Virustenazität

[Sarcelle]

Avian Dis. 2007 Mar ;51 (1 Suppl):285-9 17494568
Persistence of H5 and H7 avian influenza viruses in water.
[My paper] Justin D Brown , David E Swayne , Robert J Cooper , Rachel E Burns , David E Stallknecht
Although fecal-oral transmission of avian influenza viruses (AIV) via contaminated water represents a recognized mechanism for transmission within wild waterfowl populations, little is known about viral persistence in this medium. In order to provide initial data on persistence of H5 and H7 AIVs in water, we evaluated eight wild-type low-pathogenicity H5 and H7 AIVs isolated from species representing the two major influenza reservoirs (Anseriformes and Charadriiformes). In addition, the persistence of two highly pathogenic avian influenza (HPAI) H5N1 viruses from Asia was examined to provide some insight into the potential for these viruses to be transmitted and maintained in the environments of wild bird populations. Viruses were tested at two temperatures (17 C and 28 C) and three salinity levels (0, 15, and 30 parts per thousand sea salt). The wild-type H5 and H7 AIV persistence data to date indicate the following: 1) that H5 and H7 AIVs can persist for extended periods of time in water, with a duration of infectivity comparable to AIVs of other subtypes; 2) that the persistence of H5 and H7 AIVs is inversely proportional to temperature and salinity of water; and 3) that a significant interaction exists between the effects of temperature and salinity on the persistence of AIV, with the effect of salinity more prominent at lower temperatures. Results from the two HPAI H5N1 viruses from Asia indicate that these viruses did not persist as long as the wild-type AIVs.

[Sarcelle]

Persistence of avian influenza viruses in water
Stallknecht DE, Shane SM, Kearney MT, Zwank PJ.
Avian Dis. 1990 Apr-Jun;34(2):406-11

Department of Epidemiology and Community Health, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803.

Persistence of five avian influenza viruses (AIVs) derived from four waterfowl species in Louisiana and representing five hemagglutinin and neuraminidase subtypes was determined in distilled water at 17 C and 28 C. Infectivity was determined over 60 days by microtiter endpoint titration. One AIV was tested over 91 days at 4 C. Linear regression models for these viruses predicted that an initial concentration of 1 x 10(6) TCID50/ml water could remain infective for up to 207 days at 17 C and up to 102 days at 28 C. Significant differences in slopes for AIV persistence models were detected between treatment temperatures and among viruses. Results suggest that these viruses are adapted to transmission on waterfowl wintering habitats. Results also suggest a potential risk associated with waterfowl and domestic poultry sharing a common water source.
http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Citation
MeSH Terms:

[Sarcelle]

Effects of pH, temperature, and salinity on persistence of avian influenza viruses in water.
Avian Dis. 1990 Apr-Jun;34(2):406-11
Stallknecht DE, Kearney MT, Shane SM, Zwank PJ.
Stallknecht DE, Kearney MT, Shane SM, Zwank PJ: Effects of pH, temperature, and salinity on persistence of avian influenza viruses in water. Avian Dis. 1990 Apr-Jun;34(2):406-11

Department of Epidemiology and Community Health, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803.

The combined effects of water temperature, salinity, and pH on persistence of avian influenza virus (AIV) were evaluated in a model distilled-water system using three isolates from ducks sampled in Cameron Parish, Louisiana. Variables were tested within the ranges normally associated with surface water. Differences were detected between temperature (17 C and 28 C), pH (6.2, 7.2, 8.2), and salinity (0 ppt and 20 ppt), with a strong interactive effect observed between pH and salinity. Estimated persistence of infectivity for 1 x 10(6) mean tissue-culture infective dose of A/mottled duck/LA/38M/87 (H6N2) was longest at 17 C/0 ppt/pH 8.2 (100 days) and shortest at 28 C/20 ppt/pH 8.2 (9 days). Differences in the response to these variables were apparent between viruses. The ability of AIV to persist in surface water was also evaluated using samples collected from varied waterfowl habitats in coastal Louisiana. Observations were consistent with the model system, with duration of infectivity decreasing with increased salinity and pH. This suggests that experimental results may have application to field conditions.
http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Abstract
PMID: 2142421 [PubMed - indexed for MEDLINE]

[Sarcelle]

Stability of infectious influenza A viruses to treatment at low pH and heating.
Arch Virol. 1985;85(1-2):1-11
Scholtissek C.

We have measured the infectivity of influenza A virus strains grown either in embryonated eggs or in chick embryo cells in culture after treatment at low pH. At pH values at which hemolysis occurs there was an irreversible loss of infectivity. The threshold pH, at which the infectivity was lost, depended on the hemagglutinin subtype of the virus strain. All H5 and H7 strains tested were extremely labile at low pH. In contrast, all H3 strains were relatively stable, independent of the species from which the viruses were isolated. With several H1 viruses the hemagglutination (HA) activity was irreversibly lost at intermediate pH values causing inactivation of infectivity. Strains with noncleaved hemagglutinins were much more stable. These observations might explain why duck influenza viruses can easily survive in lake water and wet faeces, and multiply in the intestinal tract, where trypsin is present. There are also significant differences in heat stability exhibited by influenza A strains. In contrast to pH stability this is not a specific trait of the hemagglutinin, since it can be influenced by reassortment. There is no correlation between the stability of infectivity at low pH and heat.
http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum
PMID: 4015405 [PubMed - indexed for MEDLINE]

[Sarcelle]

Comparison of biological and physical properties of human and animal A(H1N1) influenza viruses.
Res Virol. 1989 Sep-Oct;140(5):395-404
Fiszon B, Hannoun C, Garcia-Sastre A, Villar E, Cabezas JA.

Unite d'Ecologie Virale, Institut Pasteur, Paris.

The study of biological properties of influenza virus strains belonging to the same subtype A(H1N1) and closely antigenically related, but isolated from different animal species (man, pig and duck), demonstrated that avian strains were more resistant than those isolated from mammals to high temperature and low pH, as shown by titration of residual infectivity in cell cultures (MDCK) and by sialidase assay. The difference in behaviour could be correlated to biological adaptation of the virus to its host. Avian body temperature is 40 degrees C and influenza virus, in ducks, is enterotropic and therefore capable of passing through the low pH values in the upper digestive tract of the animal. These results do not contradict the hypothesis of a possible filiation between avian and mammalian orthomyxoviruses.
http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum
PMID: 2587848 [PubMed - indexed for MEDLINE]

[Sarcelle]

Stability of infectious influenza A viruses at low pH and at elevated temperature.
Vaccine. 1985 Sep;3(3 Suppl):215-8
Scholtissek C.

After treatment of different strains of influenza A at low pH, the threshold pH, at which the infectivity was lost, depended on the haemagglutinin (HA) subtype of the virus strain. Strains with noncleaved HA were much more stable when compared to strains with cleaved HA. These observations might explain why duck influenza viruses spread well by lake water, while highly pathogenic strains with cleaved HA do not. There were also significant differences in heat stability of infectivity among influenza A strains, which do not correlate with differences in stability at low pH.
http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum
PMID: 4060851 [PubMed - indexed for MEDLINE]

[Sarcelle]

Possible waterborne transmission and maintenance of influenza viruses in domestic ducks.
Appl Environ Microbiol. 1982 Jan;43(1):110-5
Markwell DD, Shortridge KF.
Full Text:: http://www.pubmedcentral.gov/picrend...9&blobtype=pdf

Two duck farms in Hong Kong were examined monthly for 1 year for the occurrence and persistence of influenza viruses within the duck communities. The predominant virus in one community was H3N2, a virus antigenically related to the pandemic Hong Kong strain. This virus was isolated monthly throughout the year from feces or pond water or both, indicating a cycle of waterborne transmission. Viruses of the same antigenic combination were isolated 1 and 2 years after the last sampling occasion, implying persistence in the community. Infection was asymptomatic. Maintenance of virus appeared to be dependent upon the continual introduction of ducklings susceptible to infection onto virus-contaminated water; the feces of ducks 70 to 80 days old were generally free of detectable virus despite the exposure of the ducks to virus in pond water. In the second community, in which ducklings were not introduced after the initial sampling, the prevailing viruses, H7N1 and H7N2, also present asymptomatically, ceased to be detected once the ducks were 70 to 80 days old. The normal practice of raising ducks of different ages on the same farm, wherein the water supplies are shared, as typified by the first community, appears to be instrumental in maintaining a large reservoir of influenza viruses in the duck population of southern China.
It would appear, then, that influenza viruses are a waterborne, intestinal infection of ducks.

There was no convincing evidence that pond water temperature, bacterial content, or the pH of duck feces had any significant effect on the occurrence of virus.

Markwell DD, Shortridge KF: Possible waterborne transmission and maintenance of influenza viruses in domestic ducks. Appl Environ Microbiol. 1982 Jan;43(1):110-5

[gsgs]

interessant.
Jetzt haette ich gerne eine Formel
T(ph,Salz,Temp.,serotype) der die Zeit angibt bis 50%
der Viren deaktiviert sind.
(ist das überhaupt logarithmisch ?)

Oder ein Computer-Programm, wo man die Werte eingibt
und welches dann die Zeit ausspuckt.

[AnnTye]

Hallo,

einige Postings hatten mit dem Thema nichts zu tun, deshalb habe ich sie in diesen neuen Thread verschoben:
Fremdsprachen im Forum (OT aus "Virustenazität")

Viele Grüsse Antje

[Sarcelle]

Suggested citation for this article: Rice EW, Adcock NJ, Sivaganesan M, Brown JD, Stallknecht
DE, Swayne DE. Chlorine inactivation of highly pathogenic avian influenza virus (H5N1).
Emerg Infect Dis. 2007 Oct; [Epub ahead of print]
Chlorine Inactivation of Highly Pathogenic
Avian Influenza Virus (H5N1)
Eugene W. Rice,* Noreen J. Adcock,* Mano Sivaganesan,* Justin D. Brown,†
David E. Stallknecht,† and David E. Swayne‡
*US Environmental Protection Agency, Cincinnati, Ohio, USA; †University of Georgia, Athens, Georgia, USA; and
‡US Department of Agriculture, Athens, Georgia, USA
To determine resistance of highly pathogenic avian influenza (H5N1) virus to chlorination, we exposed
allantoic fluid containing 2 virus strains to chlorinated buffer at pH 7 and 8, at 5°C. Free chlorine
concentrations typically used in drinking water treatment are sufficient to inactivate the virus by >3 orders
of magnitude.
Growing concerns about the public health threat posed by highly pathogenic avian
influenza (HPAI) subtype H5N1 has prompted interest in evaluating environmental control
measures for this virus. The World Health Organization has noted that more information is
needed on the effectiveness of inactivation of subtype H5N1 in water (1). Since 2002, HPAI
(H5N1) has been reportedly isolated from >50 different wild avian species, mainly aquatic birds
in the order Anseriformes (2). Experimentally infected waterfowl shed moderate to large
quantities of the virus in their feces and respiratory secretions (3,4). HPAI viruses can persist in
simulated water environments, although generally for shorter periods than low pathogenic avian
influenza viruses (5,6). Open bodies of water, including drinking water reservoirs, can become
contaminated by birds that are actively shedding virus or by waterfowl carcasses. Surface runoff
also represents a potential source of contamination for groundwater. In terms of avian health,
drinking water has been implicated in the transmission of avian influenza among domestic
poultry (6–

http://www.cdc.gov/eid/content/13/10...d=eid07_0323_x