Biology subjects

Lopez, C. B.

Publications and source records attributed to Lopez, C. B..

22 records · Page 2Linked to original sources

bioRxiv2022

Non-standard viral genome-derived RNA activates TLR3 and type I IFN signaling to induce cDC1-dependent CD8+ T-cell responses during vaccination in mice

There is a critical need to develop vaccine adjuvants that induce robust immune responses able to protect against intracellular pathogens, including viruses. Previously, we described the virus-derived adjuvant, defective viral genome-derived oligonucleotide (DDO), as a strong inducer of type 1 immune responses, including protective Th1 CD4+ T-cells and effector CD8+ T-cells in mice. Here we unravel the early innate response required for this type 1 immunity induction. Upon DDO subcutaneous injection, type 1 conventional dendritic cells (cDC1s) accumulate rapidly in the draining lymph node in a type I interferon (IFN)-dependent manner. cDC1 accumulation in the lymph node is required for antigen-specific CD8+ T-cell responses. Notably, in contrast to poly I:C, DDO administration resulted in type I IFN expression at the injection site, but not in the draining lymph node. Additionally, DDO induced an inflammatory cytokine profile distinct from that induced by poly I:C. Therefore, DDO represent a powerful new adjuvant to be used during vaccination against intracellular pathogens. IMPORTANCEThere is a paucity of vaccine adjuvants able to trigger effective and safe protective responses to many intracellular pathogens. Defining the minimal requirements to achieve type 1 immunity, which includes antigen specific CD8+ T cells capable of eliminating infected cells, is essential for the development of adjuvants that lead to optimal protective immune responses during vaccination against intracellular pathogens. We use a virus-derived immunostimulatory molecule, defective viral genome-derived oligonucleotide (DDO), to provide insights into how type 1 immune responses are triggered during vaccination using an inactivated influenza vaccine model. Understanding the mechanism of action of vaccine adjuvants not only aids in the advancement of vaccine development, but also in understanding specific immune pathways required for efficient induction of adaptive immune responses to infections.

immunology↗

bioRxiv2022

Accumulation of copy-back viral genomes during respiratory syncytial virus infection is preceded by diversification of the copy-back viral genome population followed by selection

RNA viruses generate non-standard viral genomes during their replication, including viral genomes of the copy-back (cbVG) type that cannot replicate in the absence of a standard virus. cbVGs play a crucial role in shaping virus infection outcomes due to their ability to interfere with virus replication and induce strong immune responses. However, despite their critical role during infection, the principles that drive the selection and evolution of cbVGs within a virus population are poorly understood. As cbVGs are dependent on the virus replication machinery to be generated and replicated, we hypothesized that host factors that affect virus replication exert selective pressure on cbVGs and drive their evolution within a virus population. To test this hypothesis, we used respiratory syncytial virus (RSV) as model and took an experimental evolution approach by serially passaging RSV in immune competent A549 control and immune deficient A549 STAT1 KO cells which allow higher levels of virus replication. As predicted, we observed that virus populations accumulated higher amounts of cbVGs in the more permissive A549 STAT1 KO cells over time but, unexpectedly, the predominant cbVG species after passages in the two conditions were different. While A549 STAT1 KO cells accumulated relatively short cbVGs, A549 control cells mainly contained cbVGs of much longer predicted size that have not been described previously. These long cbVGs were predominant at first in both cell lines in vitro and the predominant ones observed in samples from RSV infected patients. Although sustained high replication levels are associated with cbVG generation and accumulation, our data show that sustained high levels of virus replication are critical for cbVG population diversification, a process that preceded the generation of shorter cbVGs that selectively accumulated over time. Taken together, we show that selection and evolution of cbVGs within a virus population is shaped by how resistant or permissive a host is to RSV.

microbiology↗

bioRxiv2020

The Viral Polymerase Complex Mediates the Interaction of vRNPs with Recycling Endosomes During SeV Assembly

Paramyxoviruses are negative sense single-stranded RNA viruses that comprise many important human and animal pathogens, including human parainfluenza viruses. These viruses bud from the plasma membrane of infected cells after the viral ribonucleoprotein complex (vRNP) is transported from the cytoplasm to the cell membrane via Rab11a-marked recycling endosomes. The viral proteins that are critical for mediating this important initial step in viral assembly are unknown. Here we use the model paramyxovirus, murine parainfluenza virus 1, or Sendai virus (SeV), to investigate the roles of viral proteins in Rab11a-driven virion assembly. We previously reported that infection with SeV containing high levels of copy-back defective viral genomes (DVGs) generates heterogenous populations of cells. Cells enriched in full-length virus produce viral particles containing standard or defective viral genomes, while cells enriched in DVGs do not, despite high levels of defective viral genome replication. Here we take advantage of this heterogenous cell phenotype to identify proteins that mediate interaction of vRNPs with Rab11a. We examine the role of matrix protein and nucleoprotein and determine that they are not sufficient to drive interaction of vRNPs with recycling endosomes. Using a combination of mass spectrometry and comparative protein abundance and localization in DVG- and FL-high cells, we identify viral polymerase complex components L and, specifically, its cofactor C proteins as interactors with Rab11a. We find that accumulation of these proteins within the cell is the defining feature that differentiates cells that proceed to viral egress from cells which remain in replication phases. IMPORTANCEParamyxoviruses are a family of viruses that include a number of pathogens with significant burdens on human health. Particularly, human parainfluenza viruses are an important cause of pneumonia and bronchiolitis in children for which there are no vaccines or direct acting antivirals. These cytoplasmic replicating viruses bud from the plasma membrane and coopt cellular endosomal recycling pathways to traffic viral ribonucleoprotein complexes from the cytoplasm to the membrane of infected cells. The viral proteins required for viral engagement with the recycling endosome pathway are still not known. Here we use the model paramyxovirus Sendai virus, or murine parainfluenza virus 1, to investigate the role of viral proteins in this initial step of viral assembly. We find that viral polymerase components large protein L and accessory C proteins are necessary for engagement with recycling endosomes. These findings are important in identifying viral proteins as potential targets for development of antivirals.

microbiology↗

bioRxiv2018

Circadian control of lung inflammation in influenza infection

Influenza is a leading cause of respiratory mortality and morbidity. While inflammation is necessary for fighting infection, a fine balance of anti-viral defense and host tolerance is necessary for recovery. Circadian rhythms have been known to modulate inflammation. However, the importance of diurnal variability in the timing of influenza infection is not well understood. Here we demonstrate that endogenous rhythms influence the cellular response to infection in bronchoalveolar lavage (BAL), the pulmonary transcriptomic profile and lesional histology. This time dependent variability does not reflect alterations in viral replication. Rather, we found that better time-dependent outcomes were associated with a preponderance of NK and NKT cells and lower proportion of monocytes in the lung. Thus, host tolerance, rather than viral burden underlies the diurnal gating of influenza induced lung injury.\n\nSignificance statementOur work demonstrates the importance of circadian rhythms in influenza infection --a condition with significant public health implications. Our findings, which establish the role of the circadian rhythms in maintaining the balance between host tolerance pathways and anti-viral responses confers a new framework for evaluating the relevance of circadian influences on immunity.

immunology↗