Differential T-cell and Antibody Responses induced by mRNA versus adenoviral vectored COVID-19 vaccines in Patients with Immunodeficiencies

Background

Immunodeficient patients (IDPs) are at higher risk of contracting severe COVID-19 disease. Targeted vaccination strategies have been implemented to enhance vaccine-induced protection. In this population however, clinical effectiveness is variable and duration of protection unknown.

Objective

To understand the cellular and humoral immune responses to mRNA and adenoviral vectored COVID-19 vaccines in patients with immunodeficiency.

Methods

Immune responses to SARS-COV-2 spike were assessed after two doses of homologous ChAdOx1-nCoV-19 or BNT162b2 vaccines in 112 infection-naïve IDPs and 131 healthy health care workers (HCWs) as controls. Predictors of vaccine responsiveness were investigated.

Results

Immune responses to vaccination were low, and viral neutralisation by antibody not detected despite high titre binding responses in many IDPs. In those responding, the frequency of specific T-cell responses in IDPs was similar to controls whilst antibody responses were lower. Sustained vaccine specific differences were identified: T-cell responses were greater in ChAdOx1-nCoV-19 compared with BNT162b2 immunised IDPs and antibody binding and neutralisation was greater in all cohorts immunised with BNT162b2. The positive correlation between T-cell and antibody responses was weak and increased with subsequent vaccination.

Conclusion

Immunodeficient patients have impaired immune responses to mRNA and viral vector COVID-19 vaccines that appear influenced by vaccine formulation. Understanding the relative roles of T-cell and antibody mediated protection and potential of heterologous prime and boost immunization protocols is needed to optimise the vaccination approach in these high-risk groups.

Overview of Nonhuman Primate Models of SARS-CoV-2 Infection

COVID-19, the disease caused by the SARS-CoV-2 betacoronavirus, was declared a pandemic by the World Health Organization on March 11, 2020. Since then, SARS-CoV-2 has triggered a devastating global health and economic emergency. In response, a broad range of preclinical animal models have been used to identify effective therapies and vaccines. Current animal models do not express the full spectrum of human COVID-19 disease and pathology, with most exhibiting mild to moderate disease without mortality. NHPs are physiologically, genetically, and immunologically more closely related to humans than other animal species; thus, they provide a relevant model for SARS-CoV-2 investigations. This overview summarizes NHP models of SARS-CoV-2 and their role in vaccine and therapeutic development.

Severe Acute Respiratory Syndrome Coronavirus 2: Manifestations of Disease and Approaches to Treatment and Prevention in Humans

The coronavirus disease 2019 (COVID-19) pandemic was caused by a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This virus has challenged civilization and modern science in ways that few infectious diseases and natural disasters have previously, causing globally significant human morbidity and mortality and triggering economic downturns across financial markets that will be dealt with for generations. Despite this, the pandemic has also brought an opportunity for humanity to come together and participate in a shared scientific investigation. Clinically, SARS-CoV-2 is associated with lower mortality rates than other recently emerged coronaviruses, such as SARS-CoV and the Middle East respiratory syndrome coronavirus (MERS-CoV). However, SARS-CoV-2 exhibits efficient human-to-human spread, with transmission often occurring before symptom recognition; this feature averts containment strategies that had worked previ- ously for SARS-CoV and MERS-CoV. Severe COVID-19 disease is characterized by dysregulated inflammatory responses associated with pulmonary congestion and intravascular coagulopathy leading to pneumonia, vascular insults, and multiorgan disease. Approaches to treatment have combined supportive care with antivirals, such as remdesivir, with immunomodulatory medications, including corticosteroids and cytokine-blocking antibody therapies; these treatments have advanced rapidly through clinical trials. Innovative approaches to vaccine development have facilitated rapid advances in design, testing, and distribution. Much remains to be learned about SARS-CoV-2 and COVID-19, and further biomedical research is necessary, including comparative medicine studies in animal models. This overview of COVID-19 in humans will highlight important aspects of disease, relevant pathophysiology, underlying immunology, and therapeutics that have been developed to date.

Role of proteolytic enzymes in the COVID-19 infection and promising therapeutic approaches

In the Fall of 2019 a sudden and dramatic outbreak of a pulmonary disease (Coronavirus Disease COVID-19), due to a new Coronavirus strain (i.e., SARS-CoV-2), emerged in the continental Chinese area of Wuhan and quickly diffused throughout the world, causing up to now several hundreds of thousand deaths. As for common viral infections, the crucial event for the viral life cycle is the entry of genetic material inside the host cell, realized by the spike protein of the virus through its binding to host receptors and its activation by host proteases; this is followed by translation of the viral RNA into a polyprotein, exploiting the host cell machinery. The production of individual mature viral proteins is pivotal for replication and release of new virions. Several proteolytic enzymes either of the host and of the virus act in a concerted fashion to regulate and coordinate specific steps of the viral replication and assembly, such as (i) the entry of the virus, (ii) the maturation of the polyprotein and (iii) the assembly of the secreted virions for further diffusion. Therefore, proteases involved in these three steps are important targets, envisaging that molecules which interfere with their activity are promising therapeutic compounds. In this review, we will survey what is known up to now on the role of specific proteolytic enzymes in these three steps and of most promising compounds designed to impair this vicious cycle.

Pediatric Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): Clinical Presentation, Infectivity, and Immune Responses

OBJECTIVES

As schools plan for re-opening, understanding the potential role children play in the coronavirus infectious disease 2019 (COVID-19) pandemic and the factors that drive severe illness in children is critical.

STUDY DESIGN

Children ages 0-22 years with suspected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection presenting to urgent care clinics or being hospitalized for confirmed/suspected SARS-CoV-2 infection or multisystem inflammatory syndrome in children (MIS-C) at Massachusetts General Hospital were offered enrollment in the Massachusetts General Hospital Pediatric COVID-19 Biorepository. Enrolled children provided nasopharyngeal, oropharyngeal, and/or blood specimens. SARS-CoV-2 viral load, ACE2 RNA levels, and serology for SARS-CoV-2 were quantified.

RESULTS

A total of 192 children (mean age, 10.2 ± 7.0 years) were enrolled. Forty-nine children (26%) were diagnosed with acute SARS-CoV-2 infection; an additional 18 children (9%) met the criteria for MIS-C. Only 25 children (51%) with acute SARS-CoV-2 infection presented with fever; symptoms of SARS-CoV-2 infection, if present, were nonspecific. Nasopharyngeal viral load was highest in children in the first 2 days of symptoms, significantly higher than hospitalized adults with severe disease (P = .002). Age did not impact viral load, but younger children had lower angiotensin-converting enzyme 2 expression (P = .004). Immunoglobulin M (IgM) and Immunoglobulin G (IgG) to the receptor binding domain of the SARS-CoV-2 spike protein were increased in severe MIS-C (P < .001), with dysregulated humoral responses observed.

CONCLUSIONS

This study reveals that children may be a potential source of contagion in the SARS-CoV-2 pandemic despite having milder disease or a lack of symptoms; immune dysregulation is implicated in severe postinfectious MIS-C.

The underpinning biology relating to multiple sclerosis disease modifying treatments during the COVID-19 pandemic

BACKGROUND

SARS-CoV-2 viral infection causes COVID-19 that can result in severe acute respiratory distress syndrome (ARDS), which can cause significant mortality, leading to concern that immunosuppressive treatments for multiple sclerosis and other disorders have significant risks for both infection and ARDS.

OBJECTIVE

To examine the biology that potentially underpins immunity to the SARS-Cov-2 virus and the immunity-induced pathology related to COVID-19 and determine how this impinges on the use of current disease modifying treatments in multiple sclerosis.

OBSERVATIONS

Although information about the mechanisms of immunity are scant, it appears that monocyte/macrophages and then CD8 T cells are important in eliminating the SARS-CoV-2 virus. This may be facilitated via anti-viral antibody responses that may prevent re-infection. However, viral escape and infection of leucocytes to promote lymphopenia, apparent CD8 T cell exhaustion coupled with a cytokine storm and vascular pathology appears to contribute to the damage in ARDS.

IMPLICATIONS

In contrast to ablative haematopoietic stem cell therapy, most multiple-sclerosis-related disease modifying therapies do not particularly target the innate immune system and few have any major long-term impact on CD8 T cells to limit protection against COVID-19. In addition, few block the formation of immature B cells within lymphoid tissue that will provide antibody-mediated protection from (re)infection. However, adjustments to dosing schedules may help de-risk the chance of infection further and reduce the concerns of people with MS being treated during the COVID-19 pandemic.