676 TRANSACTIONS OF THE ROYAL SOCIETY OF
TROPICAL MEDICINE
AND
HYGIENE (1992) 86, 676
-Report Hepatitis Africa
C virus testing
of sera in
Antonio Aceti and Gloria Taliani Istituto di Clinica delle Malattie Tropicali e Infcttive, Universitd ‘La Sapienza’, Roma, Italia
The cloning and sequencing of hepatitis C virus (HCV) (CHOO et al., 1989) and the development of serological assaysto detect antibody to this virus (KUO et al., 1989)provide an opportunity to redefine and expand our knowledge of the epidemiology of HCV infection. Before planning serological surveys, it is important that the test involved is assessedrigorously to obtain reliable data. Preliminary studies have raised doubts about the specificity of an enzyme-linked immunosorbent assay (ELISA)in detecting anti-HCV antibody in serum samples from populations living in developing countries (ACETI et al., 1990; COURSACET et al., 1990; WONC et al., 1990; TIBBSet al., 1991). We recently evaluated the specificity of this ELBA with normal donors living in tropical communities. For this purpose, sera from 90 African donors (33 from Mogadishu, Somalia, 25 from Mbalmayo, Cameroon, and 22 from Mbabane, Swaziland) found by ELISA(HCV ELISA Test System 2nd Generation Ortho@ , Raritan, New Jersey) to be repeatedly reactive for anti-HCV were selected for confirmatory testing with a second-generationrecombinant immunoblot assay(RIBA-2) (RIBAHCV Test System 2nd Generation@, Chiron, Emeryville, California). No donor had a history of parenteral exposure to blood or blood products, a clinical or pathological picture compatible with viral hepatitis, or any other apparent cause of liver disease. Table. Results of hepatitis C virus recombinant immunoblot assay (RIBA-2) on sera positive by enzymelinked immunosorbent assay (ELISA) according to absorbance values
ELISA absorbance value tl.1 1.1-2.4
No. of sera tested
>2*4
30 90
Total
:i
No. positive by RIBA0
3 (10%) 20 (66.7%) 23 (25.5%)
Of the sera positive by ELISA, 30 had an absorbence value over 2.4 and were scored as ‘strongly’ reactive, 30 had absorbencies between 2.4 to 1.1 and were scored as ‘intermediate’, and 30 with absorbenciesbelow 1.1 were scored as ‘weakly’ reactive. According to the RIBA- procedure, 23 sera (25.6%) gave a positive test result *Author for correspondence: Dr A. Aceti,, Istituto di Clinica delle Malattie Tropicali e Infettive, Pohclinico Umberto I, 00161Roma, Italia.
(samplesreacting with 2 or more viral antigens), 4 (4.4%) gave an indeterminate test result (samples reacting with only one band), and 63 (70%) gave a negative result (samples not reacting with any bands). The RIBA- results correlated with the ELISAvalue. The RIBA- positivity rate was about 67% in ELISAstrongly reactive seraand 10% in intermediate sera, whereas no positive result wgs obtained with the weakly reactive sera (P
TROPICAL MEDICINE
AND
HYGIENE (1992) 86, 676
-Report Hepatitis Africa
C virus testing
of sera in
Antonio Aceti and Gloria Taliani Istituto di Clinica delle Malattie Tropicali e Infcttive, Universitd ‘La Sapienza’, Roma, Italia
The cloning and sequencing of hepatitis C virus (HCV) (CHOO et al., 1989) and the development of serological assaysto detect antibody to this virus (KUO et al., 1989)provide an opportunity to redefine and expand our knowledge of the epidemiology of HCV infection. Before planning serological surveys, it is important that the test involved is assessedrigorously to obtain reliable data. Preliminary studies have raised doubts about the specificity of an enzyme-linked immunosorbent assay (ELISA)in detecting anti-HCV antibody in serum samples from populations living in developing countries (ACETI et al., 1990; COURSACET et al., 1990; WONC et al., 1990; TIBBSet al., 1991). We recently evaluated the specificity of this ELBA with normal donors living in tropical communities. For this purpose, sera from 90 African donors (33 from Mogadishu, Somalia, 25 from Mbalmayo, Cameroon, and 22 from Mbabane, Swaziland) found by ELISA(HCV ELISA Test System 2nd Generation Ortho@ , Raritan, New Jersey) to be repeatedly reactive for anti-HCV were selected for confirmatory testing with a second-generationrecombinant immunoblot assay(RIBA-2) (RIBAHCV Test System 2nd Generation@, Chiron, Emeryville, California). No donor had a history of parenteral exposure to blood or blood products, a clinical or pathological picture compatible with viral hepatitis, or any other apparent cause of liver disease. Table. Results of hepatitis C virus recombinant immunoblot assay (RIBA-2) on sera positive by enzymelinked immunosorbent assay (ELISA) according to absorbance values
ELISA absorbance value tl.1 1.1-2.4
No. of sera tested
>2*4
30 90
Total
:i
No. positive by RIBA0
3 (10%) 20 (66.7%) 23 (25.5%)
Of the sera positive by ELISA, 30 had an absorbence value over 2.4 and were scored as ‘strongly’ reactive, 30 had absorbencies between 2.4 to 1.1 and were scored as ‘intermediate’, and 30 with absorbenciesbelow 1.1 were scored as ‘weakly’ reactive. According to the RIBA- procedure, 23 sera (25.6%) gave a positive test result *Author for correspondence: Dr A. Aceti,, Istituto di Clinica delle Malattie Tropicali e Infettive, Pohclinico Umberto I, 00161Roma, Italia.
(samplesreacting with 2 or more viral antigens), 4 (4.4%) gave an indeterminate test result (samples reacting with only one band), and 63 (70%) gave a negative result (samples not reacting with any bands). The RIBA- results correlated with the ELISAvalue. The RIBA- positivity rate was about 67% in ELISAstrongly reactive seraand 10% in intermediate sera, whereas no positive result wgs obtained with the weakly reactive sera (P
