Biology subjects

Kelvin, A. A.

Publications and source records attributed to Kelvin, A. A..

8 recordsLinked to original sources

bioRxiv2025

MPXV Clade IIb virus infection in mice leads to prolonged viral replication, macrophage infiltration, and decreased spermatogenesis in the testes.

Mpox (formerly monkeypox) is caused by monkeypox virus (MPXV) and has prompted two recent global health emergencies. Clade IIb MPXV, a recently recognized subclade, has been associated with oral and genital lesions and transmission among men who have sex with men (MSM); however, mechanisms of genital pathogenesis and sexual transmission are not understood. We investigated several routes of MPXV Clade IIb virus infection (intranasal, oral, anal, and intraperitoneal) and found high and prolonged viral titres in the testes after IP inoculation still detectable at 21 days. The testes had significant changes to tissue architecture including loss of spermatogenesis, disorganization of spermatozoa, loss of Leydig cells, and breakdown of the seminiferous tubule membranes. Viral antigen positive cells were present in the interstitial spaces between the seminiferous tubules with macrophage infiltration also evident. This work provides insights into potential of sexual transmission for MPXV viruses as well as mechanisms of Mpox disease which may significantly impact long-term fertility or sex organ health of infected males. Author SummaryMpox (formerly monkeypox) is a painful disease similar to smallpox caused by the monkeypox virus (MPXV) which is an emerging/re-emerging virus. Recently the WHO has declared two global health emergencies due to human-to-human transmission of MPXV. Clade IIb MPXV is a newly recognized subclade that has been associated with genital lesions and sexual transmission/contact; however, how the virus causes disease in sex-organs or how it is passed from person-to-person is not understood. We investigated several routes of MPXV Clade IIb inoculation and found IP inoculation in male mice led to high and prolonged viral titres in testes. Additionally, the testes were significantly affected having loss of sperm and cellular organization. Evidence of inflammatory cell infiltration, specifically, macrophages, are suspected to be the cause of testes specific disease. This work provides insights into potential of sexual transmission for MPXV viruses as well as mechanisms of Mpox disease.

microbiology↗

bioRxiv2024

Bovine H5N1 influenza virus infection is transmitted by milk causing mortality in suckling neonates

The spread of H5N1 clade 2.3.4.4b in dairy herds raises concerns about zoonotic transmission due to its high viral load in milk, a key contact point between livestock and humans. H5N1 clade 2.3.4.4b exhibits tropism for the mammary gland, with milk from infected animals containing high levels of infectious virus, posing potential risks to offspring via breastfeeding. Using a lactating ferret model, we demonstrate that mammary gland infection with bovine H5N1 transmits the virus to suckling kits, resulting in neonatal mortality. Viral RNA levels increased in milk and remained high in mammary tissue, with infected kits exhibiting elevated viral RNA in the oral and nasal cavities and feces. Additionally, we detected the H5N1 receptor, 2,3 sialic acid, in ferret and human mammary tissue. These data demonstrate that H5N1 clade 2.3.4.4b infection in lactating dams leads to mastitis-related disease and transmits to suckling pups, resulting in mortality among neonates.

microbiology↗

bioRxiv2022

Pre-existing immunity to influenza viruses through infection and/or vaccination leads to viral mutational signatures associated with unique immune responses during a subsequent infection

Our biggest challenge to reducing the burden of seasonal influenza is the constant antigen drift of circulating influenza viruses which then evades the protection of pre-existing immunity. Continual viral infection and influenza vaccination creates a layered immune history in people, however, how host preimmunity interacts with an antigenically divergent virus exposure is poorly understood. Here we investigated the influence of host immune histories on influenza viral mutations. Immune backgrounds were devised in mice similar to what is experienced in people: naive; previously infected (A/FM/1/1947); previously vaccinated (Sanofi quadrivalent vaccine); and previously infected and then vaccinated. Mice were challenged with the heterologous H1N1 strain A/Mexico/4108/2009 to assess protection, viral mutation, and host responses in respect to each immune background by RNAseq. Viral sequences were analyzed for antigenic changes using DiscoTope 2.0 and Immune Epitope Database (IEDB) Analysis Resource NetMHCpan EL 4.1 servers. The mock infected-vaccinated group consistently had the greatest number of viral mutations seen across several viral proteins, HA, NA, NP, and PB1 which was associated with strong antiviral responses and moderate T cell and B cell responses. In contrast, the preimmune-vaccinated mice were not associated with variant emergence and the host profiles were characterized by minimal antiviral immunity but strong T cell, B cell, and NK cell responses. This work suggests that the infection and vaccination history of the host dictates the capacity for viral mutation at infection through immune pressure. These results are important for developing next generation vaccination strategies. ImportanceInfluenza is a continual public health problem. Due to constant virus circulation and vaccination efforts, people have complex influenza immune histories which may impact the outcome of future infections and vaccinations. How immune histories influence the emergence of new variants and the immune pressure stimulated at exposure is poorly understood. Our study addressed this knowledge gap by utilizing mice that are preimmune to influenza viruses and analyzing host responses as well as viral mutations associated with changes in antigenicity. Importantly, we found previous vaccination induced immune responses with moderate adaptive immunity and strong antiviral immunity which was associated with increased mutations in the influenza virus. Interestingly, animals that were previously infected with a heterologous virus and also vaccinated had robust adaptive responses with little to no antiviral induction which was associated with no emergence of viral variants. These results are important for the design of next generation influenza vaccines.

microbiology↗

bioRxiv2021

SARS-CoV-2 infection in the Syrian hamster model causes inflammation as well as type I interferon dysregulation in both respiratory and non-respiratory tissues including the heart and kidney

COVID-19 (coronavirus disease 2019) caused SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection is a disease affecting several organ systems. A model that captures all clinical symptoms of COVID-19 as well as long-haulers disease is needed. We investigated the host responses associated with infection in several major organ systems including the respiratory tract, the heart, and the kidneys after SARS-CoV-2 infection in Syrian hamsters. We found significant increases in inflammatory cytokines (IL-6, IL-1beta, and TNF) and type II interferons whereas type I interferons were inhibited. Examination of extrapulmonary tissue indicated inflammation in the kidney, liver, and heart which also lacked type I interferon upregulation. Histologically, the heart had evidence of mycarditis and microthrombi while the kidney had tubular inflammation. These results give insight into the multiorgan disease experienced by people with COVID-19 and possibly the prolonged disease in people with post-acute sequelae of SARS-CoV-2 (PASC).

microbiology↗

bioRxiv2021

Computational assessment of the spike protein antigenicity reveals diversity in B cell epitopes but stability in T cell epitopes across SARS-CoV-2 variants

Since its emergence into the human population at the end of 2019, SARS-CoV-2 has caused significant morbidity and mortality worldwide. Efforts to develop a protective vaccine against COVID-19 have yielded several vaccine platforms currently in distribution targeting the original SARS-CoV-2 spike protein sequence from the first cases of infection. In recent months, variants of SARS-CoV-2 have raised concerns that viral mutation may undermine vaccination efforts through viral escape of host immune memory acquired from infection or vaccination. We therefore used a computational approach to predict changes in spike protein antigenicity with respect to host B cell and CD8+ T cell immunity across six SARS-CoV-2 variants (D614G, B.1.1.7, B.1.351, P.1, B.1.429, and mink-related). Our epitope analysis using DiscoTope suggests possible changes in B cell epitopes in the S1 region of the spike protein across variants, in particular the B.1.1.7 and B.1.351 lineages, which may influence immunodominance. Additionally, we show that high-affinity MHC-I-binding peptides and glycosylation sites on the spike protein appear consistent between variants with the exception of an extra glycosylation site in the P.1 variant. Together, these analyses suggests T cell vaccine strategies have the most longevity before reformulation.

microbiology↗

bioRxiv2020

Glycomic analysis of host-response reveals high mannose as a key mediator of influenza severity

Influenza virus infections cause a wide variety of outcomes, from mild disease to 3-5 million cases of severe illness and ~290,000-645,000 deaths annually worldwide. The molecular mechanisms underlying these disparate outcomes are currently unknown. Glycosylation within the human host plays a critical role in influenza virus biology. However, the impact these modifications have on the severity of influenza disease has not been examined. Herein, we profile the glycomic host responses to influenza virus infection as a function of disease severity using a ferret model and our lectin microarray technology. We identify the glycan epitope high mannose as a marker of influenza virus-induced pathogenesis and severity of disease outcome. Induction of high mannose is dependent upon the unfolded protein response (UPR) pathway, a pathway previously shown to associate with lung damage and severity of influenza virus infection. Also, the mannan-binding lectin (MBL2), an innate immune lectin that negatively impacts influenza outcomes, recognizes influenza virus-infected cells in a high mannose dependent manner. Together, our data argue that the high mannose motif is an infection-associated molecular pattern on host cells that may guide immune responses leading to the concomitant damage associated with severity. SIGNIFICANCEInfluenza virus infection causes a range of outcomes from mild illness to death. The molecular mechanisms leading to these differential host responses are currently unknown. Herein, we identify the induction of high mannose, a glycan epitope, as a key mediator of severe disease outcome. We propose a mechanism in which activation of the unfolded protein response (UPR) upon influenza virus infection turns on expression of high mannose, which is then recognized by the innate immune lectin MBL2, activating the complement cascade and leading to subsequent inflammation. This work is the first to systematically study host glycomic changes in response to influenza virus infection, identifying high mannose as a key feature of differential host response.

microbiology↗

bioRxiv2020

Defective influenza A virus RNA products mediate MAVS-dependent upregulation of human leukocyte antigen class I proteins

Influenza A virus (IAV) increases presentation of class I human leukocyte antigen (HLA) proteins that limit antiviral responses mediated by natural killer (NK) cells, but molecular mechanisms have not yet been fully elucidated. We observed that infection with A/Fort Monmouth/1/1947 (H1N1) IAV significantly increased presentation of HLA-B, -C and -E on lung epithelial cells. Virus entry was not sufficient to induce HLA upregulation, because UV-inactivated virus had no effect. We found that HLA upregulation was elicited by aberrant internally-deleted viral RNAs (vRNAs) known as mini viral RNAs (mvRNAs) and defective interfering RNAs (DI RNAs), which bind to retinoic acid-inducible gene-I (RIG-I) and initiate mitochondrial antiviral signaling (MAVS) protein-dependent antiviral interferon (IFN) responses. Indeed, MAVS was required for HLA upregulation in response to IAV infection or ectopic mvRNA/DI RNA expression. The effect was partially due to paracrine signalling, as we observed that IAV infection or mvRNA/DI RNA-expression stimulated production of IFN-{beta} and IFN-{lambda}1, and conditioned media from these cells elicited a modest increase in HLA surface levels in naive epithelial cells. HLA upregulation in response to aberrant viral RNAs could be prevented by chemical blockade of IFN receptor signal transduction. While HLA upregulation would seem to be advantageous to the virus, it is kept in check by the viral non-structural 1 (NS1) protein; we determined that NS1 limits cell-intrinsic and paracrine mechanisms of HLA upregulation. Taken together, our findings indicate that aberrant IAV RNAs stimulate HLA presentation, which may aid viral evasion of innate immunity. IMPORTANCEHuman leukocyte antigens (HLA) are cell surface proteins that regulate innate and adaptive immune responses to viral infection by engaging with receptors on immune cells. Many viruses have evolved ways to evade host immune responses by modulating HLA expression and/or processing. Here, we provide evidence that aberrant RNA products of influenza virus genome replication can trigger RIG-I/MAVS-dependent remodeling of the cell surface, increasing surface presentation of HLA proteins known to inhibit the activation of an immune cell known as a natural killer (NK) cell. While this HLA upregulation would seem to be advantageous to the virus, it is kept in check by the viral non-structural 1 (NS1) protein, which limits RIG-I activation and interferon production by the infected cell.

microbiology↗

bioRxiv2019

Influenza preimmunity increases vaccination efficacy by influencing antibody longevity,neutralization activity, and epitope specificity

Influenza virus infections are a recurrent public health problem causing millions of hospitalizations each year despite vaccination efforts. The well-known yearly cycling of influenza viruses is the result of the reciprocal and coevolutionary relationship between the host and virus. Together, from the frequent infections and yearly vaccinations humans build a complex immune history over their lifetimes. Despite the prominence of immune history, vaccines are rarely evaluated in the imprinted (preimmune) host. We developed a ferret model for this purpose where ferrets were imprinted with a sublethal dose of the historical seasonal H1N1 strain A/USSR/90/1977 (USSR/77). A +60 day recovery period was given to build immune memory prior to vaccination with a split virion QIV vaccine. To evaluate protection, the ferrets were challenged with a 2009 H1N1 pandemic virus matching the vaccine antigens. The preimmune-vaccinated ferrets did not experience significant disease during challenge while the naive-vaccinated group were the most severe. Hemagglutination inhibition (HAI) assays showed that preimmune ferrets had a faster and longer antibody response post vaccination for all vaccine antigens compared to minimal HAI responses in the naive-vaccinated group. To investigate the immune mechanisms leading to disease protection in the preimmune ferrets, we performed microneutralization and isotype ELISA assays. Microneutralization suggested preimmune ferrets developed antibodies that were more functional for virus neutralization. Antibody isotype profiling indicated that virus specific antibodies in the preimmune-vaccinated ferrets was dominated by the IgG isotype suggesting B cell maturity and possible plasticity in a pre-existing B cell. Surprisingly, the naive-vaccinated ferrets developed a more severe disease with less virus neutralization suggesting improper immunological processing of vaccine antigens. Together, these results showed the preimmune host had greater responses to vaccination, and the predominant IgG virus specific antibodies suggested a flexible long-lived B cell response. These results are important and should be considered for vaccine design.\n\nAUTHOR SUMMARYThe influenza virus is a significant threat to human health and the economy despite large-scale vaccination efforts. The low effectiveness of the seasonal influenza vaccine is attributed to the frequently mutating virus enabling people to have several influenza virus infections throughout their lifetimes. As people are susceptible to multiple infections, they build a complex immune history. Despite this, vaccines are often not evaluated in animals with an immune history. Here we developed a ferret model that had previously been infected with a historical influenza virus to evaluate vaccine responses to current vaccines. Ferrets were infected with a sublethal does of a historical virus, A/USSR/90/1977, to develop a preimmune background. Preimmune ferrets were vaccinated with the Sanofi quadrivalent influenza vaccine and the antibody responses were investigated after vaccination. Our results showed that preimmune ferrets had a stronger antibody response following vaccination and the antibodies developed were older and better at neutralizing influenza virus at a virus challenge. Clinically, preimmune-vaccinated ferrets developed a milder disease during challenge compared to naive-vaccinated ferrets. This work indicates that the host responses to vaccination are dependent on the host background and that influenza vaccine development and evaluation should take host influenza background into account.

microbiology↗