Navigation Links
Neiker-Tecnalia makes progress in detection and prevention of infection by visna maedi virus
Date:1/19/2011

Researchers at Neiker-Tecnalia (the Basque Institute for Agricultural Research and Development) have undertaken a study on the epidemiology and diagnosis of infection by visna/maedi virus. This is a virus that affects sheep herds causing chronic interstitial pneumonia, mastitis and neurological disorders. The study confirmed that horizontal transmission (direct contact between infected animals) of the virus is the most likely path of infection, rather than vertical transmission (from infected suckling milk or colostrum). Since there is no current effective treatment against this virus, the study demonstrated the importance of control methods aimed at reducing direct contact between infected animals.

Visna/maedi virus (VMV) causes a slow and fatal disease in sheep. It is mainly associated with clinical symptoms of chronic interstitial pneumonia, but it is also linked to other clinical conditions such as arthritis, encephalitis and mastitis. The disease is widespread throughout the world and the infection has considerable historical importance. It gave rise to the discovery of slow viral infections and pointed to the difficulty in controlling them in international trade. Moreover, while it does not affect humans, it was first described within the group in which AIDS was subsequently included.

The studies carried out by Dr. Iratxe Leginagoikoa, PhD, have shown that VMV horizontal transmission is more important than vertical transmission. Thereby the need to detect infected animals rapidly, rearing the flocks in good conditions of space and ventilation and, reduce contact with infected animals in order to avoid its propagation within the flock.

Intensive stabling increases infection

During the first part of the study transmission of VMV through direct contact was monitored amongst 190 one-year-old lambs of the Latxa breed. Animals were divided into two groups: one subjected to horizontal infection at high pressure and the other kept in a well-aired enclosure without contact with infected animals. In the first group infection increased by 57 %, while no infection was detected in the second group.

This first study identified a close association between flock handling and stabling conditions and transmission of the infection by direct contact. To test this hypothesis, Neiker-Tecnalia scientists designed a three-year research programme with 38 ovine flocks under three different husbandry systems in Spain: the Latxa dairy sheep under semi-intensive farming (the Basque Country), the Assaf dairy sheep produced in Castile-Len under intensive farming and the extensive farming of crossed Manchego sheep in Castile-La Mancha. The study determined a seroprevalence (percentage of animals having antibodies against visna maedi virus) of 25 % of the semi-intensive flocks of the Basque Country, 77 % amongst the intensive flocks of Castile-Leon and 5 % amongst the extensively grazed flocks of Castile-La Mancha.

These results showed that whereas visna/maedi virus is not very prevalent amongst grazing flocks in extensive farming it is potentially highly prevalent amongst flocks in intensive sytem, where animals spend longer periods indoors thus increasing chances of virus transmission. Therefore, it is concluded that vertical transmission, which was once thought to be the only relevant transmission route, is, indeed, incapable by itself of maintaining VMV in the population. From this conclusion it can be gathered that eliminating the virus from flocks in extensive production systems could be simple and economically achieved by culling infected animals and feeding replacement lambs with virus-free colostrum and milk.

The possible link between new yearly acquired infections with variables indicative of horizontal infection pressure and maternal inheritance was also investigated. Results showed that lambs born to seropositive mothers became infected with greater frequency than the offspring of seronegative mothers.

ELISA and PCR

The results of this work also indicated that the analysis of blood using commercial ELISA methods for the detection of antibodies enables the reliable detection of VMV infection in adult sheep. However, these methods were not so effective in young animals or when viral load was low. In these cases, PCR, more expensive but able to detect the presence of the virus directly, would enable the detection of those infected animals which had not yet developed sufficient antibodies against the virus.

To verify this hypothesis, serum, blood clots and white blood cells were collected from 25 seronegative animals and 25 seropositive animals, confirmed as such with the ELISA technique. PCR detected the presence of the virus in up to 25 % of the negative ELISA samples and in all the positive ones, demonstrating the better performance of PCR. Especially noteworthy was the ability to detect VMV in blood clots, this representing the first report on the use of PCR protocols for VMV detection based on blood clot DNA. In addition to the higher sensitivity of the test, this novel protocol avoids the need for purifying leucocytes before DNA extraction, and opens a new door for the diagnosis of the infection through blood clot samples.


'/>"/>

Contact: Amaia Portugal
a.portugal@elhuyar.com
34-943-363-040
Elhuyar Fundazioa
Source:Eurekalert

Related biology news :

1. Neiker-Tecnalia underlines the need to maintain programs for monitoring pathogens in wildlife
2. Neiker-Tecnalia study use of oilseedrape and sunflower oils to produce fuel and feed for herds
3. Neiker-Tecnalia confirms need to undertake epidemiological monitoring programs for ticks
4. Trustee makes donation to start new solar energy research center at Rensselaer
5. What makes an axon an axon?
6. Feed a cold, feed a fever: Research shows calorie cut makes it harder to fight flu
7. Fly guy makes memory breakthrough
8. Our unconscious brain makes the best decisions possible
9. Biophysical Reviews makes debut in 2009
10. Tree lizard’s quick release escape system makes jumpers turn somersaults
11. Rett Syndrome Research Trust advisor makes significant discovery
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/3/2017)... , Feb. 3, 2017 A new ... Identity Strategy Partners, LLP (IdSP) . Designed to fill ... the complex identity market, founding partners Mark Crego ... 35 combined years just in identity expertise that span ... and non-profit leadership. The Crego-Kephart combined expertise has a ...
(Date:2/1/2017)... 2017 IDTechEx Research, a leading provider of ... the availability of a new report, Sensors for Robotics: Technologies, ... Reading ... ... Source: IDTechEx Report "Sensors for Robotics: Technologies, Markets and Forecasts 2017-2027: ...
(Date:1/26/2017)... -- Acuity Market Intelligence today released the 2017 "Ten ... characterizes 2017 as a "breakout" year for biometrics ... new understanding of the potential benefits these technologies ... are often perceived as threats to privacy and ... Acuity Market intelligence. "However, taken together these technologies ...
Breaking Biology News(10 mins):
(Date:2/24/2017)... NY (PRWEB) , ... February 24, 2017 , ... FireflySci, ... Founded in late 2014, FireflySci had the goal of bringing their powerful ... goal continues to shape the path that FireflySci is going on as they add ...
(Date:2/24/2017)... 2017  OncoSec Medical Incorporated ("OncoSec") (NASDAQ: ONCS), a ... Key Opinion Leader event to highlight new clinical data ... presentation at the upcoming 2017 ASCO-SITC Immuno-Oncology Symposium and ... be held in-person and via live webcast on Tuesday, ... PST at the Lotte New York Palace Hotel in ...
(Date:2/23/2017)... ... 2017 , ... BellBrook Labs is formalizing a significant expansion ... biochemical analyses critical for Lead Discovery. The company’s Lead Discovery Services will ... inhibitor potency and selectivity, mechanism of action, and inhibitor residence times on drug ...
(Date:2/23/2017)... -- In Atlanta, it seems everyone has a chance to express ... an expressive and dynamic community unlike any other. The businesses ... it. With their newest salon in ... carry on that tradition with a unique, fresh approach to ... is the newest of 13 nationwide locations, each of them ...
Breaking Biology Technology: