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Topic: Infectivity

In the News (Tue 29 Dec 09)

Northern Trust

Marvin Harrison

Peter Chernin

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Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	CDC - Bovine Spongiform Encephalopathy Infectivity in Greater Kudu (Tragelaphus strepsiceros)
		As TSE infectivity has been demonstrated previously by bioassay in tissues preserved in formalin and paraffin wax (13,17,18), tissue samples obtained opportunistically after routine postmortem examinations of three additional kudu (A664, A666, and A1221) were also tested for infectivity by using mouse bioassay.
		Nonetheless, infectivity has been found previously in salivary glands of mice after injection of infected tissues with a high titer of scrapie agent (32) and of mink injected with the transmissible mink encephalopathy agent (33).
		Infectivity in the ileum of cattle challenged orally with bovine spongiform encephalopathy.
	www.cdc.gov /ncidod/EID/vol10no6/03-0615.htm (3188 words)

	Do heterosexual infectivity rates underestimate the infectivity of vaginal secretions?
		My calculations show that (if the infectivity rate of 0.0009 is correct, then for 3105 males to contract HIV through heterosexual contact would man that therw would have to have been 3,450,000 cases during 1997 of males exposing themselves to HIV through heterosexulal contact.
		Also, the infectivity estimate you use represents the risk for a woman associated with a single act of unprotected vaginal intercourse with a known infected man. The corresponding estimate for female-to-male transmission is not available but is presumably somewhat lower.
		Infectivity probably varies with duration of infection, with a number of other factors related to infectiousness and susceptibility, and may even be different for different strains of the virus.
	hivinsite.ucsf.edu /insite?page=ask-01-01-18 (700 words)

	Peru Technologies. BIOCOMPATIBLE ELECTRIC CURRENT ATTENUATES HIV-I INFECTIVITY (Site not responding. Last check: 2007-10-10)
		The reduction of infectivity was dependent upon, the total electric charge (uA x min) passing through the chamber to which the virus was exposed.
		Using this index of HIV-1 infectivity, it was determined that exposing virus to direct electric current suppressed its capacity to induce the formation of syncytia.
		Although extrapolation of these data predicts that ablation of HIV infectivity may be possible, and additional preliminary data support this prediction, the expectation t hat some virions may still escape the electrical effect cannot be discounted.
	www.perutechnologies.com /lymanpaper.htm (3007 words)

	HIV infectivity: information from epidemiological studies of heterosexual transmission.
		Newly developed statistical methods which account for the incomplete nature of the exposure data from these studies are used to estimate the infectivity and associated estimation error, to investigate effects of behavioral risk factors and to assess evidence for heterogeneity of infectivity across partnerships.
		Infectivity estimates from other studies and biological data on HIV infectivity are also reviewed.
		Results: Estimates of the constant per-contact infectivity from the three studies are similar, ranging from 0.0009 to 0.002 with overlapping 95% confidence intervals.
	www.aegis.com /aidsline/1997/jan/M9716178.html (528 words)

	HIV infectivity by contraceptive method from a partner study in northern Thailand.
		Objective: To measure HIV male to female infectivity (probability of transmission per intercourse) associated with use of different contraceptive methods or pregnancy in an ongoing partner study in Chiang Mai, Thailand.
		Infectivity for the non-hormonal/no method exposures was.0023 plus or minus.0022; that for exposures among pregnant women was.0017 plus or minus.0033.
		However, the infectivity was slightly higher when male CD4 counts were less than 200 cells compared to when CD4 counts were greater than or equal to 200 cells (P=.77).
	www.aegis.com /aidsline/1997/jan/M9716179.html (582 words)

	Prions: dose experiments
		The infective dose of the greatest dilution that caused the animal to die (often after years of incubation), was defined as infective unit (IU) if the animal receiving the inoculum was the same species as that of the animal that was donating it.
		The finding of infectivity in the buffy coat of blood has led to fears that CJD may be transferred by blood transfusions, but there has been no report of this.
		Infectivity can be measured in two ways, namely endpoint titration and the incubation time assay, but patterns of infectivity vary depending on which method is used.
	www.umn.edu /eoh/hazards/hazardssite/prions/priondose.html (1801 words)

	Prion Disease January 2000 News Update
		Infectivity bioassays were conducted in healthy mice, and the brains of all assay animals dying during the course of the experiments were examined for the presence of proteinase-resistant protein.
		Assuming that levels of human plasma infectivity are as low as or lower than those in mice, a practical consequence is that larger plasma pools would be predicted to reduce the risk of CJD transmission.
		The much higher levels of infectivity in buffy coat than in plasma in endogenously infected pools of blood, as well as the similar distribution of infectivity in normal human blood that had been "spiked" with intact infectious brain cells, strongly suggests that the origin of blood infectivity is to be found in the WBC.
	www.mad-cow.org /00/jan00_news.html (6216 words)

	ARS \| Publication request: Infectivity of Microsporidia Spores Stored in Water at Environmental Temperature
		To determine how long waterborne spores of these species could survive in the environment, culture derived spores were stored in water at 10, 15, 20, 25 and 30 C and tested for infectivity at weekly and monthly intervals by inoculation into cultured mammalian cells.
		Infectivity was based on the ability of stored spores to infect cells and produce intracellular cluster of microsporidia detectable by gram-chromotrope staining and light microscopy.
		These findings indicate that spores of different species differ in their longevity and temperature tolerance but at temperatures from 10 C to 30 C all 3 have the potential to remain infectious in the environment long enough to become widely dispersed.
	www.ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=131296 (416 words)

	CBER Research Project: Effects of Leukofiltration on Cells Experimentally Infected with TSE Agents (Site not responding. Last check: 2007-10-10)
		Because the infectivity of blood in rodents with experimental TSE is largely cell-associated, several countries have adopted a precautionary policy to universally leukoreduce (ULR) their blood products in order to decrease the theoretical risk of transmitting TSE disease by blood.
		TSE infectivity is propagated in the spleen of the hamster, so we plan to demonstrate the efficacy of leukoreduction on decreasing TSE infectivity by spiking separated splenocytes into whole blood and then filtering, titrating infectivity in the spiked starting material, the filtrate and the retentate.
		TSE infectivity is propagated in the hamster spleen, which should be a rich source of infected leukocytes.
	www.fda.gov /cber/research/0501801.htm (900 words)

	Prion muscle infectivity found in mice (Site not responding. Last check: 2007-10-10)
		Initially they explain that they were themselves surprised to some degree that infectivity was found in the muscle of the mice that were infected with prions and it was felt necessary to find out how this got there and whether this would be of significance in BSE as a risk to humans.
		The arguments that the goat with the infectivity in its muscles was not tested properly is unacceptable in that even though an inefficient method was used the infection was still found: in fact we would have expected no infection to have been found.
		It would be reasonable to expect that the level of infectivity in bovine muscle could build up to a similar level to that found in the mice, but that would be late in the incubation period.
	www.priondata.org /data/A_muscle.html (3846 words)

	ARS \| Publication request: Effect of Low Viability on Infectivity of Beauveria Bassiana Conidia Towards Silverleaf ...
		Thus, when the spore survivorship was reduced by half, the infectivity of remaining spores was also reduced by the same amount.
		When conidia are the infective unit being tested in bioassays and field trials, researchers sometimes compensate for low viability in a fungal preparation by increasing the concentration so that they have the desired number of viable conidia.
		Using a dose response bioassay, we found the LC50 for the preparation with high viability to be 306 viable spores mm-2; whereas, the LC50 for the low viability preparations was nearly twice as high, at 589 and 593 viable spores mm-2, respectively.
	www.ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=102330 (488 words)

	Defra, UK - Animal health and welfare - BSE - Science & research - Transmission of BSE
		A bioassay is able to detect infectivity directly, rather than by relying on a correlation with the presence of modified PrP as detected by immunological or histological methods.
		The effectiveness of murine bioassay is clearly demonstrated by the success of the assay in detecting BSE infectivity by both intra-cerebral and by oral routes of exposure.
		Experiments to determine whether or not infectivity was present in the tissues of clinically affected cattle began in 1987 with the inoculation of mice with brain from field cases of cattle affected with BSE.
	www.defra.gov.uk /animalh/bse/science-research/transmis.html (1468 words)

	Follicular Dendritic Cells and the Persistence of HIV Infectivity: The Role of Antibodies and Fc{gamma} Receptors -- ...
		Follicular Dendritic Cells and the Persistence of HIV Infectivity: The Role of Antibodies and Fc{gamma} Receptors -- Smith-Franklin et al.
		Follicular Dendritic Cells and the Persistence of HIV Infectivity: The Role of Antibodies and Fc Receptors
		FDC-Ab interactions inhibited the spontaneous release of gp120 from the virion, and this correlated with increased HIV infectivity.
	www.jimmunol.org /cgi/content/full/168/5/2408 (5632 words)

	Inhibition of Endosomal/Lysosomal Degradation Increases the Infectivity of Human Immunodeficiency Virus -- Fredericksen ...
		The infectivity of virus stocks pretreated with DNase I to remove contaminating DNA was determined essentially as indicated in Fig.
		Amantadine and chloroquine increase the infectivity of HIV-1 in a dose-dependent manner.
		For purposes of comparison, the infectivity of the virus in the absence of chloroquine was arbitrarily designated as 1.
	jvi.asm.org /cgi/content/full/76/22/11440 (4915 words)

	12. Titrating Newcastle disease virus for infectivity
		The Infectivity Titre of a suspension of Newcastle disease virus is the number of infectious units of virus per unit volume, usually expressed per mL.
		Estimate the infectivity titre in the suspension by considering previous titrations and storage conditions.
		The end point of the titration is used to calculate the infectivity titre of the original suspension of virus.
	www.fao.org /DOCREP/005/AC802E/ac802e0f.htm (1441 words)

	Salmonid viral haemorrhagic septicaemia virus: fusion-related enhancement of virus infectivity by peptides derived from ... (Site not responding. Last check: 2007-10-10)
		Salmonid viral haemorrhagic septicaemia virus: fusion-related enhancement of virus infectivity by peptides derived from viral glycoprotein G or a combinatorial library -- Mas et al.
		VHSV infectivity after pre-incubation of VHSV with G pepscan peptides at pH 7·6 (a) or 5·6 (b) before adding them to cells, of cells with VHSV before adding the G pepscan peptides (c) or of cells with G pepscan peptides before adding VHSV (d).
		Pre-incubation of VHSV with p5 prevents the inhibition of VHSV infectivity by NH ions (a) and reduces the low-pH requirement for VHSV-induced cell–cell fusion (b).
	vir.sgmjournals.org /cgi/content/full/83/11/2671 (6415 words)

	Generation and Infectivity Titration of an Infectious Stock of Avian Hepatitis E Virus (HEV) in Chickens and ... (Site not responding. Last check: 2007-10-10)
		Generation and Infectivity Titration of an Infectious Stock of Avian Hepatitis E Virus (HEV) in Chickens and Cross-Species Infection of Turkeys with Avian HEV -- Sun et al.
		The infectivity titer of the infectious avian HEV
		Infectivity titration of a prototype strain of hepatitis E virus in cynomolgus monkeys.
	jcm.asm.org /cgi/content/full/42/6/2658 (3927 words)

	Variation in the Infectivity of Listeria monocytogenes Isolates following Intragastric Inoculation of Mice -- Barbour ...
		The infectivities of 66 Listeria monocytogenes isolates were assessed by intragastric inoculation of mice.
		infective isolates of serovar 4b (0 of 18) and 1/2a, 1/2b, and
		isolates or average infectivity across the serovar, was not demonstrated.
	iai.asm.org /cgi/content/full/69/7/4657 (1880 words)

	Pressure Combined with Heat Reduces Prion Infectivity in Processed Meats: National Institute of Neurological Disorders ...
		The combination of high temperature and very high pressure in the preparation of processed meats such as hot dogs and salami may effectively reduce the presence of infective prions while retaining the taste, texture, and look of these meats, according to a study in today’s Proceedings of the National Academy of Sciences (PNAS) Early Edition.
		Scientists have been looking for strategies to inactivate any possible infectivity in meats, and although processes such as autoclaving and exposure to strong alkali or bleach are known to kill prions, they cannot be used successfully in food preparation.
		The NINDS is a component of the National Institutes of Health in Bethesda, Maryland, part of the U.S. Department of Health and Human Services, and is the nation's primary supporter of biomedical research on the brain and nervous system.
	www.ninds.nih.gov /news_and_events/press_releases/pressrelease_prion_infectivity_050503.htm (591 words)

	Ask A Scientist - Prions
		However, such treatments were ineffective in reducing the infectivity of prions.
		Probably the most important piece of evidence indicating that prions are not viruses is that prion infectivity copurifies with the prion protein—that is, prion infectivity is always associated with the purification of the prion protein.
		Furthermore, the degree of infectivity is associated with the concentration of the prion protein.
	www.hhmi.org /cgi-bin/askascientist/highlight.pl?kw=&file=answers/immunology/ans_015.html (493 words)

	Impact of Sample Collection and Processing on the Infectivity of Cryptosporidium
		Routine studies on the infectivity of C. parvum oocysts in-vitro are now possible with the advent of the FDM-MPN cell culture methodology.
		From a public health standpoint, it has become increasingly important to not only discern the presence of oocysts in untreated and treated waters, but to identify whether these oocysts are infectious and could threaten public health.
		The objective of this project was to identify potential deleterious effects of select methods of water sample collection and processing on the viability and infectivity of C. parvum oocysts.
	www.iwaponline.com /wio/2004/11/wio200411AF90973F.htm (219 words)

	Infectivity of Chlamydia trachomatis Serovar LGV but Not E Is Dependent on Host Cell Heparan Sulfate -- Taraktchoglou ...
		Infectivity of Chlamydia trachomatis Serovar LGV but Not E Is Dependent on Host Cell Heparan Sulfate -- Taraktchoglou et al.
		Infectivity inhibition results with serovar E (a) and serovar LGV (b) at 37°C Comparison of C.
		Comparison of serovar E and LGV infectivity of CHO-K1, pgsA-745 and pgsD-677 cells at 37°C. pgsA-745 and pgsD-677 cells are defective CHO-K1 cell lines.
	iai.asm.org /cgi/content/full/69/2/968 (6580 words)

	Comparing Cell Culture and Mouse Assays for Measuring Infectivity of Cryptospordium
		The objective of this research was to compare in-vitro cell culture methods with a mouse assay for measuring infectivity of Cryptosporidium parvum oocysts.
		The specific objectives were to (1) compare the dose response and sensitivity of cell culture and mouse assays with multiple isolates; (2) compare infectivity methods with oocysts exposed to environmental water samples; (3) determine the reproducibility and variability of the methods; and (4) compare cell culture and animal assays for assessing ozone and UV disinfection.
		The water industry should adopt in-vitro cell culture as a routine method for measuring the infectivity of waterborne C. parvum and C. hominis oocysts.
	www.iwaponline.com /wio/2005/06/wio200506AF91027F.htm (235 words)

	Decrease in Cryptosporidium parvum Oocyst Infectivity In Vitro by Using the Membrane Filter Dissolution Method for ...
		Lowered rates of infectivity were also observed from the CAM-acetone treatments.
		Although both cell culture and mouse infectivity models are suitable indicators of C.
		An assay combining cell culture with reverse transcriptase PCR to detect and determine the infectivity of waterborne Cryptosporidium parvum.
	aem.asm.org /cgi/content/full/67/7/3309 (2641 words)

	Sodium Lauryl Sulfate Abrogates Human Immunodeficiency Virus Infectivity by Affecting Viral Attachment -- Bestman-Smith ...
		SLS inhibited the infectivity of virons pseudotyped with A-MLV
		Soluble CD4 blocks the infectivity of diverse strains of HIV and SIV for T cells and monocytes but not for brain and muscle cells.
		Aurothiolates inhibit HIV-1 infectivity by gold(I) ligand exchange with a component of the virion surface.
	aac.asm.org /cgi/content/full/45/8/2229 (5064 words)

	Chlorate: a reversible inhibitor of proteoglycan sulphation in Chlamydia trachomatis-infected cells -- Fadel and Eley ...
		in the infectivity of LGV serovars, and to a lesser extent of
		of the host-cell GAGs in the infectivity of LGV serovars, and
		Taraktchoglou, M., Pacey, A. A., Turnbull, J. and Eley, A. Infectivity of Chlamydia trachomatis serovar LGV but not E is dependent on host cell heparan sulfate.
	jmm.sgmjournals.org /cgi/content/full/53/2/93 (1598 words)

	Emerging Infectious Diseases: Yellow fever virus infectivity for Bolivian Aedes aegypti mosquitoes
		In 1997 to 1998, six cases of YF were reported among Santa Cruz residents, and some were regarded as urban YF cases (3); despite a population >1 million, low vaccine immunization cover age, and the presence of Ac.
		Based on these observations, researchers have suggested that sylvan strains of YFV circulating in Bolivia may not be infective for Bolivian Ae.
		This study examined that hypothesis and the infectivity of a Bolivian strain of YFV for Bolivian Ae.
	www.findarticles.com /p/articles/mi_m0GVK/is_9_10/ai_n6211042 (1229 words)

	UK Finds Mad Cow Disease Infectivity In Cow Tonsil
		(Reuters) - New research shows that infectivity for the deadly mad cow disease is carried in bovine tonsils after it failed to show up in tests on cattle tonsil tissue using mice, the Food Standards Agency (FSA) said.
		New tests, considered to be 100 times more sensitive than those using mice, involve injecting a range of tissues from infected cattle into disease-free cows to determine if they carry infectivity, the Agency said in a statement posted on its Web Site on Friday.
		Current anti-disease measures require all cow tonsils to be removed from meat intended for human consumption, but tonsil tissue can be found at the root of cow's tongues, which can enter the food chain.
	www.rense.com /general30/uks.htm (396 words)

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