– World’s first successful use of immunochromatographic assay for direct detection of ZIKA virus in blood
– Developer seeks partnerships with domestic and overseas medical manufacturers to promote practical application
Tanaka Holdings Co., Ltd. has announced that Tanaka Kikinzoku Kogyo K.K., which operates the Tanaka Precious Metals manufacturing business, has developed the world’s first kit able to directly detect the ZIKA virus (ZIKV)*1 in blood. The kit is capable of rapid ZIKV detection in just 10 to 15 minutes. Tanaka Kikinzoku Kogyo plans to supply samples for clinical evaluation with a view to collaboration with domestic and overseas medical manufacturers.
Characteristics of detection kit
By making it possible for the first time to directly detect ZIKV in blood by immunochromatographic assay*2, the kit realizes simpler, faster and lower cost detection than existing methods.
Characteristic (1): world’s first kit to detect ZIKV via immunochromatographic assay
There is already an immunochromatographic assay method in practical application that detects the antibodies created in the human body following ZIKV infection, but the new kit makes it possible for the first time to directly detect ZIKV itself when present in the blood. By applying its unique antibody screening technology*3 and nano-colloidal gold*4, Tanaka Kikinzoku Kogyo has developed the new kit using antibodies to nonstructural protein (NS1) in ZIKV, allowing ZIKV to be detected at a concentration of 102TCID50/mL*5. This detection performance equals the sensitivity of other immunochromatographic assay-based test kits for influenza and other pathogens.
Characteristic (2): simpler, faster and lower in cost than existing methods
The existing method used for detecting ZIKV in blood is PCR*6, which requires special equipment and takes between half a day and one day to complete. With the new kit, however, the test strip only needs to be dipped into the test sample to enable ZIKV detection. Additionally, it allows detection in 10 to 15 minutes, equaling the simplicity and speed of the influenza virus detection kit already in practical application. Furthermore, unlike PCR, it does not require special equipment, thus realizing cost savings for users.
Background to development of detection kit
ZIKV infection has been spreading since 2015, particularly in Brazil. Infected people develop commonly Zika fever, with symptoms of fever and conjunctival congestion. If pregnant women become infected with ZIKV, there are indications that the fetus may develop microcephaly, which is an abnormal smallness of the head, a congenital condition associated with incomplete brain development. As the possibility has been indicated of infection not only through mosquitoes, but also through blood transfusions and sexual contact, a kit is required which can perform direct and specific detection in the early stage after infection using a fast and simple method. The simple ZIKV detection kit that is currently commercially available detects the antibodies to ZIKV (immunoglobulin G and immunoglobulin M) that are producted in the bodies of infected humans, and is therefore not suited to diagnosing Zika fever in the initial stage of infection. In order to make possible early identification of ZIKV infection, Tanaka Kikinzoku Kogyo applied its store of technology, its unique antibody screening technology, and the nano-colloidal gold manufacturing technologies which it has accumulated over many years to develop a kit capable of direct detection of the virus itself.
It is hoped that the development of the new kit will be highly effective in suppressing the spread of ZIKV infection.
The spread of ZIKV has become a worldwide threat, with the World Health Organization (WHO) declaring on February 1, 2016, that the Zika fever it causes represents a ‘public health emergency of international concern’. It is estimated that more than 4 million people are already infected on the South and North American continents. Specifically in Brazil, there is reportedly concern that this summer’s Rio Olympics will see a further spread of the infection.
*1 ZIKA virus: ZIKA virus is the virus that causes ZIKA virus infection. Normally, ZIKA virus infection is transmitted by the bite of a mosquito that carries the ZIKA virus, but fetal infection has also been found to occur. The possibility of infection through blood transfusions and sexual contact has additionally been indicated.
*2 Immunochromatographic assay: An analytical method enabling visual determination of the concentration of a target molecule is above or below a specified threshold of concentration by reacting colored- particle labeled antibodies immobilized on the test strip with a liquid sample which is drawn into the test strip by capillary action. The new kit uses as its labeling dye nano-colloidal gold, which turns red.
*3 Antibody screening technology: A technology which selects antibodies suited to the target purpose from among a range of antibodies.
*4 Nano-colloidal gold: Colloidally dispersed particles of nano-sized gold as a means to generate visualized color of the assay signal.
*5 TCID50/mL: Median tissue culture infectious dose, a unit of viral infectivity titer. It denotes the virus concentration at which 50% of cultured cells are infected following inoculation with a diluted virus sample.
*6 PCR (Polymerase Chain Reaction): An analytical technique involves the amplification of a single or few copies of a piece of DNA to generate thousands to millions copies of a particular DNA sequence through an enzymatic assembling of the nucleotides.
Source: Tanaka Holdings Co., Ltd.