Pandemics Throughout History Piret, Jocelyne; Boivin, Guy
Frontiers in microbiology,
01/2021, Letnik:
11
Journal Article
Recenzirano
Odprti dostop
The emergence and spread of infectious diseases with pandemic potential occurred regularly throughout history. Major pandemics and epidemics such as plague, cholera, flu, severe acute respiratory ...syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) have already afflicted humanity. The world is now facing the new coronavirus disease 2019 (COVID-19) pandemic. Many infectious diseases leading to pandemics are caused by zoonotic pathogens that were transmitted to humans due to increased contacts with animals through breeding, hunting and global trade activities. The understanding of the mechanisms of transmission of pathogens to humans allowed the establishment of methods to prevent and control infections. During centuries, implementation of public health measures such as isolation, quarantine and border control helped to contain the spread of infectious diseases and maintain the structure of the society. In the absence of pharmaceutical interventions, these containment methods have still been used nowadays to control COVID-19 pandemic. Global surveillance programs of water-borne pathogens, vector-borne diseases and zoonotic spillovers at the animal-human interface are of prime importance to rapidly detect the emergence of infectious threats. Novel technologies for rapid diagnostic testing, contact tracing, drug repurposing, biomarkers of disease severity as well as new platforms for the development and production of vaccines are needed for an effective response in case of pandemics.
Multiple respiratory viruses can concurrently or sequentially infect the respiratory tract and lead to virus‒virus interactions. Infection by a first virus could enhance or reduce infection and ...replication of a second virus, resulting in positive (additive or synergistic) or negative (antagonistic) interaction. The concept of viral interference has been demonstrated at the cellular, host, and population levels. The mechanisms involved in viral interference have been evaluated in differentiated airway epithelial cells and in animal models susceptible to the respiratory viruses of interest. A likely mechanism is the interferon response that could confer a temporary nonspecific immunity to the host. During the coronavirus disease pandemic, nonpharmacologic interventions have prevented the circulation of most respiratory viruses. Once the sanitary restrictions are lifted, circulation of seasonal respiratory viruses is expected to resume and will offer the opportunity to study their interactions, notably with severe acute respiratory syndrome coronavirus 2.
PURPOSE OF REVIEWAciclovir (ACV) is the first-line drug for the management of herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections. Long-term administration of ACV for the treatment ...of severe infections in immunocompromised patients can lead to the development of drug resistance. Furthermore, the emergence of isolates resistant to ACV is increasingly recognized in immunocompetent individuals with herpetic keratitis. This review describes the mechanisms involved in drug resistance for HSV and VZV, the laboratory diagnosis and management of patients with infections refractory to ACV therapy.
RECENT FINDINGSGenotypic testing is more frequently performed for the diagnosis of infections caused by drug-resistant HSV or VZV isolates. Molecular biology-based systems for the generation of recombinant viruses have been developed to link unknown mutations with their drug phenotypes. Fast and sensitive methods based on next-generation sequencing will improve the detection of heterogeneous viral populations of drug-resistant viruses and their temporal changes during antiviral therapy, which could allow better patient management. Novel promising compounds acting on targets that differ from the viral DNA polymerase are under clinical development.
SUMMARYAntiviral drug resistance monitoring for HSV and VZV is required for a rational use of antiviral therapy in high-risk populations.
The paradigm that females produce few costly eggs, whereas males produce an unlimited quantity of sperm holds true when matings are dispersed over time and males can replenish their sperm supply. In ...such a system, the best strategy for males is to mate with as many females as possible, as more is always better. However, in parasitoid species, mating often occurs at the emergence site and males may have to mate successively several females in a short period of time. This can lead to sperm depletion that can be temporary in synspermatogenic species whose males produce sperm throughout their adult life, or definitive in prospermatogenic species whose males emerge with their full sperm complement and do not produce more during their adult life. Both the spermatogeny index and the mating structure of a species will therefore influence the probability and intensity of sperm depletion in males. Sperm‐limited males can court and mate females even in prospermatogenic species. These males still gain some inclusive fitness by preventing competitor males to fully inseminate females, therefore increasing the representation of their daughters in the following generation. Females that mate with partially or completely sperm‐depleted males produce a constrained sex ratio that decreases their lifetime fitness. In species where sperm‐depleted males occur, female choosiness based on sperm supply is predicted, as the cost of mating sperm‐depleted males can be high. In addition, males are also expected to be choosy in prospermatogenic species as mating with sub‐optimal females can be costly when sperm is limited.
Neuraminidase inhibitors (NAIs) are first‐line agents for the treatment and prevention of influenza virus infections. As for other antivirals, the development of resistance to NAIs has become an ...important concern particularly in the case of A(H1N1) viruses and oseltamivir. The most frequently reported change conferring oseltamivir resistance in that viral context is the H275Y neuraminidase mutation (N1 numbering). Recent studies have shown that, in the presence of the appropriate permissive mutations, the H275Y variant can retain virulence and transmissibility in some viral backgrounds. Most oseltamivir‐resistant influenza A virus infections can be managed with the use of inhaled or intravenous zanamivir, another NAI. New NAI compounds and non‐neuraminidase agents as well as combination therapies are currently in clinical evaluation for the treatment for severe influenza infections.
The discovery of acyclovir (ACV), a nucleoside analogue, more than 30 years ago, represents a milestone in the management of HSV and VZV infections. The modest activity of ACV against CMV prompted ...the development of another nucleoside analogue, ganciclovir, for the management of systemic and organ-specific CMV diseases. Second-line agents such as the pyrophosphate analogue foscarnet and the nucleotide analogue cidofovir have been approved subsequently. In contrast to ACV and ganciclovir, the latter drugs do not require selective phosphorylation by viral protein kinases to be converted into their active forms. Since the introduction of these antivirals, the emergence of drug-resistant mutants has been constantly reported particularly in severely immunocompromised patients such as bone marrow and solid organ transplant recipients as well as HIV-infected individuals. In this manuscript, we discuss the characteristics of the antiviral agents currently approved for the management of HSV, VZV and CMV diseases. In recent years, the resistance of CMV to antiviral drugs has been extensively reviewed. The emergence of antiviral drug resistance is also observed with other members of the Herpesviridae family, namely HSV-1, HSV-2, VZV and HHV-6, which are the focus of this review. More specifically, we describe the laboratory methods for assessing drug susceptibilities, the frequency and clinical significance of drug-resistant infections and their management.
In 1947, Zika virus (ZIKV), a mosquito-borne flavivirus was identified in Uganda and subsequently spread to Asia and the Pacific regions. In 2015, it was introduced in Brazil causing an important ...social and sanitary alarm due to its increased virulence and rapid dissemination. Importantly, ZIKV infections have been associated with severe neurological complications such as Guillain-Barré syndrome and microcephaly in fetuses and newborns. Although enormous efforts were made by investigators in the development of effective countermeasures against ZIKV, there is still no approved specific antiviral drug for the treatment of ZIKV infections. Herein, we review several anti ZIKV candidates including drugs targeting both the virus (structural proteins and enzymes) and cellular elements.
Insect parasitoids cold storage. Display omitted
► This article focuses on cold storage of insect parasitoids. ► We reviewed genotypic-based plasticity in cold storage tolerance. ► We considered ...endogenous and exogenous factors affecting cold storage tolerance. ► We also examined the wealth of fitness traits affected by cold storage in parasitoids.
Storage at low temperature is a valuable method for increasing the shelf-life of natural enemies such as insect parasitoids. Cold storage is usually performed under sub-optimal temperatures, and therefore it is generally associated with major fitness costs. Tolerance to cold storage is a very plastic trait influenced by a wide range of endogenous (biotic) and exogenous (abiotic) factors experienced before, during, or after cold exposure. In fact, every hierarchical level from inter-species to inter-individuals shows a high plasticity in the response to cold exposure. Mortality represents the ultimate level of a range of sub-lethal perturbations accumulating during chilling. Even if individuals remain alive after cold storage, a reduction of several fitness-related traits may be observed directly, later in development or even in the next generation. The present review focuses on cold storage of insect parasitoids. We first consider the genotypic-based plasticity in cold storage tolerance and the complex network of endogenous and exogenous factors affecting the phenotypic plasticity in cold storage tolerance. We also summarize and examine the wealth of fitness-related traits affected by cold storage in parasitoids. This review provides a comprehensive list of documented factors that must be taken into account when designing cold storage protocols.
Antivirals play a critical role in the prevention and the management of influenza. One class of antivirals, neuraminidase inhibitors (NAIs), is effective against all human influenza viruses. ...Currently there are two NAI drugs which are licensed worldwide: oseltamivir (Tamiflu®) and zanamivir (Relenza®); and two drugs which have received recent approval in Japan: peramivir and laninamivir. Until recently, the prevalence of antiviral resistance has been relatively low. However, almost all seasonal H1N1 strains that circulated in 2008-09 were resistant to oseltamivir whereas about 1% of tested 2009 pandemic H1N1 viruses were found to be resistant to oseltamivir. To date, no studies have demonstrated widespread resistance to zanamivir. It seems likely that the literature on antiviral resistance associated with oseltamivir as well as zanamivir is now sufficiently comprehensive to warrant a systematic review.The primary objectives were to systematically review the literature to determine the incidence of resistance to oseltamivir, zanamivir, and peramivir in different population groups as well as assess the clinical consequences of antiviral resistance.
We searched MEDLINE and EMBASE without language restrictions in September 2010 to identify studies reporting incidence of resistance to oseltamivir, zanamivir, and peramivir. We used forest plots and meta-analysis of incidence of antiviral resistance associated with the three NAIs. Subgroup analyses were done across a number of population groups. Meta-analysis was also performed to evaluate associations between antiviral resistance and clinical complications and symptoms.
We identified 19 studies reporting incidence of antiviral resistance. Meta-analysis of 15 studies yielded a pooled incidence rate for oseltamivir resistance of 2.6% (95%CI 0.7% to 5.5%). The incidence rate for all zanamivir resistance studies was 0%. Only one study measured incidence of antiviral resistance among subjects given peramivir and was reported to be 0%. Subgroup analyses detected higher incidence rates among influenza A patients, especially for H1N1 subtype influenza. Considerable heterogeneity between studies precluded definite inferences about subgroup results for immunocompromised patients, in-patients, and children. A meta-analysis of 4 studies reporting association between oseltamivir-resistance and pneumonia yielded a statistically significant risk ratio of 4.2 (95% CI 1.3 to 13.1, p = 0.02). Oseltamivir-resistance was not statistically significantly associated with other clinical complications and symptoms.
Our results demonstrate that that a substantial number of patients may become oseltamivir-resistant as a result of oseltamivir use, and that oseltamivir resistance may be significantly associated with pneumonia. In contrast, zanamivir resistance has been rarely reported to date.
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