China
Africa
Explore chapters and articles related to this topic
Inflection points
Published in J. Michael Ryan, COVID-19, 2020
Two essential points are related to the question, why now? First, human-caused disruptions to the ecosystem bring animal viruses into closer contact with humans. Second, human technology and behavior are spreading pathogens more widely and more quickly (Quammen 2012). In 2008, researchers at the Zoological Society of London reviewed 300 emerging infectious diseases and found that 60% were zoonotic and that nearly 72% of these zoonotic diseases were caused by pathogens with a wildlife origin. They concluded, “Zoonoses from wildlife represent the most significant growing threat to global health” (Quammen 2012, 44). Why some outbreaks of zoonotic diseases disappear without causing devastation and others go viral has to do with the virus’s transmissibility and virulence. Transmission is traveling from one host to another, and transmissibility is how that is achieved. For example, shedding the virus by coughing or sneezing makes the virus highly transmissible. Influenzas are well adapted for airborne transmission, which is why SARS and COVID-19 have had such high rates of transmission. Ebola and HIV, on the other hand, are transmitted through direct contact with bodily fluids; other viruses are transmitted by airborne vectors, mosquitos, or tick bites.
Edible Vaccine
Published in Hafiz Ansar Rasul Suleria, Megh R. Goyal, Masood Sadiq Butt, Phytochemicals from Medicinal Plants, 2019
Vivek K. Chaturvedi, Sushil K. Dubey, N. Tabassum, M.P. Singh
Edible vaccines (EVs) are milestones in medical biotechnology to provide protection against variety of diseases. They provide exciting possibilities for reducing the load of diseases especially in developing country, where storage and administration of vaccines are the major issues. These vaccines suppress many diseases like diarrhea, type-1 diabetes, multiple sclerosis, rheumatoid arthritis, autoimmune disorders, etc. The genes encoding bacterial and viral pathogenic antigens can be expressed in plants in a form in which they possess native immunogenic properties. Since it is a noninvasive method of immunization, therefore, the chances of infection are also decreased. There is always a risk associated with vaccine production from mammalian cell culture, which can get contaminated with animal viruses. While in case of EVs, it is not possible because plant viruses do not infect humans. Thus, they are harmless and safety is guaranteed. The oral administration of EVs provides “mucosal immunity” at various sites by secreting antibodies. The production is highly efficient, easily scaled up, and reduces cost of transportation and refrigeration.
Transcriptionally Regulatory Sequences of Phylogenetic Significance
Published in S. K. Dutta, DNA Systematics, 2019
Indeed animal viruses are transmitted only in selective tissues and often require specific interaction between their own transacting activator and cellular control elements. The human T cell leukemia virus genome carries an extra gene, X, whose product has been shown to act in a positive feedback manner, enhancing transcription of its own LTR and of other transcriptional units in T cells.262,263 Alternatively, LTR function may be suppressed by specific proteins in nonlymphoid cells.143 Genetic development may well involve a progressive reduction of the number of expressed genes.
Next generation live-attenuated influenza vaccine platforms
Published in Expert Review of Vaccines, 2022
Generally, influenza virus vaccine production takes around 4–5 months [44]. Due to antigenic evolution in influenza viruses, strategies to incorporate attenuation into the internal gene segments have been adopted. To create MDV, gene segments other than HA and NA are targeted for attenuation. To generate an antigenically matched vaccine for the seasonal outbreak, MDV is paired with HA and NA genes [45]. Many temperature-sensitive (ts) viruses were evaluated as vaccine candidates [46]. Due to a small number of mutations, phenotypic reversion occurred in vaccine candidates, and therefore, only the ts strategy did not succeed [47,48]. Another approach involved was the use of animal viruses through the intranasal route. This approach showed a low level of virus replication in humans due to animal virus inability to replicate efficiently [49]. Due to avian viruses’ adaptation to humans, they were considered naturally attenuated in humans. Unlike previous studies with ts variants, the virus would not undergo loss of attenuation or phenotype reversion [45].
Influenza vaccine programs for children in low- and middle-income countries: current status and way forward
Published in Expert Review of Vaccines, 2019
Justin R Ortiz, Kathleen M Neuzil
Influenza viruses circulate globally, affect people of all ages, and cause annual disease outbreaks. Influenza A viruses undergo frequent antigenic mutations (antigenic drift) that allow them to evade immune protection and to cause repeated infections in an individual over a lifetime [13]. Novel virus strains may emerge through genetic reassortment between different strains in a common host (antigenic shift) [14]. Further, non-human strains may directly infect and cause disease in humans [15]. Reassortment events or direct infection of humans by animal viruses have the potential to cause a pandemic if humans have little to no pre-existing immunity to the virus, if person-to-person transmission is sustained, and the infection causes clinical disease [16]. An influenza pandemic could be catastrophic for human health and have major effects on the functioning of societies and economies [13].
Safety of recombinant coagulation factors in treating hemophilia
Published in Expert Opinion on Drug Safety, 2019
Massimo Morfini, Carlo Antonio Paolo Rapisarda
The viral safety of recombinant factor VIII or IX concentrates has never been questioned, except for the first generation FVIII concentrates. The use of human albumin, produced from a large pool of donors, as a stabilizer in the final formulation of these concentrates was most likely responsible for the presence of TTV and Parvovirus B19 [1]. It is very well known that these viruses are resistant to virucidal methods, including solvent/detergent and heat treatment, and therefore they can contaminate human albumin even if it was subjected to pasteurization [2]. The viral contamination of the cell lines producing the recombinant drugs is theoretically possible, as it has been demonstrated by the detection of Vesivirus in the cell lines producing Cerezyme [3]. For these reasons, also the recombinant concentrates are subjected to inactivation or removal by nanofiltration of the hypothetical animal viruses contaminating the production cell lines. The transmission of animal viruses in patients treated with recombinant concentrates has never been detected. The problem of viral safety of clotting factor concentrates was the main topic of a review published in 2002 [4]. Nowadays this problem no longer worries treaters and patients with hemophilia because all rFVIII and rFIX concentrates are submitted to two or three viral inactivation steps (Tables 1 and 2).