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Science (New York, N.Y.) Jul 2022The in vivo pathogenicity, transmissibility, and fitness of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron (B.1.1.529) variant are not well...
The in vivo pathogenicity, transmissibility, and fitness of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron (B.1.1.529) variant are not well understood. We compared these virological attributes of this new variant of concern (VOC) with those of the Delta (B.1.617.2) variant in a Syrian hamster model of COVID-19. Omicron-infected hamsters lost significantly less body weight and exhibited reduced clinical scores, respiratory tract viral burdens, cytokine and chemokine dysregulation, and lung damage than Delta-infected hamsters. Both variants were highly transmissible through contact transmission. In noncontact transmission studies Omicron demonstrated similar or higher transmissibility than Delta. Delta outcompeted Omicron without selection pressure, but this scenario changed once immune selection pressure with neutralizing antibodies-active against Delta but poorly active against Omicron-was introduced. Next-generation vaccines and antivirals effective against this new VOC are therefore urgently needed.
Topics: Animals; COVID-19; Disease Models, Animal; Mesocricetus; SARS-CoV-2; Virulence
PubMed: 35737809
DOI: 10.1126/science.abn8939 -
Journal of Infection in Developing... Apr 2014Visceral leishmaniasis (VL) is an important zoonosis caused by Leishmania infantum, which has in the domestic dog its principal vertebrate host. VL is usually... (Review)
Review
Visceral leishmaniasis (VL) is an important zoonosis caused by Leishmania infantum, which has in the domestic dog its principal vertebrate host. VL is usually transmitted by phlebotomine sand flies, however atypical routes of transmission have been described. In this review we discuss the the role of sexual and vertical transmissions, and their role in the maintenance of VL in canine populations.
Topics: Animals; Dogs; Humans; Infectious Disease Transmission, Vertical; Leishmania infantum; Leishmaniasis, Visceral; Mice; Semen; Sexually Transmitted Diseases
PubMed: 24727504
DOI: 10.3855/jidc.4108 -
Annals of Indian Academy of Neurology 2016Prion diseases or transmissible spongiform encephalopathies are fatal neurodegenerative diseases characterized by the aggregation and deposition of the misfolded prion... (Review)
Review
Prion diseases or transmissible spongiform encephalopathies are fatal neurodegenerative diseases characterized by the aggregation and deposition of the misfolded prion protein in the brain. α-synuclein (α-syn)-associated multiple system atrophy has been recently shown to be caused by a bona fide α-syn prion strain. Several other misfolded native proteins such as β-amyloid, tau and TDP-43 share some aspects of prions although none of them is shown to be transmissible in nature or in experimental animals. However, these prion-like "prionoids" are causal to a variety of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. The remarkable recent discovery of at least two new α-syn prion strains and their transmissibility in transgenic mice and in vitro cell models raises a distinct question as to whether some specific strain of other prionoids could have the capability of disease transmission in a manner similar to prions. In this overview, we briefly describe human and other mammalian prion diseases and comment on certain similarities between prion and prionoid and the possibility of prion-like transmissibility of some prionoid strains.
PubMed: 27293325
DOI: 10.4103/0972-2327.179979 -
Microbiology Spectrum Oct 2015Infectious diseases are still among the leading causes of death worldwide due to their persistence, emergence, and reemergence. As the recent Ebola virus disease and... (Review)
Review
Infectious diseases are still among the leading causes of death worldwide due to their persistence, emergence, and reemergence. As the recent Ebola virus disease and MERS-CoV outbreaks demonstrate, the modern epidemics and large-scale infectious outbreaks emerge and spread quickly. Air transportation is a major vehicle for the rapid spread and dissemination of communicable diseases, and there have been a number of reported outbreaks of serious airborne diseases aboard commercial flights including tuberculosis, severe acute respiratory syndrome, influenza, smallpox, and measles, to name a few. In 2014 alone, over 3.3 billion passengers (a number equivalent to 42% of the world population) and 50 million metric tons of cargo traveled by air from 41,000 airports and 50,000 routes worldwide, and significant growth is anticipated, with passenger numbers expected to reach 5.9 billion by 2030. Given the increasing numbers of travelers, the risk of infectious disease transmission during air travel is a significant concern, and this chapter focuses on the current knowledge about transmission of infectious diseases in the context of both transmissions within the aircraft passenger cabin and commercial aircraft serving as vehicles of worldwide infection spread.
Topics: Air Travel; Communicable Diseases; Disease Transmission, Infectious; Global Health; Humans; Risk Assessment
PubMed: 26542037
DOI: 10.1128/microbiolspec.IOL5-0009-2015 -
Transfusion Medicine and Hemotherapy :... Feb 2014Hepatitis E virus (HEV) has been recognized since 2004 as a transfusion-transmissible infectious agent, and recent epidemiological data suggest that it may pose a safety... (Review)
Review
Hepatitis E virus (HEV) has been recognized since 2004 as a transfusion-transmissible infectious agent, and recent epidemiological data suggest that it may pose a safety threat to the blood supply. It has recently become obvious that hepatitis E is endemic in industrialized countries, and that more infections are autochthonous than travel-associated. Epidemiological and phylogenetic analysis suggests that HEV infection has to be considered as a zoonosis and that viral transmission from animals (pigs, wild animals) occurs through food or direct contact. The seroprevalence and incidence of HEV in the general population and blood donors in European countries indicate an underestimated risk for transfusion transmissions. Recently reported cases of transfusion transmission of HEV infection, and detection of viremic, asymptomatic blood donors in nucleic acid amplification technique screening programs give an indication of the importance of this virus. Diagnostic assays for detection of anti-HEV antibodies, HEV antigens and RNA are discussed. Recent studies support the idea that active immunization can prevent hepatitis E, highlighting the need for vaccination programs. Here we review current knowledge of HEV and its epidemiology, blood transmission and prevention of this disease with emphasis on blood supply.
PubMed: 24659945
DOI: 10.1159/000357098 -
International Journal of Infectious... Mar 2024This study aimed to describe the lineage-specific transmissibility and epidemiological migration of Mycobacterium tuberculosis in China.
OBJECTIVES
This study aimed to describe the lineage-specific transmissibility and epidemiological migration of Mycobacterium tuberculosis in China.
METHODS
We curated a large set of whole-genome sequences from 3204 M. tuberculosis isolates, including thousands of newly sequenced genomes, and applied a series of metrics to compare the transmissibility of M. tuberculosis strains between lineages and sublineages. The countrywide transmission patterns of major lineages were explored.
RESULTS
We found that lineage 2 (L2) was the most prevalent lineage in China (85.7%), with the major sublineage 2.2.1 (80.9%), followed by lineage 4 (L4) (13.8%), which comprises major sublineages 4.2 (1.5%), 4.4 (6.2%) and 4.5 (5.8%). We showed evidence for frequent cross-regional spread and large cluster formation of L2.2.1 strains, whereas L4 strains were relatively geographically restricted in China. Next, we applied a series of genomic indices to evaluate M. tuberculosis strain transmissibility and uncovered higher transmissibility of L2.2.1 compared with the L2.2.2 and L4 sublineages. Phylogeographic analysis showed that southern, eastern, and northern China were highly connected regions for countrywide L2.2.1 strain spread.
CONCLUSIONS
The present study provides insights into the different transmission and migration patterns of the major M. tuberculosis lineages in China and highlights that transmissible L2.2.1 is a threat to tuberculosis control.
Topics: Humans; Mycobacterium tuberculosis; Phylogeny; Phylogeography; Genotype; Tuberculosis; China; Tuberculosis, Multidrug-Resistant
PubMed: 37863309
DOI: 10.1016/j.ijid.2023.10.015 -
Microbiology Spectrum Apr 2022The present study aimed to compare the susceptibility and infectivity between the Alpha and Delta variants of SARS-CoV-2 and to investigate characteristics of the index...
The present study aimed to compare the susceptibility and infectivity between the Alpha and Delta variants of SARS-CoV-2 and to investigate characteristics of the index case and the contact that may affect transmission. The risk of SARS-CoV-2 infection was compared between close contacts of COVID-19 cases with Alpha and Delta variants during June 2021 to August 2021. In index cases, Spike gene target failure (TaqPath) was used as a proxy of Alpha variant and the L452R mutation (TaqMan) for Delta variant. Cox regression models were used to estimate adjusted relative risks (RR). We compared close contacts of index cases with Alpha ( = 2139) and Delta variants ( = 5439). Delta variant was more transmissible overall (relative risk [RR] 1.32, 95% CI = 1.13 to 1.53), and in non-household contacts (RR 1.71, 95% CI = 1.35 to 2.16), but not in household contacts (RR 1.10, 95% CI = 0.91 to 1.34; < 0.001). Delta variant excess transmission was observed when the index cases were 12 to 39 years old (RR 1.51, 95% CI = 1.27 to 1.79) and the close contacts were 18 to 39 years old (RR 1.62, 95% CI = 1.29 to 2.03), but not among those younger or older than such ages. Differences in transmissibility between variants disappeared with vaccination of the index case (RR 0.68, 95% CI = 0.46 to 1.02), but not with vaccination of the close contact. This report shows that the Delta variant is more transmissible than Alpha variant mainly among young adults. Vaccination of the index cases reduced the excess transmission, which reinforces the recommendation of vaccination to reduce transmission of the Delta variant. The higher transmissibility of the Delta variant of SARS-CoV-2 in comparison with the Alpha variant has been reported. We compared the transmission of the Alpha and Delta variants by characteristics and COVID-19 vaccination status of index cases and their close contacts. Interestingly, the Delta variant showed increased transmissibility when the index case was an adolescent or young adult and when the close contact was a young adult; however, in index cases and close contacts of other age groups, transmission did not differ between variants. This may explain the increased proportion of young people who have been infected in the surges due to the Delta variant. The Delta variant was more transmissible than the Alpha variant when the index cases were unvaccinated against COVID-19, and their vaccination equaled the transmissibility of both variants, which suggests a higher impact of vaccination in controlling transmission of the Delta variant.
Topics: Adolescent; Adult; COVID-19; COVID-19 Vaccines; Child; Humans; SARS-CoV-2; Vaccination; Young Adult
PubMed: 35412379
DOI: 10.1128/spectrum.00008-22 -
Viruses Nov 2019The prion-like spreading and accumulation of specific protein aggregates appear to be central to the pathogenesis of many human diseases, including Alzheimer's and... (Review)
Review
The prion-like spreading and accumulation of specific protein aggregates appear to be central to the pathogenesis of many human diseases, including Alzheimer's and Parkinson's. Accumulating evidence indicates that inoculation of tissue extracts from diseased individuals into suitable experimental animals can in many cases induce the aggregation of the disease-associated protein, as well as related pathological lesions. These findings, together with the history of the prion field, have raised the questions about whether such disease-associated protein aggregates are transmissible between humans by casual or iatrogenic routes, and, if so, do they propagate enough in the new host to cause disease? These practical considerations are important because real, and perhaps even only imagined, risks of human-to-human transmission of diseases such as Alzheimer's and Parkinson's may force costly changes in clinical practice that, in turn, are likely to have unintended consequences. The prion field has taught us that a single protein, PrP, can aggregate into forms that can propagate exponentially in vitro, but range from being innocuous to deadly when injected into experimental animals in ways that depend strongly on factors such as conformational subtleties, routes of inoculation, and host responses. In assessing the hazards posed by various disease-associated, self-propagating protein aggregates, it is imperative to consider both their actual transmissibilities and the pathological consequences of their propagation, if any, in recipient hosts.
Topics: Alzheimer Disease; Amyloid; Animals; Humans; Membrane Proteins; Parkinson Disease; Prion Diseases; Prions; Protein Aggregates; Protein Folding; Scrapie; Synucleins; Virulence
PubMed: 31717531
DOI: 10.3390/v11111044 -
Current Opinion in Virology Aug 2023To cause pandemics, zoonotic respiratory viruses need to adapt to replication in and spread between humans, either via (indirect or direct) contact or through the air... (Review)
Review
To cause pandemics, zoonotic respiratory viruses need to adapt to replication in and spread between humans, either via (indirect or direct) contact or through the air via droplets and aerosols. To render influenza A viruses transmissible via air, three phenotypic viral properties must change, of which receptor-binding specificity and polymerase activity have been well studied. However, the third adaptive property, hemagglutinin (HA) acid stability, is less understood. Recent studies show that there may be a correlation between HA acid stability and virus survival in the air, suggesting that a premature conformational change of HA, triggered by low pH in the airways or droplets, may render viruses noninfectious before they can reach a new host. We here summarize available data from (animal) studies on the impact of HA acid stability on airborne transmission and hypothesize that the transmissibility of other respiratory viruses may also be impacted by an acidic environment in the airways.
Topics: Humans; Animals; Influenza A virus; Hemagglutinins; Hemagglutinin Glycoproteins, Influenza Virus; Respiratory System; Adaptation, Physiological; Influenza, Human; Orthomyxoviridae Infections
PubMed: 37307646
DOI: 10.1016/j.coviro.2023.101335 -
Journal of Infection in Developing... Nov 2009Dengue is the most important tropical mosquito-borne infectious disease caused by an arbovirus, the dengue virus. It should be noted that there are still other unusual... (Review)
Review
Dengue is the most important tropical mosquito-borne infectious disease caused by an arbovirus, the dengue virus. It should be noted that there are still other unusual modes of transmission of dengue infection. This paper summarizes those non vector-borne transmissions of dengue including vertical transmission, transfusion related transmission, transplantation related transmission, and needle-stick-related transmission.
Topics: Aedes; Animals; Blood Transfusion; Dengue; Dengue Virus; Humans; Infectious Disease Transmission, Vertical; Needlestick Injuries; Transplantation
PubMed: 20130380
DOI: 10.3855/jidc.145