Current topics in microbiology and immunology最新文献

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) swept across the world in the waning months of 2019 and emerged as the cause of the coronavirus disease 19 (COVID-19) pandemic in early 2020. The use of convalescent plasma (CP) for prior respiratory pandemics provided a strong biological rationale for the rapid deployment of COVID-19 convalescent plasma (CCP) in early 2020 when no validated treatments or prior immunity existed. CCP is an antiviral agent, with its activity against SARS-CoV-2 stemming from specific antibodies elicited by the virus. Early efforts to investigate the efficacy of CCP in randomized clinical trials (RCTs) that targeted hospitalized patients with COVID-19 did not demonstrate the overall efficacy of CCP despite signals of benefit in certain subgroups, such as those treated earlier in disease. In contrast, studies adhering to the principles of antibody therapy in their study design, choice of patient population, and product qualification, i.e., those that administered high levels of specific antibody during the viral phase of disease in immunocompromised or very early in immunocompetent individuals, demonstrated benefits. In this chapter, we leverage the knowledge gained from clinical studies of CCP for COVID-19 to propose a framework for future studies of CP for a new infectious disease. This framework includes obtaining high-quality CP and designing clinical studies that adhere to the principles of antibody therapy to generate a robust evidence base for using CP.

Blood transfusion capacity in low- and middle-income countries (LMICs), encompassing both the safety and adequacy of the blood supply, is limited. The challenges facing blood banks in LMICs include regulatory oversight, blood donor selection, collection procedures, laboratory testing, and post-transfusion surveillance. A high proportion of LMICs are unable to fully meet clinical demands for blood products, and many do not meet even the minimum threshold of collection (10 units per 1000 population). Suboptimal clinical transfusion practices, in large part due to a lack of training in transfusion medicine, contribute to blood wastage. During the COVID-19 pandemic, high- and LMICs alike experienced blood shortages, in large part due to quarantine and containment measures that impeded donor mobility. COVID-19 convalescent plasma (CCP) was particularly appealing for the treatment of patients with COVID-19 in LMICs, as it is a relatively inexpensive intervention and makes use of the existing blood collection infrastructure. Nonetheless, the challenges of using CCP in LMICs need to be contextualized among broad concerns surrounding blood safety and availability. Specifically, reliance on first time, family replacement and paid donors, coupled with deficient infectious disease testing and quality oversight, increase the risk of transfusion transmitted infections from CCP in LMICs. Furthermore, many LMICs are unable to meet general transfusion needs; therefore, CCP collection also risked exacerbation of pervasive blood shortages.

In contrast to therapy in oncology and immune-related diseases, where dozens of monoclonal antibodies (mAbs) have been introduced, often in transformative fashion, the use of mAbs for infectious diseases is generally underdeveloped, with fewer than a dozen mAbs currently licensed for the treatment of microbial diseases. This situation is paradoxical given that antibodies are major products of the immune system for protecting against infectious diseases. The underdevelopment of mAbs for infectious diseases has several causes including the availability of effective therapy against many microbial diseases, the fact that many pathogenic microbes are antigenically diverse and thus all strains are not covered by a single mAb, and the high expense of mAb therapies. Despite these hurdles the number of mAbs licensed for infectious disease indications is slowly increasing and there are numerous opportunities for the development of mAbs in the prevention and treatment of microbial diseases.

Fungi occupy many niches, are a major component of life, and contribute significantly to biodiversity. While fungi are rarely associated with human and animal diseases, they are often associated with diseases of plants as well as decay and nutrient cycling in the environment. Fungal diseases in agricultural crops can cause reductions in crop production and quality. In the context of human health, some fungi can also produce toxins that can accumulate in agricultural products, thereby affecting food safety and health. This chapter focuses on the complex interactions between fungi and agricultural crops in the context of human health, using fungi that infect and contaminate grain crops as examples.

The use of the serum or plasma of patients or animals who have recovered from an infectious disease, or had been immunized with a relevant antigen, to treat or prevent the same infection in others began in the late 1880s when French and German scientists uncovered, one step at a time, several of the elements of the immune system's response to infection. A key finding was that the damage caused by some bacteria depends upon their secreted toxins which can be neutralized by biologic agents. Antitoxins to diphtheria and tetanus began to be manufactured in large animals in France, Germany, and the US in the 1890s and were soon being used worldwide. The impact of diphtheria antitoxin on childhood mortality was profound. Shortly after the development of antitoxins, convalescent serum began to be used for its anti-bactericidal properties thus addressing serious infections caused by non-toxin-producing organisms. The effectiveness of antitoxins and antisera was demonstrated by examining mortality rates in hospitals before and after the introduction of antitoxins, by comparisons of treated and untreated patients, by comparing early and late treatment and dosage, by examining vital data mortality trends, and by several randomized and alternate assignment trials. Antitoxins continue to have a role in the rare cases of diphtheria and other conditions largely eradicated by immunization, but serum therapy nearly disappeared from the medical armamentarium with the development of antibiotics in the 1940s. Inasmuch as new human pathogens are now emerging with unprecedented regularity as seen in the recent COVID-19 pandemic, and because specific therapies are unlikely to be available for them, plasma-based antibody therapies are likely to again carve out a niche in infectious disease control.

Fungal infections occur in a wide variety of mammals including cats, dogs, and exotic small mammals. These infections are generally categorized as superficial/cutaneous, subcutaneous, and systemic. While most reported cases involve cats and dogs, fungal infections have also been documented in various exotic small mammal species. Although microbiological diagnostic approaches are similar across patient species, clinical signs and treatment strategies can vary significantly. Managing these infections in veterinary medicine presents unique challenges, particularly in exotic small mammals, due to species-specific differences in pathophysiology, treatment options, and husbandry considerations. In this chapter, we discuss (1) superficial/cutaneous, (2) subcutaneous, (3) systemic fungal infections in cats, dogs, and exotic small mammals, and (4) the challenges with managing these veterinary fungal infections.

Humans have changed ecosystems on Earth in a myriad of different ways including the input of lethal levels of toxic compounds in habitats forcing organisms to adapt or die. New environmental challenges select for different adaptive traits and species communities; however, in historically poorly characterised taxa and communities, such as the fungi, it is a challenge to know exactly what these changes are. In this chapter, we summarise our knowledge of fungi adapting to polluted environments by compiling a broad-stroke review. We find that most research has been framed in terms of remediation and biomonitoring. Remediation is mostly studied in soil fungi and biomonitoring in lichen and mycorrhizal communities. We expect that genomics advances and advances in detecting microscopic fungi via metabarcoding will open up possibilities for the study of adaptations and communities in such environments. We also reflect upon how polluted environments change the evolutionary and ecological context of these organisms.

The COVID-19 pandemic, resulting from the emergence of the novel coronavirus SARS-CoV-2, posed unprecedented challenges to global health systems as no proven therapy was available. Initially, COVID-19 convalescent plasma (CCP) from recovered COVID-19 patients showed promise as a therapeutic option. However, the efficacy of this approach was closely correlated with the neutralizing antibody titer in the administered plasma and thus effectiveness was not always guaranteed. In response, hyperimmune immunoglobulins (hIG) derived from CCP obtained by apheresis from recovered or vaccinated individuals emerged as a potential alternative. hIG were purified through stringent chromatographic processing from CCP units and displayed varying results in clinical trials, although it seems likely that they improved outcomes compared to placebo or CCP at day 28, particularly in unvaccinated patients. The variability in the effect of hIG likely stems from factors such as the timing of outcome assessment, the administered dose of hIG, the patients' immunological background, and the matching between the variant infecting patients and the neutralization ability of the immunoglobulin batch, which depended on the timing of the CCP collection. Despite logistical challenges and high production costs, hIG showcase advantages over CCP, offering versatility in administration routes and eliminating the need for blood matching, thus facilitating administration in the community, and allowing for variant-specific preparations. hIG appear to be of particular importance in the treatment of immunocompromised patients and patients with persistent COVID-19, although studies in these populations are lacking. Non-human alternatives, such as equine-derived hIG and recombinant hIG, may provide a solution to the logistical challenges of large-scale hIG preparation. Further study is needed to explore these avenues. Establishing the infrastructure for large-scale hIG production independent of plasma donations emerges as a strategic approach for future pandemics, justifying exploration and promotion by health authorities.

Monoclonal antibodies targeting the Spike protein of SARS-CoV-2 have been widely deployed in the ongoing COVID-19 pandemic. I review here the impact of those therapeutics in the early pandemic, ranging from structural classification to outcomes in clinical trials to in vitro and in vivo evidence of basal and treatment-emergent immune escape. Unfortunately, the Omicron variant of concern has completely reset all achievements so far in mAb therapy for COVID-19. Despite the intrinsic limitations of this strategy, future developments such as respiratory delivery of further engineered mAb cocktails could lead to improved outcomes.

Convalescent Plasma (CP) has been used prophylactically and therapeutically over the past century to address a variety of infectious threats. Two tenets of the use of CP were clear from prior experience in the setting of other infectious outbreaks: (1) best results are obtained when CP is given early in the course of the disease, and (2) plasma containing high-titer neutralizing capacity is necessary to achieve optimal results. The magnitude of the COVID-19 pandemic along with the initial lack of effective therapeutic alternatives, combined with the relative safety of the approach of administration of CP, led to the initiation of an expanded access program (EAP) that ultimately provided CP to tens of thousands of individuals. When the program was initiated, no high-throughput assay was available for the determination of antibody titers, so antibody positive units were administered without regard to titer. With foresight regarding the need to ultimately determine such titers, samples from the CP units administered were retained and titers were determined retrospectively. An automated live-virus neutralization assay was ultimately selected for this purpose based on an evaluation of its accuracy and precision. Ultimately, an analysis performed in 13,794 individuals from the EAP for which clinical outcomes were known following the administration of single units of COVID-19 CP between the period of April and August 2020 indicated that higher titer COVID-19 CP was associated with a modest reduction in absolute mortality. The benefit observed was confined to individuals who were not intubated, and there was a trend toward a greater reduction in mortality using the highest SARS-CoV-2 neutralizing antibody-containing CP units. This experience during the COVID-19 pandemic is instructive for the future. To facilitate the production of CP that is likely to be most effective, high-throughput assays to determine neutralizing antibody titers need to be developed and implemented early during an outbreak to facilitate the identification and early administration of high-titer units.