A farmer presenting with fever off and on for the past 4 years was diagnosed to be suffering from chronic Brucellosis. All of the following serological tests would be helpful in the diagnosis at this state except:

Option 1, 2, 4 - Acute infection: Standard agglutination test (SAT) - This test detects mainly IgM antibodies which are absent in chronic brucellosis. - SAT performed with 2-mercaptoethanol treated with serum will detects only IgG - Blocking antibodies--IgA antibodies that interfere with agglutination by IgG and IgM. They appear during the subacute stage of infection, tend to persist for many years- detected by the Coombs test Option 3 - CFT and ELISA: Are preferred in chronic brucellosis for Ab detection. Other Tests: PCR using primers for rrs-rrl gene, Omp2 gene Brucellin skin test Diagnosis of Brucellosis in Animals: Antibody detection in milk by (i) Milk ring test,(ii) Rose Bengal card test and (iii) Whey agglutination test