In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.

[Q]: Interferon lambda 4 (IFNλ4) has been recently known and studied for its role in hepatitis C virus (HCV) infection, but its clinical potential is significantly hampered due to its poor expression in vitro. Our study reports the successful production of IFNλ4 from a mammalian cell line through a glycoengineering and structure-based approach. We introduced de novo N-glycosylation of IFNλ4, guided by structural analysis, and produced IFNλ4 variants in Expi293F that displayed improved expression and potency. To preserve the structure and functionality of IFNλ4, the model structure of the IFNλ4 signaling complex was analyzed and the N-glycosylation candidate sites were selected. The receptor binding activity of engineered IFNλ4 variants and their receptormediated signaling pathway were similar to the E. coli version of IFNλ4 (eIFNλ4), while the antiviral activity and induction levels of interferon-stimulated gene (ISG) were all more robust in our variants. Our engineered IFNλ4 variants may be further developed for clinical applications and utilized in basic research to decipher the immunological roles of IFNλ4. Previously, the transient expression of wild-type IFNλ4 in mammalian cells failed to produce significant amounts of recombinant
[A]: Structure-based glycoengineering of interferon lambda 4 enhances its productivity and anti-viral potency


[Q]: The respiratory syncytial virus (RSV) fusion (F) glycoprotein is a major target of neutralizing antibodies arising from natural infection, and antibodies that specifically bind to the prefusion conformation of RSV F generally demonstrate the greatest neutralization potency. Prefusion-stabilized RSV F variants have been engineered as vaccine antigens, but crystal structures of these variants have revealed conformational differences in a key antigenic site located at the apex of the trimer, referred to as antigenic site Ø. Currently, it is unclear if flexibility in this region is an inherent property of prefusion RSV F or if it is related to inadequate stabilization of site Ø in the engineered variants. Therefore, we set out to investigate the conformational flexibility of antigenic site Ø, as well as the ability of the human immune system to recognize alternative conformations of this site, by determining crystal structures of prefusion RSV F bound to neutralizing human-derived antibodies AM22 and RSD5. Both antibodies bound with high affinity and were specific for the prefusion conformation of RSV F. Crystal structures of the complexes revealed that the antibodies recognized distinct conformations of antigenic site Ø, each diverging at a conserved proline residue located in the middle of an α-helix. These data suggest that antigenic site Ø exists as an ensemble of conformations, with individual antibodies recognizing discrete states. Collectively, these results have implications for the refolding of pneumovirus and paramyxovirus fusion proteins and should inform development of prefusion-stabilized RSV F vaccine candidates. Respiratory syncytial virus (RSV) is a pervasive pathogen that causes severe lower respiratory tract infections, leading to~100,000 deaths globally each year and hundreds of millions of dollars in healthcare costs. However, despite its prevalence, there is no vaccine for RSV and the only available therapy is limited to high-risk infants, leaving the vast majority of people with no effective means of prevention or treatment. The RSV fusion (F) protein is a major target of neutralizing antibodies, including extremely potent antibodies that PLOS Pathogens | https://doi.recognize prefusion-specific epitopes. In this study, we determined the crystal structures of two neutralizing human antibodies bound to prefusion RSV F. Our results reveal that each antibody recognizes a different conformation of a neutralization-sensitive epitope, suggesting that this region is inherently flexible and may be important for RSV F function. These results should guide future vaccine-design efforts and help elucidate the mechanisms of RSV F triggering and fusion. Conformational flexibility of antigenic site Ø PLOS Pathogens | https://doi.
[A]: Alternative conformations of a major antigenic site on RSV F


[Q]: Herpes simplex virus (HSV) infections can be treated with direct acting antivirals like acyclovir and foscarnet, but long-term use can lead to drug resistance, which motivates research into broadly-acting antivirals that can provide a greater genetic barrier to resistance. Photodynamic inactivation (PDI) employs a photosensitizer, light, and oxygen to create a local burst of reactive oxygen species that inactivate microorganisms. The botanical plant extract Orthoquin TM is a powerful photosensitizer with antimicrobial properties. Here we report that Orthoquin also has antiviral properties. Photoactivated Orthoquin inhibited herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) infection of target cells in a dose-dependent manner across a broad range of sub-cytotoxic concentrations. HSV inactivation required direct contact between Orthoquin and the inoculum, whereas pre-treatment of target cells had no effect. Orthoquin did not cause appreciable damage to viral capsids or premature release of viral genomes, as measured by qPCR for the HSV-1 genome. By contrast, immunoblotting for HSV-1 antigens in purified virion preparations suggested that higher doses of Orthoquin had a physical impact on certain HSV-1 proteins that altered protein mobility or antigen detection. Orthoquin PDI also inhibited the non-enveloped adenovirus (AdV) in a dose-dependent manner, whereas Orthoquin-mediated inhibition of the enveloped vesicular stomatitis virus (VSV) was light-independent. Together, these findings suggest that the broad antiviral effects of Orthoquin-mediated PDI may stem from damage to viral attachment proteins. facilitate attachment and entry into host cells. While HSV-1 and HSV-2 are similar, they share onlỹ 55% nucleotide identity. Lytic HSV infection of a cell begins with initial attachment to negatively charged cell surface heparan sulfate and chondroitin sulfate glycosaminoglycans, followed by stable attachment of viral glycoproteins to cell surface receptors and fusion of the viral envelope to the plasma membrane or internal membranes [2] . Fusion of viral and host membranes enables delivery of the viral nucleocapsid and tegument proteins to the cytoplasm. After the HSV nucleocapsid arrives at the nucleus and delivers the viral genome, HSV genes are expressed in an ordered temporal cascade. Viral egress requires primary envelopment of the genome-containing capsid at the inner nuclear membrane, fusion with the outer nuclear membrane and final envelopment at the trans-Golgi network. Mature virions then exit through the cellular secretory system. All stages of the HSV replication cycle offer potential targets for direct-acting antiviral (DAA) therapy. However, DAAs can be undermined by the emergence of drug resistant mutant viruses. Anti-HSV DAAs acyclovir and foscarnet offer examples of the hazards of drug resistance. These drugs interrupt HSV genome replication by different mechanisms of action. Acyclovir is a nucleoside analogue prodrug that selectively targets HSV infected cells through the action of the HSV thymidine kinase (TK) enzyme, which efficiently phosphorylates acyclovir and facilitates incorporation into nascent viral DNA genomes by the HSV DNA polymerase enzyme; incorporation of acyclovir into viral DNA terminates genome replication [3] . By contrast, the pyrophosphate analogue foscarnet blocks viral genome replication by directly inhibiting HSV DNA polymerase activity [4] . Though resistance to acyclovir occurs at a low prevalence (≤1%) in immunocompetent patients [5], immunocompromised patients experience much higher rates (4-10%) [6] . Unsurprisingly, resistance to acyclovir, and its derivatives, and to foscarnet, has been mapped to mutations in the viral thymidine kinase and the DNA polymerase catalytic subunit, respectively [7] . Currently, Abreva (n-docosanol) is the only over-the-counter topical antiviral for herpes labialis. Abreva is incorporated into the cellular plasma membrane and prevents fusion steps essential for HSV-1 entry into epithelial cells [8] . However, it must be applied repeatedly throughout the day due to rapid plasma membrane turnover and the subsequent loss of n-docosanol [9] . This host-targeted antiviral mechanism prevents development of viral resistance, but Abreva is only approved for perioral lesions, so there is a still a gap in treatment for lesions in other areas of the body. Like Abreva, there is potential for more broadly-acting antiviral drugs that exploit the physical structure of the HSV virion and block early stages of infection, such as attachment and penetration. In this study, we explored the potential of the plant-derived photosensitizing agent Orthoquin TM to mediate photodynamic inactivation (PDI) [10] of virions. The clinical utility of Orthoquin PDI of oral biofilms is an area of active investigation and there is clear potential for wider range of clinical applications. The basis of PDI is the photodynamic effect, which has been exploited in photodynamic therapy (PDT) [11, 12] for treatment of cancers [13] and age-related macular degeneration [14] . In PDT, photosensitizer compounds when exposed to visible light react with oxygen to generate reactive oxygen species (ROS) that include singlet oxygen [15] . ROS damage proteins, nucleic acids and lipids, which can lead to cell death. Some of the most well-known photosensitizing molecules for PDT are based on a tetrapyrrolic core and are found in naturally occurring pigments, such as heme, chlorophyll, and bacteriochlorophyll [16] . The accepted phototoxic mechanism for these types of photosensitizers involves the formation of an excited triplet state upon light absorption that can participate in electron (Type 1) or energy (Type 2) transfer processes. Type 1 electron transfer reactions typically lead to the formation of radical species like superoxide or hydroxyl radicals, whereas Type 2 energy transfer produces cytotoxic singlet oxygen. It is possible for a photosensitizer to initiate both Type 1 and 2 photoprocesses simultaneously, depending on the specific chemistry of the photosensitizing agent and its environment [16] . Due to the high reactivities and short lifetimes of oxidizing molecules, it is expected that only viral structures in close proximity to activated photosensitizing compounds will be affected.
[A]:
Photodynamic Inactivation of Herpes Simplex Viruses