Rate Of Virus Spread Research Articles

Public Preferences and Willingness to Pay for a COVID-19 Vaccine in Iran: A Discrete Choice Experiment.

Background and objectiveThe coronavirus disease 2019 (COVID-19) pandemic is a major international threat and vaccination is the most robust strategy to terminate this crisis. It is helpful for policymakers to be aware of community preferences about vaccines. The present study aims to investigate the public’s preferences and willingness to pay for the COVID-19 vaccine in Iran.MethodsThis research is a cross-sectional study performed using a discrete choice experiment for a sample of the public population of several provinces of Iran in 2021. The samples were divided into two groups: one group expressed their preferences regarding the vaccine’s attributes, and another group expressed their preferences regarding prioritizing individuals to get the vaccine. The discrete choice experiment design included five attributes including effectiveness, risk of severe complications, price, location of vaccine production, and duration of protection related to preferences for vaccine selection and six attributes including age, underlying diseases, employment in the healthcare sector, the rate of virus spread, the necessary job, and cost to the community related to preferences for prioritizing individuals to get the vaccine. A total of 715 individuals completed the questionnaire. The conditional logit regression model was used to analyze the discrete choice experiment data. Willingness to pay for each attribute was also calculated.ResultsThe willingness to pay for the COVID-19 vaccine with 90% (70%) efficacy, the risk of severe complications for 1 (5) person per one million people, imported (domestic) vaccine, and 24-month (12-month) duration of protection attributes was about US$71 (US$37). The preference for vaccination for respondents was enhanced by increasing the efficacy and the duration of vaccine protection and decreasing complications and costs. The likelihood of prioritizing individuals to get a vaccination was increased for a person with an underlying disease, employment in the healthcare sector, the necessary job for the community, the high potential for virus spread in the community, and the high cost of death to the community. The age variable was not statistically significant for prioritizing individuals to get the vaccine.ConclusionsIn the setting of the COVID-19 vaccination program, the public’s preferences identified in this study should be considered. The obtained results provide useful information for policymakers to identify individual and social values for an appropriate vaccination strategy.Supplementary InformationThe online version contains supplementary material available at 10.1007/s41669-022-00359-x.

Application of Continuous Non-Gaussian Mortality Models with Markov Switchings to Forecast Mortality Rates

The ongoing pandemic has resulted in the development of models dealing with the rate of virus spread and the modelling of mortality rates μx,t. A new method of modelling the mortality rates μx,t with different time intervals of higher and lower dispersion has been proposed. The modelling was based on the Milevski–Promislov class of stochastic mortality models with Markov switches, in which excitations are modelled by second-order polynomials of results from a linear non-Gaussian filter. In contrast to literature models where switches are deterministic, the Markov switches are proposed in this approach, which seems to be a new idea. The obtained results confirm that in the time intervals with a higher dispersion of μx,t, the proposed method approximates the empirical data more accurately than the commonly used the Lee–Carter model.

Prospects for finding means of non-specific prevention of COVID-19 infection

With the ongoing pandemic of the SARS-CoV-2 virus and the emergence of its new genovariants, along with the relevance of addressing the issue of vaccination of the population, the importance of non-specific prophylaxis, which is designed to reduce the viral load on the body and slow down the rate of virus spread, is increasing. The currently available research and experience in the use of antiseptic drugs or their combinations with the antimicrobial peptide lysozyme can be used for this purpose.Currently available research and experience in the use of antiseptic drugs or their combinations with the antimicrobial peptide lysozyme can be used for this purpose. Under conditions of lysozyme deficiency unhindered accumulation of non-hydrolyzed substrate, which is a constant source of autoantigens, is accompanied by immunity, metabolic and tissue homeostasis disorders. Analysis of a comparative study of different groups of antiseptics showed high virulicidal efficacy of cetylpyridinium chlorideCetylpyridinium chloride has an electrostatic effect on viral membrane lipids, causing their aggregation and dissolution, which leads to disruption of the integrity of the virus membrane, its interaction with mucosal epithelial cells and penetration into target cells, having a direct virulicide effect on SARS-CoV-2. An important factor of innate mucosal immunity is lysozyme, it has antiviral, antibacterial, antifungal and anti-inflammatory effects, normalizes microbiocenosis, restores immune system activity, increases mucosal barrier function. The combination of cetylpyridinium chloride and lysozyme hydrochloride has a dual antiviral effect, reducing the viral load on the body and enhancing the ability to control the spread of SARS-CoV-2 both from patients in the prodromal period of the disease or with its clinical manifestations, and from asymptomatic carriers with confirmed COVID-19 infection status.

Large Evolutionary Rate Heterogeneity among and within HIV-1 Subtypes and CRFs.

HIV-1 is a fast-evolving, genetically diverse virus presently classified into several groups and subtypes. The virus evolves rapidly because of an error-prone polymerase, high rates of recombination, and selection in response to the host immune system and clinical management of the infection. The rate of evolution is also influenced by the rate of virus spread in a population and nature of the outbreak, among other factors. HIV-1 evolution is thus driven by a range of complex genetic, social, and epidemiological factors that complicates disease management and prevention. Here, we quantify the evolutionary (substitution) rate heterogeneity among major HIV-1 subtypes and recombinants by analyzing the largest collection of HIV-1 genetic data spanning the widest possible geographical (100 countries) and temporal (1981–2019) spread. We show that HIV-1 substitution rates vary substantially, sometimes by several folds, both across the virus genome and between major subtypes and recombinants, but also within a subtype. Across subtypes, rates ranged 3.5-fold from 1.34 × 10−3 to 4.72 × 10−3 in env and 2.3-fold from 0.95 × 10−3 to 2.18 × 10−3 substitutions site−1 year−1 in pol. Within the subtype, 3-fold rate variation was observed in env in different human populations. It is possible that HIV-1 lineages in different parts of the world are operating under different selection pressures leading to substantial rate heterogeneity within and between subtypes. We further highlight how such rate heterogeneity can complicate HIV-1 phylodynamic studies, specifically, inferences on epidemiological linkage of transmission clusters based on genetic distance or phylogenetic data, and can mislead estimates about the timing of HIV-1 lineages.

Seasonal Variation and COVID-19 Pandemic in Nepal

The World Health Organization has declared the novel coronavirus (SARS-CoV-2) Covid-19 as a pandemic as it has spread globally. Understanding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) global dispersal pattern, it is important to know the environmental parameters within which the virus survives. There is adequate evidence in epidemiological and biological aspects to prove human beings are prone to viral pathogens such as Middle East respiratory syndrome coronavirus, respiratory syncytial virus, and influenza virus in cold weather. Apart from the influence of seasonality, other factors that might impact the rate of virus spread includes the effectiveness of infection control practices, individual behavior and immunity, and emergency preparedness levels of countries. This viewpoint highlights the potential influence of weather conditions, seasons, and non-climatological factors on the geographical spread of cases of COVID-19 across the globe.

The Relationship between Ambient Temperature and Positive Cases of COVID-19; A Case Study in Abarkouh and Qeshm Cities of Iran

Introduction: The prevalence of infectious diseases varies depending on the type of micro-organism involved. Viral diseases can spread rapidly among communities, due to the specific characteristics of the virus. Coronavirus disease 2019 (COVID 19) is a new member of the coronavirus family that has caused rapid epidemics and affected the health and economy of the countries. The aim of this study was to investigate the relationship between the ambient temperature and the positive cases of COVID 19. Materials and Methods: In the present research, the relationship between the number of positive cases of COVID 19 and the ambient temperature was investigated in Abarkouh and Qeshm cities during a 49-day period. The collected data were analyzed by SPSS 16 software using descriptive statistics and correlation coefficient tests. Results: The average ambient temperatures in the study period were 19.16 ± 3.45 and 25.79 ± 1.83 for Abarkouh and Qeshm cities, respectively. During this period, the positive cases in Abarkouh and Qeshm cities were 38 and 28 people, respectively. The results of correlation test revealed a negative correlation between the ambient temperature and the number of patients with COVID 19 (the correlation rates were -0.107 and -0.083 with p-values of 0.46 and 0.57 for Abarkouh and Qeshm, respectively). Conclusion: Our results revealed that increase of air temperature was negatively correlated with the number of positive cases of COVID 19. It can be concluded that atmospheric temperature affects the virus outbreak. So, the rate of virus spread is expected to be reduced.

Spreading Rate of Virus on Energy of Dominating Intuitionistic Fuzzy Graph

Dominating intuitionistic fuzzy graph is defined. The energy of such graph is discussed. Also spreading rate of virus on energy of dominating intuitionistic fuzzy graph is analyzed. These concepts are illustrated with example.

Bound of energy with real and complex roots of an intuitionistic fuzzy directed graph

We analyse the spreading rate of virus in terms of energy of an intuitionistic fuzzy graph by taking the website http://www.pantechsolutions.net/ of the web navigation of customers. Also, we derive the lower and the upper bounds for the energy of an intuitionistic fuzzy graph. Finally, we end up with the output results by taking the four periods of the given website.

Full-length infectious clone of an Iranian isolate of chicken anemia virus.

An Iranian field strain of chicken anemia virus (CAV), designated IR CAV, was isolated in the Marek's disease virus-transformed lymphoblastoid cell line MDCC-MSB1 (MSB1) culture for the first time. The full-length CAV DNA of this strain was cloned in the bacterial plasmid pTZ57R/T to create the molecular clone pTZ-CAV. The nucleotide and deduced amino acid sequences of viral proteins of IR CAV were compared with those of representative CAV sequences including reference and commercial vaccine strains. IR CAV was not related to vaccine strains and also found to have glutamine at positions 139 and 144 confirming previous studies in which such mutations were associated with a slow rate of virus spread in cell culture. pTZ-CAV was digested with PstI to release IR CAV DNA and then transfected into MSB1 cell by electroporation. The transfected cells showed cytopathic effect similar to virion-initiated infection. One-day old specific pathogen-free chicks were inoculated with the regenerated virus, which had been obtained from transfected MSB1 cells, and compared with the chicks inoculated with IR CAV. Gross lesions in the birds inoculated with the regenerated virus illustrated the infectious nature of the regenerated virus from the cloned IR CAV DNA.

Spreading Rate of Virus on Energy of Laplacian Intuitionistic Fuzzy Graph

Laplacian intuitionistic fuzzy graph is defined. Energy of such graph is discussed. In [8] the authors conjectured that the inequality holds for all graphs. In this paper we are conjectured that the inequality does not hold for intuitionistic fuzzy directed graph. Also spreading rate of virus on energy of laplacian intuitionistic fuzzy graph is analyzed. AMS classification: 05C50; 15A18; 05C90; 05C72; 05C69

The Rate of Virus Spread in New Potato Cultivars in the North of Poland

The aim of this research was to assess the rate of increase in the level of tuber infection by PVY, PVM, and PLRV during three consecutive years of multiplication in the field for 17 new cultivars registered in Poland in 2009–2011 and for two cultivars not listed in the registry but popularly cultivated. The research was conducted in Bonin near Koszalin (north-western Poland) in 2010–2013. Tuber infection was assessed using DAS ELISA in a grow-out test in the winter-spring period. Among the 19 cultivars examined, eight had high resistance to PVY (above grade 8 on a scale of 1–9); during the 3-year research period, they were not infected. Also, cv. Gawin seemed more resistant than previously assumed. In contrast, cvs. Hermes and Sylvana, which were rated in the Netherlands as quite resistant, were clearly very susceptible (grade 3–4) in Polish conditions, as within 2 years 100% of tubers were infected with this virus. The greatest susceptibility to PVM was shown by cvs. Danuta and Stasia, 50% of which were infected, despite moderate exposure to the virus. Cultivars Zenia, Etiuda, Jubilat, and Viviana appeared very resistant to PVM as the number of infected tubers did not exceed 5%. PVM was not detected in the tubers of cvs. Bursztyn, Gustaw, and Legenda, which confirmed that these cultivars possess the Rm gene. Not all cultivars regarded susceptible (grade 3–4) to PLRV were infected. The virus was not found in tubers of cv. Bursztyn, while in cv. Hermes, assessed in the Netherlands as being quite resistant, almost 40% of tubers were infected.

Antipredator behaviour of Myzus persicae affects transmission efficiency of Broad bean wilt virus 1

Biological control has the potential to limit the population growth of arthropod vectors and consequently may be expected to reduce plant virus spread in a crop. However, reduction of vector abundance is not the only effect of biological control. Natural enemies might induce antipredator behaviour that affects feeding and dispersal of vectors, and therefore virus spread. Here we test the effect of two natural enemies on dispersal of the aphid vector Myzus persicae and transmission of Broad bean wilt virus 1 (BBWV-1), genus Fabavirus, which is non-persistently transmitted by aphids. One of the predators tested, the syrphid Sphaerophoria rueppellii, is considered to induce low disturbance in aphid colonies, whereas the other, the coccinellid Adalia bipunctata, is assumed to induce high disturbance. Natural enemies enhanced aphid dispersal, but not virus transmission as compared to the control treatment without predators. However, transmission efficiency of BBWV-1 was higher in the presence of coccinellid adults than with syrphids. The behavioural observations of predators and the reactions of aphids to their presence indicate that a stronger antipredator behaviour is induced by coccinellid adults than by syrphids. The different antipredator behaviour displayed by aphids towards coccinellid adults and syrphids might explain the differences found in the rate of virus spread in their presence.

The evolutionary rate dynamically tracks changes in HIV-1 epidemics: Application of a simple method for optimizing the evolutionary rate in phylogenetic trees with longitudinal data

Large-sequence datasets provide an opportunity to investigate the dynamics of pathogen epidemics. Thus, a fast method to estimate the evolutionary rate from large and numerous phylogenetic trees becomes necessary. Based on minimizing tip height variances, we optimize the root in a given phylogenetic tree to estimate the most homogenous evolutionary rate between samples from at least two different time points. Simulations showed that the method had no bias in the estimation of evolutionary rates and that it was robust to tree rooting and topological errors. We show that the evolutionary rates of HIV-1 subtype B and C epidemics have changed over time, with the rate of evolution inversely correlated to the rate of virus spread. For subtype B, the evolutionary rate slowed down and tracked the start of the HAART era in 1996. Subtype C in Ethiopia showed an increase in the evolutionary rate when the prevalence increase markedly slowed down in 1995. Thus, we show that the evolutionary rate of HIV-1 on the population level dynamically tracks epidemic events.

Cucumber mosaic virus infection of chickpea stands: temporal and spatial patterns of spread and yield‐limiting potential

Patterns of spread and yield losses were examined when migrant aphid vectors transmitted Cucumber mosaic virus (CMV) within chickpea (Cicer arietinum) plots. When numbers of chickpea plant infection foci were varied to provide initial infection incidences of 0·3–2%, rate of virus spread and its final incidence increased in proportion to initial virus incidence and pathogen progress curves reflected a polycyclic pattern of spread. Chickpea seed yields decreased by 44–45% when CMV incidence reached 61–74% at final assessment in plots with simulated 1–2% initial incidence. In chickpea plots with or without introduced lupin plant infection foci, cumulative spatial data for diseased plants were assessed using spatial analysis by distance indices (sadie). When CMV spread within a plot, infection was concentrated in large patch clusters and was consistent with comprehensive localized spread around primary infection foci. When introduced infection foci were absent, there was more diffuse spread with many isolated clusters. In individual plants that developed CMV symptoms at different growth stages, shoot and pod dry weight were reduced by 60–65% and 77–79% (early infection) and 44 and 66% (late infection), respectively. Seed yield losses were 78–80% (early) and 65–67% (late), and reduction in 50‐seed weight was 20–25% regardless of time of infection, so seed number was reduced more by early than late infection. Infection also reduced seed quality as, in addition to smaller seed size, seed coats were discoloured and malformed: the proportions of malformed seeds were 9–11% (early), 3–6% (late) and 0·5% (healthy).

Investigating the origin and spread of hepatitis C virus genotype 5a.

Epidemiological and phylogenetic studies of hepatitis C virus (HCV) have identified six major HCV genotypes and have attempted to characterize their origin and spread worldwide. Putative regions of endemic infection have been identified for all HCV genotypes except HCV genotype 5a. Although HCV genotype 5a was previously thought to be largely restricted to the northern part of South Africa, this study reports an unexpected cluster of the genotype in West Flanders Province in Belgium. To investigate the molecular epidemiology of this cluster and of HCV genotype 5a in general, a rigorous phylogenetic analysis of Belgian and South African HCV genotype 5a samples was performed. Remarkably, the Belgian and South African strains form two distinct clusters of similar diversity. We used a Bayesian coalescent method to estimate the rate of virus spread through time for HCV genotype 5a in both regions. Our results indicate that HCV genotype 5a strains have been spreading independently in Belgium and South Africa for more than 100 years, with a rate of spread characteristic of an epidemic genotype. These findings have major implications for tracing the origin of HCV genotype 5a. Here, we speculate about the possible origins of these clusters.

Identification of secret agent as the O-GlcNAc transferase that participates in Plum pox virus infection.

Serine and threonine of many nuclear and cytoplasmic proteins are posttranslationally modified with O-linked N-acetylglucosamine (O-GlcNAc). This modification is made by O-linked N-acetylglucosamine transferases (OGTs). Genetic and biochemical data have demonstrated the existence of two OGTs of Arabidopsis thaliana, SECRET AGENT (SEC) and SPINDLY (SPY), with at least partly overlapping functions, but there is little information on their target proteins. The N terminus of the capsid protein (CP) of Plum pox virus (PPV) isolated from Nicotiana clevelandii is O-GlcNAc modified. We show here that O-GlcNAc modification of PPV CP also takes place in other plant hosts, N. benthamiana and Arabidopsis. PPV was able to infect the Arabidopsis OGT mutants sec-1, sec-2, and spy-3, but at early times of the infection, both rate of virus spread and accumulation were reduced in sec-1 and sec-2 relative to spy-3 and wild-type plants. By matrix-assisted laser desorption ionization-time of flight mass spectrometry, we determined that a 39-residue tryptic peptide from the N terminus of CP of PPV purified from the spy-3 mutant, but not sec-1 or sec-2, was O-GlcNAc modified, suggesting that SEC but not SPY modifies the capsid. While our results indicate that O-GlcNAc modification of PPV CP by SEC is not essential for infection, they show that the modification has a role(s) in the process.

Temporal spread of wheat dwarf virus and mature plant resistance in winter wheat

Wheat dwarf is a potentially severe disease of winter wheat. The causal agent is wheat dwarf virus (WDV), a geminivirus transmitted by the leafhopper Psammotettix alienus. Field surveys of WDV incidence and vector occurrence were conducted for 4 years in winter wheat fields in central Sweden. The objective was to estimate the extent of primary spread of WDV in autumn, by adult leafhoppers migrating into the fields, and the secondary spread in the following early summer, by the progeny of the immigrants. We also related the rate of virus spread in early summer to the phenological development of the vector and the host plant. Furthermore, the development of mature plant resistance was assessed by inoculating winter wheat plants in various growth stages with infectious leafhoppers. Field survey data indicate that the rate of primary infections did not exceed 5%, and that infection rates increased to up to 50% during the summer. Infection rates ceased to increase as the crops reached the end of stem elongation, and virus transmission experiments showed that plants became resistant to infection at growth stage DC 31 (first node detectable).

Helper-dependent vs. Helper-independent CTL Responses in HIV Infection: Implications for Drug Therapy and Resistance

Clinical data from HIV-infected patients, as well as theoretical studies, suggest that CTL responses in the presence and absence of CD4 cell help are qualitatively different. In the presence of help, CTL responses are maintained despite very low antigenic loads and control the infection in the long term. In the absence of specific helper cell responses, CTL require high antigenic loads to be maintained, are short lived at low levels of antigen, and do not control the infection in the long term. This paper describes mathematical models analysing the dynamics of helper-dependent and helper-independent CTL in HIV infection with special focus on the dynamics during drug therapy in chronic infection. Theory suggests that a fast rate of virus spread results in high degrees of helper cell impairment which promotes the development of helper-independent CTL responses and compromised immunological control. In agreement with clinical findings, the model suggests that upon start of therapy, there is a transient increase in the level of CTL, followed by a decline to low levels once virus load has been significantly suppressed. According to the model, the presence of helper-independent CTL can promote the establishment of a helper-dependent memory response. Interestingly, this gives rise to the prediction that a relatively early stop of therapy, before the level of CTL has fallen below a threshold, can promote improved immunological control. Issues concerning the timing and duration of treatment are discussed. The CTL kinetics during drug therapy also provide new insights into the principles underlying the emergence of drug-resistant strains during the course of treatment.

Transmission of Pineapple Mealybug Wilt-Associated Virus by Two Species of Mealybug (Dysmicoccus spp.)

ABSTRACT Closterovirus-like particles associated with mealybug wilt of pineapple were acquired and transmitted by the pink pineapple mealybug, Dysmicoccus brevipes, and the gray pineapple mealybug, D. neobrevipes. Mealybugs acquired pineapple mealybug wilt-associated virus (PMWaV) from infected pineapple plants or detached leaves. The virus was detected in plants by tissue blot immunoassay and confirmed by immunosorbent electron microscopy. Plants exposed to mealybugs reared on PMWaV-free pineapple tissue remained uninfected. The presence of ants was correlated with an increased rate of virus spread when caged with D. brevipes. All stages of D. neobrevipes acquired PMWaV, although vector efficiency decreased significantly in older adult females. The probability of a single third-instar immature transmitting the virus was 0.04. Both species of mealybug acquired and transmitted PMWaV from infected pineapple material that had been clonally propagated for decades, and both species acquired PMWaV from sources previously infected with the virus by the other mealybug species.

Impact of Various Yield-Reducing Agents on Open-Field Sweet Peppers

Major damaging agents of open-field pepper crops in Spain are potato virus Y (PVY), the green peach aphid, Myzus persicae (Sulzer), and black nightshade, Solanum nigrum L. Yield loss of pepper affected by associations of these interacting agents was quantified in 1993 and 1994 under field conditions. Yield loss was greatest (82% both years) when all 3 yield-reducing factors were present. Aphid damage caused greater impact on total marketable yield than weed damage (56 versus 40% yield loss in 1993 and 65 versus 45% in 1994). Both agents combined (aphids and weeds) had a nonadditive effect on marketable yield loss. The number of marketable fruit per plant was the yield component most affected by aphid, weed, or virus damage in both years. Spread of PVY in pepper plots caused no additional yield losses over those produced by the other 2 damaging agents. In 1993, spread of PVY on pepper plots was higher in the presence of virus-infected nightshades than when infected peppers acted as the inoculum source. Therefore, S. nigrum may enhance aphid movement and increase the rate of virus spread.