molecule galectin-14, which increases the expression of cell surface HSPGs and the uptake of growth factors to promote HCC cell proliferation.

Difference in the ligand affinity among redundant plant hormone receptors of rice OsCOI1a/1b/2-OsJAZs.

(3R, 7S)-jasmonoyl-L-isoleucine (JA-Ile) is a lipid-derived plant hormone that regulates plant responses, including biotic/abiotic stress adaptation. In the plant cells, JA-Ile is perceived by COI1-JAZ co-receptor by causing protein-protein interaction between COI1 and JAZ proteins to trigger gene expressions. In this study, we focused on Oryza sativa, a model monocot and an important crop, with 45 possible OsCOI-OsJAZ co-receptor pairs composed of three OsCOI homologs (OsCOI1a, OsCOI1b, and OsCOI2) and 15 OsJAZ homologs. We performed fluorescein anisotropy and pull-down assays to examine the affinity between JA-Ile and OsCOI1a/1b/2-OsJAZ1-15 co-receptor pairs. The results revealed a remarkable difference in the modes of ligand perception by OsCOI1a/1b and OsCOI2. Recently, the unique function of OsCOI2 in some of the JA-responses were revealed. Our current results will lead to the possible development of OsCOI2-selective synthetic ligand.

A phospho-switch constrains BTL2-mediated phytocytokine signaling in plant immunity.

Enabling and constraining immune activation is of fundamental importance in maintaining cellular homeostasis. Depleting BAK1 and SERK4, the co-receptors of multiple pattern recognition receptors (PRRs), abolishes pattern-triggered immunity but triggers intracellular NOD-like receptor (NLR)-mediated autoimmunity with an elusive mechanism. By deploying RNAi-based genetic screens in Arabidopsis, we identified BAK-TO-LIFE 2 (BTL2), an uncharacterized receptor kinase, sensing BAK1/SERK4 integrity. BTL2 induces autoimmunity through activating Ca2+ channel CNGC20 in a kinase-dependent manner when BAK1/SERK4 are perturbed. To compensate for BAK1 deficiency, BTL2 complexes with multiple phytocytokine receptors, leading to potent phytocytokine responses mediated by helper NLR ADR1 family immune receptors, suggesting phytocytokine signaling as a molecular link connecting PRR- and NLR-mediated immunity. Remarkably, BAK1 constrains BTL2 activation via specific phosphorylation to maintain cellular integrity. Thus, BTL2 serves as a surveillance rheostat sensing the perturbation of BAK1/SERK4 immune co-receptors in promoting NLR-mediated phytocytokine signaling to ensure plant immunity.

The biology of SCUBE.

The SCUBE [Signal peptide-Complement C1r/C1s, Uegf, Bmp1 (CUB)-Epithelial growth factor domain-containing protein] family consists of three proteins in vertebrates, SCUBE1, 2 and 3, which are highly conserved in zebrafish, mice and humans. Each SCUBE gene encodes a polypeptide of approximately 1000 amino acids that is organized into five modular domains: (1) an N-terminal signal peptide sequence, (2) nine tandem epidermal growth factor (EGF)-like repeats, (3) a large spacer region, (4) three cysteine-rich (CR) motifs, and (5) a CUB domain at the C-terminus. Murine Scube genes are expressed individually or in combination during the development of various tissues, including those in the central nervous system and the axial skeleton. The cDNAs of human SCUBE orthologs were originally cloned from vascular endothelial cells, but SCUBE expression has also been found in platelets, mammary ductal epithelium and osteoblasts. Both soluble and membrane-associated SCUBEs have been shown to play important roles in physiology and pathology. For instance, upregulation of SCUBEs has been reported in acute myeloid leukemia, breast cancer and lung cancer. In addition, soluble SCUBE1 is released from activated platelets and can be used as a clinical biomarker for acute coronary syndrome and ischemic stroke. Soluble SCUBE2 enhances distal signaling by facilitating the secretion of dual-lipidated hedgehog from nearby ligand-producing cells in a paracrine manner. Interestingly, the spacer regions and CR motifs can increase or enable SCUBE binding to cell surfaces via electrostatic or glycan-lectin interactions. As such, membrane-associated SCUBEs can function as coreceptors that enhance the signaling activity of various serine/threonine kinase or tyrosine kinase receptors. For example, membrane-associated SCUBE3 functions as a coreceptor that promotes signaling in bone morphogenesis. In humans, SCUBE3 mutations are linked to abnormalities in growth and differentiation of both bones and teeth. In addition to studies on human SCUBE function, experimental results from genetically modified mouse models have yielded important insights in the field of systems biology. In this review, we highlight novel molecular discoveries and critical directions for future research on SCUBE proteins in the context of cancer, skeletal disease and cardiovascular disease.

A Leucine-Rich Repeat Receptor-like Kinase TaBIR1 Contributes to Wheat Resistance against Puccinia striiformis f. sp. tritici.

Plant cell surface-localized receptor-like kinases (RLKs) recognize invading pathogens and transduce the immune signals inside host cells, subsequently triggering immune responses to fight off pathogen invasion. Nonetheless, our understanding of the role of RLKs in wheat resistance to the biotrophic fungus Puccinia striiformis f. sp. tritici (Pst) remains limited. During the differentially expressed genes in Pst infected wheat leaves, a Leucine-repeat receptor-like kinase (LRR-RLK) gene TaBIR1 was significantly upregulated in the incompatible wheat-Pst interaction. qRT-PCR verified that TaBIR1 is induced at the early infection stage of Pst. The transient expression of TaBIR1-GFP protein in N. bentamiana cells and wheat mesophyll protoplasts revealed its plasma membrane location. The knockdown of TaBIR1 expression by VIGS (virus induced gene silencing) declined wheat resistance to stripe rust, resulting in reduced reactive oxygen species (ROS) production, callose deposition, and transcripts of pathogenesis-related genes TaPR1 and TaPR2, along with increased Pst infection area. Ectopic overexpression of TaBIR1 in N. benthamiana triggered constitutive immune responses with significant cell death, callose accumulation, and ROS production. Moreover, TaBIR1 triggered immunity is dependent on NbBAK1, the silencing of which significantly attenuated the defense response triggered by TaBIR1. TaBIR1 interacted with the NbBAK1 homologues in wheat, co-receptor TaSERK2 and TaSERK5, the transient expression of which could restore the impaired defense due to NbBAK1 silencing. Taken together, TaBIR1 is a cell surface RLK that contributes to wheat stripe rust resistance, probably as a positive regulator of plant immunity in a BAK1-dependent manner.

The diverse role of heparan sulfate and other GAGs in SARS-CoV-2 infections and therapeutics.

In December 2019, the global coronavirus disease 2019 (COVID-19) pandemic began in Wuhan, China. COVID-19 is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which infects host cells primarily through the angiotensin-converting enzyme 2 (ACE2) receptor. In addition to ACE2, several studies have shown the importance of heparan sulfate (HS) on the host cell surface as a co-receptor for SARS-CoV-2-binding. This insight has driven research into antiviral therapies, aimed at inhibiting the HS co-receptor-binding, e.g., by glycosaminoglycans (GAGs), a family of sulfated polysaccharides that includes HS. Several GAGs, such as heparin (a highly sulfated analog of HS), are used to treat various health indications, including COVID-19. This review is focused on current research on the involvement of HS in SARS-CoV-2 infection, implications of viral mutations, as well as the use of GAGs and other sulfated polysaccharides as antiviral agents.

Korean Red Ginseng slows coreceptor switch in HIV-1 infected patients.

Background: Human immunodeficiency virus-1 (HIV-1) that binds to the coreceptor CCR5 (R5 viruses) can evolve into viruses that bind to the coreceptor CXCR4 (X4 viruses), with high viral replication rates governing this coreceptor switch. Korean Red Ginseng (KRG) treatment of HIV-1 infected patients has been found to slow the depletion of CD4+ T cells. This study assessed whether the KRG-associated slow depletion of CD4+ T cells was associated with coreceptor switching. Methods: This study included 146 HIV-1-infected patients naïve to antiretroviral therapy (ART) and seven patients receiving ART. A total of 540 blood samples were obtained from these patients over 122 ± 129 months. Their env genes were amplified by nested PCR or RT-PCR and subjected to direct sequencing. Tropism was determined with a 10% false positive rate (FPR) cutoff. Results: Of the 146 patients naïve to ART, 102 were KRG-naïve, and 44 had been treated with KRG. Evaluation of initial samples showed that coreceptor switch had occurred in 19 patients, later occurring in 38 additional patients. There was a significant correlation between the amount of KRG and FPR. Based on initial samples, the R5 maintenance period was extended 2.35-fold, with the coreceptor switch being delayed 2.42-fold in KRG-treated compared with KRG-naïve patients. The coreceptor switch occurred in 85% of a homogeneous cohort. The proportion of patients who maintained R5 for ≥10 years was significantly higher in long-term slow progressors than in typical progressors. Conclusion: KRG therapy extends R5 maintenance period by increasing FPR, thereby slowing the coreceptor switch.

Substitution of gp120 C4 region compensates for V3 loss-of-fitness mutations in HIV-1 CRF01_AE co-receptor switching.

HIV-1 infection is mediated by a viral envelope subsequently binding to CD4 receptor and two main coreceptors, CCR5 (R5) for primary infection and CXCR4 (X4) in chronic infection. Switching from R5 to X4 tropism in HIV-1 infection is associated with increased viral pathogenesis and disease progression. The coreceptor switching is mainly due to variations in the V3 loop, while the mechanism needs to be further elucidated. We systematically studied the determinant for HIV-1 coreceptor switching by substitution of the genes from one R5 and one X4 pseudoviruses. The study results in successfully constructing two panels of chimeric viruses of R5 to X4 forward and X4 to R5 reverse switching. The determinants for tropism switching are the combined substitution of the V3 loop and C4 region of the HIV-1 envelope. The possible mechanism of the tropism switching includes two components, the V3 loop to enable the viral envelope binding to the newly switched coreceptor and the C4 region, to compensate for the loss of fitness caused by deleterious V3 loop mutations to maintain the overall viral viability. The combined C4 and V3 substitution showed at least an eightfold increase in replication activity compared with the pseudovirus with only V3 loop substitution. The site-directed mutations of N425R and S440-I442 with charged amino acids could especially increase viral activity. This study could facilitate HIV-1 phenotype surveillance and select right entry inhibitor, CCR5 or CXCR4 antagonists, for antiviral therapy.

The odorant receptor co-receptor gene contributes to mating and host-searching behaviors in parasitoid wasps.

BACKGROUND: Biological control of pest insects by parasitoid wasps is an effective and environmentally friendly strategy compared with the use of synthetic pesticides. Successful courtship and host-search behaviors of parasitoid wasps are important for biological control efficiency and are often mediated by chemical odorant cues. The odorant receptor co-receptor (Orco) gene has an essential role in the perception of odors in insects. However, the function of Orco in the mating and host-searching behaviors of parasitoid wasps remains underexplored. RESULTS: We identified the full-length Orco genes of four Drosophila parasitoid species in the genus Leptopilina, namely L. heterotoma, L. boulardi, L. syphax and L. drosophilae. Sequence alignment and membrane-topology analysis showed that Leptopilina Orcos had similar amino acid sequences and topology structures. Phylogenetic analysis revealed that Leptopilina Orcos were highly conserved. Furthermore, the results of quantitative real-time polymerase chain reactions showed that all four Orco genes had a typical antennae-biased tissue expression pattern. After knockdown of Orco in these different parasitoid species, we found that Orco-deficient male parasitoid wasps, but not females, lost their courtship ability. Moreover, Orco-deficient female parasitoid wasps presented impaired host-searching performance and decreased oviposition rates. CONCLUSION: Our study demonstrates that Orcos are essential in the mating and host-searching behaviors of parasitoid wasps. To our knowledge, this is the first time that the functions of Orco genes have been characterized in parasitoid wasps, which broadens our understanding of the chemoreception basis of parasitoid wasps and contributes to developing advanced pest management strategies. © 2022 Society of Chemical Industry.

Orco mutagenesis causes deficiencies in olfactory sensitivity and fertility in the migratory brown planthopper, Nilaparvata lugens.

BACKGROUND: The migratory brown planthopper (BPH), Nilaparvata lugens (Hemiptera: Delphacidae), is the most destructive pest affecting rice plants in Asia and feeds exclusively on rice. Studies have investigated the olfactory response of BPHs to the major rice volatile compounds in rice. The insect olfactory co-receptor (Orco) is a crucial component of the olfactory system and is essential for odorant detection. Functional analysis of the Orco gene in BPHs would aid in the identification of their host preference. RESULTS: We identified the BPH Orco homologue (NlOrco) by Blast searching the BPH transcriptome with the Drosophila Orco gene sequence. Spatiotemporal analysis indicated that NlOrco is first expressed in the later egg stage, and is expressed mainly in the antennae in adult females. A NlOrco-knockout line (NlOrco-/- ) was generated through clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated mutagenesis. The NlOrco-/- mutants showed no response to rice volatile compounds and consequently no host-plant preference. In addition, NlOrco-/- mutants exhibited extended nymphal duration and impaired fecundity compared with wild-type BPHs. CONCLUSION: Our findings indicated that BPHs exhibit strong olfactory responses to major rice volatile compounds and suggest that NlOrco is required for the maximal fitness of BPHs. Our results may facilitate the identification of potential target genes or chemical compounds for BPH control applications. © 2022 Society of Chemical Industry.