No abstract

Aging has been implicated in the development of pulmonary fibrosis, which has seen a sharp increase in incidence in those older than 50 years. Recent studies demonstrate a role for the nucleotide-binding domain and leucine rich repeat containing family, pyrin domain containing 3 (NLRP3) inflammasome and its regulated cytokines in experimental lung fibrosis. In this study, we tested the hypothesis that age-related NLRP3 inflammasome activation is an important predisposing factor in the development of pulmonary fibrosis. Briefly, young and aged wild-type and NLRP3(-/-) mice were subjected to bleomycin-induced lung injury. Pulmonary fibrosis was determined by histology and hydroxyproline accumulation. Bone marrow and alveolar macrophages were isolated from these mice. NLRP3 inflammasome activation was assessed by co-immunoprecipitation experiments. IL-1β and IL-18 production was measured by ELISA. The current study demonstrated that aged wild-type mice developed more lung fibrosis and exhibited increased morbidity and mortality after bleomycin-induced lung injury, when compared with young mice. Bleomycin-exposed aged NLRP3(-/-) mice had reduced fibrosis compared with their wild-type age-matched counterparts. Bone marrow-derived and alveolar macrophages from aged mice displayed higher levels of NLRP3 inflammasome activation and caspase-1-dependent IL-1β and IL-18 production, which was associated with altered mitochondrial function and increased production of reactive oxygen species. Our study demonstrated that age-dependent increases in alveolar macrophage mitochondrial reactive oxygen species production and NLRP3 inflammasome activation contribute to the development of experimental fibrosis.

SARS-CoV-2 was first reported circulating in human populations in December 2019 and has since become a global pandemic. Recent history involving SARS-like coronavirus outbreaks have demonstrated the significant role of intermediate hosts in viral maintenance and transmission. Evidence of SARS-CoV-2 natural infection and experimental infections of a wide variety of animal species has been demonstrated, and in silico and in vitro studies have indicated that deer are susceptible to SARS-CoV-2 infection. White-tailed deer (WTD) are amongst the most abundant and geographically widespread wild ruminant species in the US. Recently, WTD fawns were shown to be susceptible to SARS-CoV-2. In the present study, we investigated the susceptibility and transmission of SARS-CoV-2 in adult WTD. In addition, we examined the competition of two SARS-CoV-2 isolates, representatives of the ancestral lineage A and the alpha variant of concern (VOC) B.1.1.7 through co-infection of WTD. Next-generation sequencing was used to determine the presence and transmission of each strain in the co-infected and contact sentinel animals. Our results demonstrate that adult WTD are highly susceptible to SARS-CoV-2 infection and can transmit the virus through direct contact as well as vertically from doe to fetus. Additionally, we determined that the alpha VOC B.1.1.7 isolate of SARS-CoV-2 outcompetes the ancestral lineage A isolate in WTD, as demonstrated by the genome of the virus shed from nasal and oral cavities from principal infected and contact animals, and from the genome of virus present in tissues of principal infected deer, fetuses and contact animals.

The rotavirus nonstructural protein NSP1 is the least conserved protein in the rotavirus genome, and its function in the replication cycle is not known. We employed NSP1 as bait in the yeast two-hybrid interaction trap to identify candidate cellular partners of NSP1 that may provide clues to its function. Interferon regulatory factor 3 (IRF-3) was identified as an NSP1 interactor. NSP1 synthesized in rotavirus-infected cells bound IRF-3 in a glutathione S-transferase pull-down assay, indicating that the interaction was not unique to the two-hybrid system. NSP1 of murine rotavirus strain EW also interacted with IRF-3. NSP1 deletion and point mutants were constructed to map domains important in the interaction between NSP1 and IRF-3. The data suggest that a binding domain resides in the C terminus of NSP1 and that the N-terminal conserved zinc finger is important but not sufficient to mediate binding to IRF-3. We predict that a role for NSP1 in rotavirus-infected cells is to inhibit activation of IRF-3 and diminish the cellular interferon response.Rotaviruses are the most important cause of severe, often life-threatening gastroenteritis in infants and children under 2 years of age (33). These viruses are ubiquitous in nature and are also responsible for a significant proportion of neonatal diarrheal illness in domestic animals, particularly in bovine and porcine species (18,40). Substantial research efforts have thus focused on understanding the correlates of a protective immune response to rotavirus infection and the molecular mechanisms of virus replication so that efficacious vaccines can be developed.The rotavirus segmented double-stranded RNA genome encodes six structural proteins (VP) and six nonstructural proteins (NSP) (reviewed in reference 17). The structural proteins VP1, VP2, VP3, VP4, VP6, and VP7 are well characterized in terms of their antigenic, structural, and biochemical properties. The functions of the rotavirus nonstructural proteins NSP1 to NSP6 are less well defined with regard to the roles that these proteins play in the rotavirus replication cycle. Intriguing functions have recently been described for some. NSP3 binds the 3Ј consensus sequence of viral mRNAs (37) and acts as a functional analog of poly(A) binding protein through its interaction with eIF4GI (36). NSP4 is both an intracellular glycoprotein receptor for maturating rotavirus particles that bud through the endoplasmic reticulum (3, 32) and a viral enterotoxin that induces diarrhea in mice in the absence of any other viral protein (5). Functions of the remaining nonstructural proteins, NSP1, NSP2, NSP5, and NSP6, have been proposed based predominately on biochemical properties and activities of recombinant proteins (reviewed in reference 17).NSP1 displays several interesting properties that warrant investigation. NSP1 has a calculated molecular weight of approximately 54,000 and is the least conserved protein encoded by the rotavirus genome when NSP1s of different strains are compared (23,34). The N terminus contains a conserved ...