Phonemical approach in diagnostics! | By Anam Munir 


Phonemical approach in diagnostics!

LIVESTOCK has contributed consid erably to the economy of the world. However, there is still major threat for food security, economic growth and poverty reduction due to animal diseases.

Foot-and-mouth disease (FMD) is a trans-boundary disease that is also one of the most economically overwhelming diseases among livestock animals, causing major output losses in all cloven-hoofed animals.

FMD is extremely contagious, multispecies animal disease that has a severe effect on national and international economical trade.

Global effects of disease are reported by World Organization for Animal Health. The Pirbright institute is world reference laboratory designated by FAO (Food and agriculture organization) and OIE (office International des epizooties).

Pakistan has big livestock and small animals industry, moreover, life in rural areas is more dependent over livestock wellbeing.

Neighbouring countries like India, Afghanistan, Iran and China are linked to the Pakistan with its borders.

Free and illegal transportation of animals leads spread of various strains of virus across the border. The direct economic losses are up to 33% in endemic areas.

In FMD affected animals, 80% of milk production loss can occur and the mortality rate can be higher in calves. Moreover, FMD also causes in abortion in pregnant animals.

The national and international trade of animals and animal products is being highly affected by FMD status, so leading to economic disaster. High prevalence of FMD in Pakistan effects the export of livestock and their products in international market.

Foot and Mouth disease is prevalent in certain areas of Pakistan and outbreaks occur commonly, resulting in significant economic loss in livestock and small animas health.

There are seven serotypes of FMDV among which serotype O, A, Asia 1 are present in Pakistan.

Serotype O-Pan Asia strain has caused an explosive pandemic in Asia. FMDV’s genome is 8003bp long, single stranded, positive sense RNA.

Vaccination is not properly done in developing countries and failure to effective vaccination may result in pandemic. In most studies it is stated that VP1 is the major protein responsible for antigenic variation.

Any change in the genetic makeup of VP1 protein can interface by lowering activity of the previous vaccination. Chances of disease occurrence in human being are very low.

To control this disease various approaches are being used, such as culling programs and animal movement restrictions in and out of infected areas along with vaccination, which is the most effective tool.

Novel vaccines, such as engineered attenuated viruses, recombinant DNA immunization, or peptide subunits, have been developed.

Latest researches have proved that intact virus (146S FMDV) provides effective immunogenicity in animals.

Gold standard method to measure quantity of 146S fraction or intact virus of FMDV is Sucrose Density Gradient Ultracentrifugation (SDG-Ultracentrifugation). SDG Ultracentrifugation is expensive, laborious and time consuming technique.

Alternatively, cost effective, technically easy and quick technique was introduced named as Double antibody sandwich-enzyme linked immunosorbent essay (DAS ELISA).

DAS ELISA provides rapid and cheap quantitative detection of 146S not only during production but also at the time of application of vaccine

For the first time, in this project, both sucrose density gradient and DAS ELISA were used side by side for the quantification of 146S of FMD virus. A strong correlation was found between both of the above mentioned test.

In comparison to SDG, the DAS-ELISA was proven to be easy and was able to quantify large number of sample simultaneously.

—The writer is contributing columnist, based in Lahore.

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