Search results for "Infectivity"
showing 10 items of 103 documents
Surface-exposed Amino Acid Residues of HPV16 L1 Protein Mediating Interaction with Cell Surface Heparan Sulfate
2007
Efficient infection of cells by human papillomaviruses (HPVs) and pseudovirions requires primary interaction with cell surface proteoglycans with apparent preference for species carrying heparan sulfate (HS) side chains. To identify residues contributing to virus/cell interaction, we performed point mutational analysis of the HPV16 major capsid protein, L1, targeting surface-exposed amino acid residues. Replacement of lysine residues 278, 356, or 361 for alanine reduced cell binding and infectivity of pseudovirions. Various combinations of these amino acid exchanges further decreased cell attachment and infectivity with residual infectivity of less than 5% for the triple mutant, suggesting …
Quantification and viability assays of Toxoplasma gondii in commercial "Serrano" ham samples using magnetic capture real-time qPCR and bioassay techn…
2014
"Serrano" ham is a typical pork product from the Mediterranean area, highly valued for its flavour. To make Serrano ham, pork undergoes a salting and a subsequent fermentation process known as curing. Certain pigs used for meat production are an important source of Toxoplasma gondii infection in humans. We have developed a method for quantifying and assaying the viability of the T. gondii present in commercial Serrano ham samples. A magnetic capture method for the isolation of T. gondii DNA and a qRT-PCR were used to estimate the T. gondii burden in 475 commercial samples of "Serrano" ham in two presentation formats: ham pieces and sliced ham. The infectivity capacity of T. gondii in positi…
Determinants essential for the transmissible gastroenteritis virus-receptor interaction reside within a domain of aminopeptidase-N that is distinct f…
1994
The swine-specific coronavirus transmissible gastroenteritis virus (TGEV) uses pig aminopeptidase-N (pAPN) as a cellular receptor. We showed that the human aminopeptidase-N (hAPN) cannot substitute for pAPN in this respect, although the two enzymes have 80% amino acid sequence identity. In order to map the TGEV binding site on pAPN, we constructed a series of APN cDNA chimeras between pAPN and hAPN and analyzed them for their capacity to confer infectivity. The region between residues 717 and 813 was found to be essential for infectivity. This region also contains the epitopes for three TGEV-blocking monoclonal antibodies directed against pAPN. These data support the view that the catalytic…
Effects of salinity and temperature on long-term survival of the eel pathogen Vibrio vulnificus biotype 2 (serovar E)
1999
ABSTRACT Vibrio vulnificus biotype 2 (serovar E) is a primary eel pathogen. In this study, we performed long-term survival experiments to investigate whether the aquatic ecosystem can be a reservoir for this bacterium. We have used microcosms containing water of different salinities (ranging from 0.3 to 3.8%) maintained at three temperatures (12, 25, and 30°C). Temperature and salinity significantly affected long-term survival: (i) the optimal salinity for survival was 1.5%; (ii) lower salinities reduced survival, although they were nonlethal; and (ii) the optimal temperature for survival was dependent on the salinity (25°C for microcosms at 0.3 and 0.5% and 12°C for microcosms at 1.5 to 3.…
The influence of adult worm age and definitive host on the transmission of Echinostoma caproni: egg hatchability and miracidial infectivity.
2012
AbstractWe analysed the influence of different ages of Echinostoma caproni adult worms reared in different definitive host-species on egg hatchability and miracidial infectivity. Eggs obtained from 2-, 4- and 6-week-old adult worms collected from rats, hamsters and mice, hatched miracidia that were used to infect laboratory-reared specimens of Biomphalaria glabrata. Highest egg hatchability was obtained with eggs derived from hamsters and mice. Egg hatchability did not seem to be affected by the age of E. caproni adult worms. Miracidial infectivity was not affected by the definitive host species. However, miracidial infectivity was affected by the age of adult worms when they developed in t…
Absolute Humidity Influences the Seasonal Persistence and Infectivity of Human Norovirus
2014
ABSTRACT Norovirus (NoV) is one of the main causative agents of acute gastroenteritis worldwide. In temperate climates, outbreaks peak during the winter season. The mechanism by which climatic factors influence the occurrence of NoV outbreaks is unknown. We hypothesized that humidity is linked to NoV seasonality. Human NoV is not cultivatable, so we used cultivatable murine norovirus (MNV) as a surrogate to study its persistence when exposed to various levels of relative humidity (RH) from low (10% RH) to saturated (100% RH) conditions at 9 and 25°C. In addition, we conducted similar experiments with virus-like particles (VLPs) from the predominant GII-4 norovirus and studied changes in bin…
Transmission, infectivity and survival of Diplostomum spathaceum cercariae
2003
The transmission dynamics of the cercariae of Diplostomum spathaceum were investigated under laboratory conditions using cercariae collected from naturally infected Lymnaea stagnalis. Cercariae were kept in a constant temperature of 20 °C and the survival and infectivity to naïve young rainbow trout recorded at 3-h intervals until few cercariae were alive. Mortality initially remained constant but increased rapidly after 20 h. While a model of constant mortality fitted the survival data, an age-dependent model provided a better fit and implied that cercariae tended to carry similar quantities of resources and once these were exhausted the cercariae died. Cercarial infectivity also showed an…
Evidence that water transmits Vibrio vulnificus biotype 2 infections to eels
1995
Vibrio vulnificus biotype 2 is classically considered an obligate eel pathogen. However, it has recently been associated with one human septicemic case. In this paper, the opportunistic behavior of this pathogen is discussed. The bacterium can survive alone in brackish water or attached to eel surfaces for at least 14 days. It is able to spread through water and infect healthy eels by using skin as a portal of entry. These results suggest that water and infected eels may act as reservoirs of infection. A capsule seems to be essential for waterborne infectivity, which would explain why cells recovered from naturally diseased eels give rise to pure cultures of opaque colonies. The spread of t…
Data from: Life-history adjustments to intestinal inflammation in a gut nematode
2017
Many parasitic nematodes establish chronic infections. This implies a finely tuned interaction with the host immune response in order to avoid infection clearance. While a number of immune interference mechanisms have been described in nematodes, how parasites adapt to the immune environment provided by their hosts remains largely unexplored. Here, we used the gastrointestinal nematode Heligmosomoides polygyrus to investigate the plasticity of life history traits and immunomodulatory mechanisms in response to intestinal inflammation. We adopted an experimental model of induced colitis and exposed worms to intestinal inflammation at two different developmental stages (larvae and adults). We …
Hepatitis A infections from food.
2020
Food contaminated by hepatitis A virus (HAV) is responsible of the 2–7% of all HAV outbreaks worldwide. This review provides a description of the HAV characteristics, its infectivity and epidemiological features. In addition, this review compiles existing original papers reporting HAV prevalence, viral titres in foodstuffs and the risk associated with food contamination. The purpose of this revision is to conduct a structured and systematic review of the published molecular procedures for HAV detection in food, including the assessment of its infectivity.