6. Prozoning may sometimes be encountered in serum

containing very high titers on slide test.

7. Since techniques and standardization vary from

laboratory to laboratory a difference of titer corresponding to next or previous titer can be expected.

BRUCELLOSIS POSITIVE CONTROL

(Courtesy: Tulip Group of Companies)

Summary

Human brucellosis (diurnal, or undulant fever) is a

common febrile illness caused by infection with bacteria

of some of the Brucella species (abortus, melitensis). This

undulant fever is associated with symptoms, which are

often variable and nonspecific with chills, fever, sweats and

anorexia. On exposure, the body responds to this antigenic

stimulation by producing specific antibodies whose titers

rise slowly at early stages and then increases. Specific antibodies to the Brucella species are detectable a few weeks

after exposure and are of considerable importance in the

Serology/Immunology 639

diagnosis of Brucellosis. Information regarding the titer

of antibodies can be obtained by using specific Brucel

antigen suspensions.

The performance of the Brucel-A/Brucel-M antigen

suspensions can be validated with the help of Brucellosis

Positive Control.

Reagent

The Brucellosis Positive Control contains ready-to-use

standardized goat antiserum with polyspecific antibodies

having specific reactivity towards Brucella abortus and

Brucella melitensis antigens and is useful in the validation

of the performance of Brucel-A/Brucel-M reagents.

Reagent Storage and Stability

Store the reagent at 2 to 8°C. Do not freeze.

The shelf-life of the reagent is as per the expiry date

mentioned on the reagent bottle label.

Each batch of reagents undergoes rigorous quality

control at various stages of manufacture for its specificity,

sensitivity, and performance.

Principle

The Brucellosis Positive Control is mixed with the

Brucella antigen suspensions to be tested and allowed to

react. Specific reactivity of Brucella antigens if present in

the antigen suspensions will produce an agglutination

reaction. No agglutination indicates the deterioration of

the performance of the antigen suspensions.

Note

1. In vitrodiagnostic reagent for laboratory and professional

use only. Not for medicinal use.

2. The reagent contains thimerosal 0.01% as preservative.

Avoid contact with skin and mucosa. On disposal,

flush with large quantities of water.

Additional Material Required

Stopwatch, isotonic saline, glass slide with clear/white

background, appropriate pipettes/micropipettes, mixing

sticks and a high intensity direct light source.

Procedure

Bring all reagents to room temperature. Shake and mix the

Brucellosis Positive Control well before dispensing.

Slide Test Method

1. Place one drop of Brucellosis Positive Control onto the

reaction circle of glass slide.

2. Place 80 µL of saline onto the next reaction circle of

the glass slide.

3. Add one drop of test reagent (Brucella antigen

suspensions) in each of the above circles.

4. Mix contents of each circle uniformly over the entire

circle with separate mixing sticks.

5. Gently rock the slide back and forth, observe for

agglutination macroscopically at 1 minute against a

white background.

Interpretation of Results

Slide Test Method

Agglutination is a positive test result and indicates that the

Brucella antigen reagents are performing satisfactorily.

No agglutination is a negative test result and indicates the

deterioration of Brucella antigen reagents.

RAPID TEST FOR IgM AND IgG ANTIBODIES TO

DENGUE VIRUS: DENGUE FEVER

(DENGUECHECK-WB) (DEVICE)

(Courtesy: Tulip Group of Companies)

Introduction

Denguecheck-WB is a rapid immunochromatographic test

for the simultaneous detection of IgM and IgG antibodies

to Dengue virus in human serum/plasma/whole blood.

The test can be used as a screening test for Dengue viral

infection and as an aid for differential diagnosis of the selflimiting primary Dengue infections and the potentially

fatal secondary Dengue infections in conjunction with

other criteria.

Summary

Dengue fever virus (serotypes 1–4) belong to the family of

Flaviviridae, which is widely distributed in the epidemic

and endemic areas throughout tropical and subtropical

regions of the world. Dengue virus infection is considered

significant in terms of morbidity, mortality and economic cost

associated with it, an estimated 100 million cases of dengue

fever occurring throughout the world yearly. Dengue virus

is transmitted in nature principally by the day-biting Aedes

aegypti and Aedes albopictus mosquitoes. The mosquito

vector is highly domesticated and an urban species. Dengue

presents typically as a fever of sudden onset with headache,

retro-orbital pain, pain in the back and limbs (break-bone

fever), lymphadenopathy and maculopapular rash. Patients

diagnosed with dengue infection in endemic areas generally

have secondary infection, whereas patients in nonendemic

640 Concise Book of Medical Laboratory Technology: Methods and Interpretations areas are usually diagnosed with primary infection. Specific

antibody response to Dengue virus enables serodiagnosis

and differentiation between primary and secondary dengue

infections and detection of potentially life-threatening

conditions such as Dengue Hemorrhagic Fever (DHF) and

Dengue Shock Syndrome (DSS).

Denguecheck-WB is a new generation rapid

immunochromatographic test using highly specific and

purified immunodominant, Recombinant Dengue ‘Env.’

antigens. It is a simple test for the differential diagnosis of

Dengue virus infection.

Principle

Denguecheck-WB utilizes the principle of immunochromatography, a unique two-site, self-performing

immunoassay on a membrane. Specific human IgM and

human IgG antibody-binding proteins are immobilized on

the nitrocellulose membrane as two individual test bands

(IgM and IgG) in the test window “T” of the test device at

region “M” and region “G” respectively. The IgM band in

the test window “T” is closer to the sample well and the

IgG band is close to the control window “C”. As the test

sample flows through the membrane assembly within

the test device, the colored-Dengue specific recombinant

antigen-colloidal gold conjugate complexes with specific