Conditions affecting the timing and magnitude of Hendra virus shedding across pteropodid bat populations in Australia

SUMMARYUnderstanding infection dynamics in animal hosts is fundamental to managing spillover and emergence of zoonotic infections. Hendra virus is endemic in Australian pteropodid bat populations and can be lethal to horses and humans. However, we know little about the factors driving Hendra virus prevalence in resevoir bat populations, making spillover difficult to predict. We use Hendra virus prevalence data collected from 13 000 pooled bat urine samples across space and time to determine if pulses of prevalence are periodic and synchronized across sites. We also test whether site-specific precipitation and temperature affect the amplitude of the largest annual prevalence pulses. We found little evidence for a periodic signal in Hendra virus prevalence. Although the largest amplitude pulses tended to occur over winter, pulses could also occur in other seasons. We found that Hendra virus prevalence was weakly synchronized across sites over short distances, suggesting that prevalence is driven by local-scale effects. Finally, we found that drier conditions in previous seasons and the abundance of Pteropus alecto were positively correlated with the peak annual values of Hendra virus prevalence. Our results suggest that in addition to seasonal effects, bat density and local climatic conditions interact to drive Hendra virus infection dynamics.

Download Full-text

Ecological dynamics of emerging bat virus spillover

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2014.2124 ◽

2015 ◽

Vol 282 (1798) ◽

pp. 20142124 ◽

Cited By ~ 213

Author(s):

Raina K. Plowright ◽

Peggy Eby ◽

Peter J. Hudson ◽

Ina L. Smith ◽

David Westcott ◽

...

Keyword(s):

Land Use ◽

Ebola Virus ◽

Land Use Changes ◽

Nipah Virus ◽

Reservoir Host ◽

Hendra Virus ◽

Marburg Virus ◽

Virus Shedding ◽

Viral Shedding ◽

Reservoir Hosts

Viruses that originate in bats may be the most notorious emerging zoonoses that spill over from wildlife into domestic animals and humans. Understanding how these infections filter through ecological systems to cause disease in humans is of profound importance to public health. Transmission of viruses from bats to humans requires a hierarchy of enabling conditions that connect the distribution of reservoir hosts, viral infection within these hosts, and exposure and susceptibility of recipient hosts. For many emerging bat viruses, spillover also requires viral shedding from bats, and survival of the virus in the environment. Focusing on Hendra virus, but also addressing Nipah virus, Ebola virus, Marburg virus and coronaviruses, we delineate this cross-species spillover dynamic from the within-host processes that drive virus excretion to land-use changes that increase interaction among species. We describe how land-use changes may affect co-occurrence and contact between bats and recipient hosts. Two hypotheses may explain temporal and spatial pulses of virus shedding in bat populations: episodic shedding from persistently infected bats or transient epidemics that occur as virus is transmitted among bat populations. Management of livestock also may affect the probability of exposure and disease. Interventions to decrease the probability of virus spillover can be implemented at multiple levels from targeting the reservoir host to managing recipient host exposure and susceptibility.

Download Full-text

A Bayesian approach to estimate changes in condom use from limited human immunodeficiency virus prevalence data

Journal of the Royal Statistical Society Series C (Applied Statistics) ◽

10.1111/rssc.12116 ◽

2015 ◽

Vol 65 (2) ◽

pp. 237-257 ◽

Cited By ~ 1

Author(s):

J. Dureau ◽

K. Kalogeropoulos ◽

P. Vickerman ◽

M. Pickles ◽

M.‐C. Boily

Keyword(s):

Human Immunodeficiency Virus ◽

Condom Use ◽

Bayesian Approach ◽

Human Immunodeficiency Virus Prevalence ◽

Prevalence Data ◽

Virus Prevalence ◽

Immunodeficiency Virus

Download Full-text

SARS-CoV-2 Infection in One Cat and Three Dogs Living in COVID-19-Positive Households in Madrid, Spain

Frontiers in Veterinary Science ◽

10.3389/fvets.2021.779341 ◽

2021 ◽

Vol 8 ◽

Author(s):

Guadalupe Miró ◽

Javier Regidor-Cerrillo ◽

Rocio Checa ◽

Carlos Diezma-Díaz ◽

Ana Montoya ◽

...

Keyword(s):

Clinical Signs ◽

Nasal Discharge ◽

Virus Shedding ◽

Clinical Exam ◽

Reverse Transcription Pcr ◽

Infection Dynamics ◽

Variant Lineage ◽

Biochemical Profiles ◽

Alpha Variant ◽

Complete Blood Counts

In this study, we describe SARS-CoV-2 infection dynamics in one cat and three dogs from households with confirmed human cases of COVID-19 living in the Madrid Community (Spain) at the time of expansion (December 2020 through June 2021) of the alpha variant (lineage B.1.1.7). A thorough physical exam and nasopharyngeal, oropharyngeal, and rectal swabs were collected for real-time reverse-transcription PCR (RT-qPCR) SARS-CoV-2 testing on day 0 and in successive samplings on days 7, 14, 21, and 47 during monitoring. Blood was also drawn to determine complete blood counts, biochemical profiles, and serology of the IgG response against SARS-CoV-2. On day 0, the cat case 1 presented with dyspnea and fever associated with a mild bronchoalveolar pattern. The dog cases 2, 3, and 4 were healthy, but case 2 presented with coughing, dyspnea, and weakness, and case 4 exhibited coughing and bilateral nasal discharge 3 and 6 days before the clinical exam. Case 3 (from the same household as case 2) remained asymptomatic. SARS-CoV-2 detection by RT-qPCR showed that the cat case 1 and the dog case 2 exhibited the lowest cycle threshold (Ct) (Ct < 30) when they presented clinical signs. Viral detection failed in successive samplings. Serological analyses revealed a positive IgG response in cat case 1 and dog cases 3 and 4 shortly after or simultaneously to virus shedding. Dog case 2 was seronegative, but seroconverted 21 days after SARS-CoV-2 detection. SARS-CoV-2 genome sequencing was attempted, and genomes were classified as belonging to the B.1.1.7 lineage.

Download Full-text

Age-related susceptibility of ferrets to SARS-CoV-2 infection

Journal of Virology ◽

10.1128/jvi.01455-21 ◽

2021 ◽

Author(s):

Mathias Martins ◽

Maureen H.V. Fernandes ◽

Lok R. Joshi ◽

Diego G. Diel

Keyword(s):

Respiratory Tract ◽

Viral Replication ◽

Viral Entry ◽

Upper Respiratory Tract ◽

Infectious Dose ◽

Virus Shedding ◽

Age Related ◽

Infection Dynamics ◽

Upper Respiratory ◽

Effect Of Age

Susceptibility to SARS-CoV-2 and the outcome of COVID-19 have been linked to underlying health conditions and the age of affected individuals. Here we assessed the effect of age on SARS-CoV-2 infection using a ferret model. For this, young (6-month-old) and aged (18-to-39-month-old) ferrets were inoculated intranasally with various doses of SARS-CoV-2. By using infectious virus shedding in respiratory secretions and seroconversion, we estimated that the infectious dose of SARS-CoV-2 in aged animals is ∼32 plaque forming units (PFU) per animal while in young animals it was estimated to be ∼100 PFU. We showed that viral replication in the upper respiratory tract and shedding in respiratory secretions is enhanced in aged ferrets when compared to young animals. Similar to observations in humans, this was associated with higher transcription levels of two key viral entry factors - ACE2 and TMPRSS2 - in the upper respiratory tract of aged ferrets. Importance In humans, ACE2 and TMPRSS2 are expressed in various cells and tissues, and a differential expression have been described in young and old people, with a higher level of expressing cells being detected in the nasal brushing of older people when compared to young individuals. We described the same pattern occurring in ferrets and we demonstrated that age affects susceptibility of ferrets to SARS-CoV-2. Aged animals were more likely to get infected when exposed to lower infectious dose of the virus when compared to young animals and the viral replication in the URT and shedding is enhanced in aged ferrets. Together these results suggest that the higher infectivity and enhanced ability of SARS-CoV-2 to replicate in aged individuals is associated – at least in part – with transcription levels of ACE2 and TMPRSS2 at the sites of virus entry. The young and aged ferret model developed here may represent a great platform to assess age-related differences in SARS-CoV-2 infection dynamics and replication.

Download Full-text

Modelling the in vitro pre-infection dynamics of Colletotrichum spp. isolated from yellow passion fruit in function of environmental variables

10.1101/781963 ◽

2019 ◽

Author(s):

Karinna Vieira Chiacchio Velame ◽

Hermes Peixoto Santos Filho ◽

Adelise de Almeida Lima ◽

Carlos Augusto Dórea Bragança ◽

Francisco Ferraz Laranjeira

Keyword(s):

Environmental Variables ◽

Climatic Conditions ◽

Passion Fruit ◽

Yield Reduction ◽

Post Harvest ◽

Infection Dynamics ◽

Mycelia Growth ◽

Wetness Period ◽

Yellow Passion Fruit

AbstractBrazil is the largest world producer of yellow passion fruit, but the mean yield (14.3t.ha-1) is less than half the potential of the crop. Part of this difference can be explained by plant health problems, including anthracnose caused by Colletotrichum spp. In regions with favorable climatic conditions, anthracnose can be a factor of significant yield reduction, but these regions have not yet been zoned. The objective of this study was to model the pre-infection dynamics of the fungus. The influence of temperature and photoperiod was studied on mycelia growth, sporulation and conidia germination. Mathematical models were fitted to the results and the optima for the environmental variables were estimated. The maximum mycelia growth was estimated to occur at 26.5°C. Between 24.5°C and 28.5°C the fungus grew from 95% to 100% of the estimated maximum. Temperatures below 13°C or above 34°C were harmful to mycelia growth. Temperatures over 26°C were the most favorable to sporulation while below 13°C sporulation was only 5% of the maximum. Optimum germination occurred between 25°C and 29°C with the ideal wetness period between 11h and 13h. These results can be used as a basis for zoning the risk of anthracnose occurrence in passion fruit producing regions.Significance and Impact of the StudyMany diseases affect the yellow passion fruit crop, limiting its yield; among them anthracnose, caused by Colletotrichum spp. The disease occurs in both field (leaf and stem symptoms) and post-harvest (fruits) conditions. Understanding the role environmental conditions play in the biological cycle of such diseases is essential for developing management strategies. By modelling mycelial growth, spore production and spore germination of Colletotrichum spp. as affected by temperature, photoperiod and wetness period, it was possible to characterize the pathogen’s pre-infectional dynamics. The results should be used as a first approximation to estimate the risk of anthracnose occurrence in pre- or post-harvest.

Download Full-text

Avian influenza infection dynamics under variable climatic conditions, viral prevalence is rainfall driven in waterfowl from temperate, south-east Australia

Veterinary Research ◽

10.1186/s13567-016-0308-2 ◽

2016 ◽

Vol 47 (1) ◽

Cited By ~ 16

Author(s):

Marta Ferenczi ◽

Christa Beckmann ◽

Simone Warner ◽

Richard Loyn ◽

Kim O’Riley ◽

...

Keyword(s):

Avian Influenza ◽

Influenza Infection ◽

Climatic Conditions ◽

Infection Dynamics

Download Full-text

Membrane Fusion Tropism and Heterotypic Functional Activities of the Nipah Virus and Hendra Virus Envelope Glycoproteins

Journal of Virology ◽

10.1128/jvi.76.22.11186-11198.2002 ◽

2002 ◽

Vol 76 (22) ◽

pp. 11186-11198 ◽

Cited By ~ 104

Author(s):

Katharine N. Bossart ◽

Lin-Fa Wang ◽

Michael N. Flora ◽

Kaw Bing Chua ◽

Sai Kit Lam ◽

...

Keyword(s):

Membrane Fusion ◽

Measles Virus ◽

Nipah Virus ◽

Recombinant Vaccinia Virus ◽

Hendra Virus ◽

Envelope Glycoproteins ◽

Emerging Viruses ◽

Fusion Event ◽

Virus Envelope ◽

Zoonotic Infections

ABSTRACT Nipah virus (NiV) and Hendra virus (HeV) are novel paramyxoviruses from pigs and horses, respectively, that are responsible for fatal zoonotic infections of humans. The unique genetic and biological characteristics of these emerging agents has led to their classification as the prototypic members of a new genus within the Paramyxovirinae subfamily called Henipavirus. These viruses are most closely related to members of the genus Morbillivirus and infect cells through a pH-independent membrane fusion event mediated by the actions of their attachment (G) and fusion (F) glycoproteins. Understanding their cell biological features and exploring the functional characteristics of the NiV and HeV glycoproteins will help define important properties of these emerging viruses and may provide new insights into paramyxovirus membrane fusion mechanisms. Using a recombinant vaccinia virus system and a quantitative assay for fusion, we demonstrate NiV glycoprotein function and the same pattern of cellular tropism recently reported for HeV-mediated fusion, suggesting that NiV likely uses the same cellular receptor for infection. Fusion specificity was verified by inhibition with a specific antiserum or peptides derived from the α-helical heptads of NiV or HeV F. Like that of HeV, NiV-mediated fusion also requires both F and G. Finally, interactions between the glycoproteins of the paramyxoviruses have not been well defined, but here we show that the NiV and HeV glycoproteins are capable of highly efficient heterotypic functional activity with each other. However, no heterotypic activity was observed with envelope glycoproteins of the morbilliviruses Measles virus and Canine distemper virus.

Download Full-text

Conflicting Effects of Climate and Vector Behavior on the Spread of a Plant Pathogen

Phytobiomes Journal ◽

10.1094/pbiomes-01-17-0004-r ◽

2017 ◽

Vol 1 (1) ◽

pp. 46-53 ◽

Cited By ~ 13

Author(s):

Matthew P. Daugherty ◽

Adam R. Zeilinger ◽

Rodrigo P. P. Almeida

Keyword(s):

Symptom Onset ◽

Plant Pathogen ◽

Climatic Conditions ◽

Interactive Effects ◽

Disease Dynamics ◽

Disease Symptoms ◽

Vector Population ◽

Infection Dynamics ◽

Higher Temperature ◽

Vector Behavior

Local climatic conditions are important determinants of disease dynamics through effects on vector population performance or distribution. Yet, climate may also be epidemiologically significant due to effects on host−pathogen infection dynamics. We developed a model to explore interactive effects between climate-mediated acceleration in disease phenology (i.e., faster incubation or symptom onset) and vector preference based on host symptom status. Higher incubation rates favored pathogen outbreaks, but more rapid symptom onset may constrain spread if vectors avoid symptomatic hosts. Next, we tested whether warmer conditions favored greater spread of the plant pathogen, Xylella fastidiosa, by its leafhopper vector, Graphocephala atropunctata. Inoculated and healthy plants were reared in two temperature-controlled greenhouses. At six times postinoculation, a healthy and inoculated plant were exposed to noninfective vectors, after which pathogen spread was evaluated. Incubation rate and symptom onset in infected hosts was significantly accelerated at higher temperature. Although there was a tendency for greater pathogen spread at higher temperature, the effect depended on time since inoculation. In later introductions, after disease symptoms manifest, vectors were more likely to be found on healthy hosts. Vector avoidance of symptoms, particularly for hosts reared at higher temperature, constrained pathogen spread at later introductions. These results indicate that climate and vector behavior may mediate interactively pathogen spread. Further consideration of such epidemiological complexities is needed to predict adequately the consequences of climate change for disease dynamics.

Download Full-text