Characterization of Differential Antibody Production against Hepatitis C Virus in Egyptian Chronic HCV Infection and Healthcare Workers
Doaa Essam Eldein Mahmoud Shalaby;
Abstract
SUMMARY
H
CV has been found to be an important cause of liver disease and remains a major public health problem worldwide. According to the World Health Organization, nearly 3% of the world population has been infected with HCV. Therefore, more than 170 million people are chronic carriers of HCV and at high risk of developing liver cirrhosis and/or hepatocellular carcinoma (HCC). Three to 4% of chronically infected individuals develop fatal HCC. Currently, HCC caused by HCV infection is considered an indication for liver transplantation.
HCV antibody screening tests with enzyme-linked immunosorbent assays (ELISA), were proven to be both highly reliable and cost effective, which led to their almost universal utilization as a first-level screening procedure. However, both false positive (HCV-positive according to ELISA, but negative with a second-level recombinant immunoblot assay (RIBA)) and indeterminate results (neither negative nor positive results to anti-HCV antibody dosage (HCV-positive with ELISA, indeterminate results with RIBA) may occur.
EIA test may give false-positive results due to possible nonspecific reactivity, especially to c100-3 antigen. RIBA is the preferred supplementary serological testing method due to its robust specificity. RIBA testing requires the identification of false-positive results using ELISA.
The humoral response to HCV infection is broadly targeted, with antibodies to both structural and non-structural proteins found in most cases. Although the commercial methodology to detect HCV-specific RNA and antibody responses in patient sera has greatly advanced in recent years there is no detailed information of the immunogenicity of different HCV proteins in patients suffering from chronic HCV infection. On the other hand, healthy carriers of hepatitis C virus (HCV) infection exhibit a specific antibody response against HCV antigens, which could play a role in disease control. Detection of these antibodies may permit a thorough characterization of this response and further identify particular antibodies with potential clinical value.
The aim of the study was to determine qualitative differences in host antibody responses to different HCV proteins in Egyptian chronic HCV infection and healthy care workers and their correlation to clinical outcome.
The current study was conducted on 167 individuals divided into three groups:
Group I: included 77 high risk health care workers (HCWs) who worked at Ain Shams University laboratory and blood bank and were thus considered a high risk health care population. Group II: included 56 patients enrolled from Ain Shams University Hospital who were well characterized asymptomatic patients with HCV RNA negative. Group III: enrolled from outpatient, clinics of Ain Shams University Hospital with persistent viral replication and chronic HCV related liver disease.
After an informed consent, all individuals included in this study were subjected to full history taking, through clinical examination and the following laboratory investigation: AST and ALT level, Anti-HCV Ab by 3rd generation ELISA, quantitative determination of HCV RNA by Real time –PCR and determination of antibodies to core and non structural HCV proteins using recombinant immunoblot assay (RIBA). Results of this study revealed the following:
1- A total of 167 blood samples were used to compare RIBA test results with those of anti-HCV antibodies by 3rd generation ELISA. Of these samples, 123 were anti-HCV antibodies positive, 5 were negative and 39 were indeterminate. When RIBA testing was performed out of 123 anti-HCV antibodies positive by ELISA, 96 were positive,6 were indeterminate and 21 were negative.
2- Comparison of RIBA results with those of anti-HCV antibodies by ELISA, in different studied groups revealed that true positive cases were highly significantly increased in chronic hepatitis 91.2% (31/34), followed by HCW 71.4% (55/77) than normal group 48.2% (27/56). False positive cases were highly significant increase in HCW 28.6% (22/77) when compared with normal 8.9% (5/56) and chronic 8.8% (3/34). While indeterminate and false negative were only present in normal.
3- Comparative statistics of RIBA results in different studied group revealed that Indeterminate RIBA results were highly significant in the normal group 41.1% (23/56) when compared with HCW 3.9% (3/77) and with chronic liver disease 5.9% (2/34). While negative RIBA results were highly significant in HCW when compared with chronic liver disease and normal group.
4- For differentiated antibody responses by RIBA HCV Core 1and 2 antigen were highly significant increase in chronic 91.2%, 76.5% when compared with HCW (70.1%, 68.9%) and normal group (48.2%, 46.4%) respectively. Moreover, Core 1and 2 in HCW proved to be highly significant increase when compared with normal i.e chronic HCV cases had the highest frequency of positive antibody response to core peptides while the normal group had the lowest.
5- Antibody responses to E2 was found less frequently in chronic cases 35.3% than Core 1, Core 2 and NS3 (91.2%, 76.5% and 97.1% respectively). Comparison of E2 between studied groups revealed non-significant different between chronic (35.3%) and HCW (28.6%). There was a highly significant increase in antibody reponses to E2 in chronic HCV cases when compared with the normal group and a significant increase in HCW when compared to the normal group.
6- Antibody responses to NS3 were found highly significantly increased in chronic HCV cases (97.1%) when compared with the normal group (78.6%) and with the HCW (65%). While NS3 in HCW was found to be highly significantly decreased when compared with the normal group.
7- Antibody responses to NS4 were highly significantly increased in chronic HCV cases 67.6% when compared with HCW 46.8% and with normal individuals 16.1%. Similarly the HCW showed a highly significant increase when compared with normal individuals.
8- Antibody responses to NS5 were found less frequently in chronic HCV cases 44.1% when compared with NS4 (67.6%). However, comparison between the studied groups revealed a highly significant increase in reactivity to NS5 peptides in chronic HCV cases (44.1%) when compared to both with normal group and HCW. A significant increase in reactivity to NS5 peptides were found in HCW when compared with the normal group.
9- Study the frequencies of the specific antibody response to the different HCV peptides, revealed that chronic HCV cases and the normal individuals had the same distribution of frequencies with the chronic cases having the highest frequencies. This distribution was different from the HCW. The most evident difference was the reaction towards NS3 which was the highest in antibody producing peptide in chronic HCV and normal individuals whereas in HCW C1 was the highest.
10- Multiple regression analysis was carried out to detect the HCV antigens that differentiate chronic from HCW and normal. The presence of antibodies against both Core 2 and NS3 in chronic HCV cases can differentiate chronic from HCW with Odd,s Ratio 12.38 .While the presence of antibodies against both Core 1 and NS4 in chronic HCV cases can differentiate chronic from normal with Odd,s Ratio 10.33
H
CV has been found to be an important cause of liver disease and remains a major public health problem worldwide. According to the World Health Organization, nearly 3% of the world population has been infected with HCV. Therefore, more than 170 million people are chronic carriers of HCV and at high risk of developing liver cirrhosis and/or hepatocellular carcinoma (HCC). Three to 4% of chronically infected individuals develop fatal HCC. Currently, HCC caused by HCV infection is considered an indication for liver transplantation.
HCV antibody screening tests with enzyme-linked immunosorbent assays (ELISA), were proven to be both highly reliable and cost effective, which led to their almost universal utilization as a first-level screening procedure. However, both false positive (HCV-positive according to ELISA, but negative with a second-level recombinant immunoblot assay (RIBA)) and indeterminate results (neither negative nor positive results to anti-HCV antibody dosage (HCV-positive with ELISA, indeterminate results with RIBA) may occur.
EIA test may give false-positive results due to possible nonspecific reactivity, especially to c100-3 antigen. RIBA is the preferred supplementary serological testing method due to its robust specificity. RIBA testing requires the identification of false-positive results using ELISA.
The humoral response to HCV infection is broadly targeted, with antibodies to both structural and non-structural proteins found in most cases. Although the commercial methodology to detect HCV-specific RNA and antibody responses in patient sera has greatly advanced in recent years there is no detailed information of the immunogenicity of different HCV proteins in patients suffering from chronic HCV infection. On the other hand, healthy carriers of hepatitis C virus (HCV) infection exhibit a specific antibody response against HCV antigens, which could play a role in disease control. Detection of these antibodies may permit a thorough characterization of this response and further identify particular antibodies with potential clinical value.
The aim of the study was to determine qualitative differences in host antibody responses to different HCV proteins in Egyptian chronic HCV infection and healthy care workers and their correlation to clinical outcome.
The current study was conducted on 167 individuals divided into three groups:
Group I: included 77 high risk health care workers (HCWs) who worked at Ain Shams University laboratory and blood bank and were thus considered a high risk health care population. Group II: included 56 patients enrolled from Ain Shams University Hospital who were well characterized asymptomatic patients with HCV RNA negative. Group III: enrolled from outpatient, clinics of Ain Shams University Hospital with persistent viral replication and chronic HCV related liver disease.
After an informed consent, all individuals included in this study were subjected to full history taking, through clinical examination and the following laboratory investigation: AST and ALT level, Anti-HCV Ab by 3rd generation ELISA, quantitative determination of HCV RNA by Real time –PCR and determination of antibodies to core and non structural HCV proteins using recombinant immunoblot assay (RIBA). Results of this study revealed the following:
1- A total of 167 blood samples were used to compare RIBA test results with those of anti-HCV antibodies by 3rd generation ELISA. Of these samples, 123 were anti-HCV antibodies positive, 5 were negative and 39 were indeterminate. When RIBA testing was performed out of 123 anti-HCV antibodies positive by ELISA, 96 were positive,6 were indeterminate and 21 were negative.
2- Comparison of RIBA results with those of anti-HCV antibodies by ELISA, in different studied groups revealed that true positive cases were highly significantly increased in chronic hepatitis 91.2% (31/34), followed by HCW 71.4% (55/77) than normal group 48.2% (27/56). False positive cases were highly significant increase in HCW 28.6% (22/77) when compared with normal 8.9% (5/56) and chronic 8.8% (3/34). While indeterminate and false negative were only present in normal.
3- Comparative statistics of RIBA results in different studied group revealed that Indeterminate RIBA results were highly significant in the normal group 41.1% (23/56) when compared with HCW 3.9% (3/77) and with chronic liver disease 5.9% (2/34). While negative RIBA results were highly significant in HCW when compared with chronic liver disease and normal group.
4- For differentiated antibody responses by RIBA HCV Core 1and 2 antigen were highly significant increase in chronic 91.2%, 76.5% when compared with HCW (70.1%, 68.9%) and normal group (48.2%, 46.4%) respectively. Moreover, Core 1and 2 in HCW proved to be highly significant increase when compared with normal i.e chronic HCV cases had the highest frequency of positive antibody response to core peptides while the normal group had the lowest.
5- Antibody responses to E2 was found less frequently in chronic cases 35.3% than Core 1, Core 2 and NS3 (91.2%, 76.5% and 97.1% respectively). Comparison of E2 between studied groups revealed non-significant different between chronic (35.3%) and HCW (28.6%). There was a highly significant increase in antibody reponses to E2 in chronic HCV cases when compared with the normal group and a significant increase in HCW when compared to the normal group.
6- Antibody responses to NS3 were found highly significantly increased in chronic HCV cases (97.1%) when compared with the normal group (78.6%) and with the HCW (65%). While NS3 in HCW was found to be highly significantly decreased when compared with the normal group.
7- Antibody responses to NS4 were highly significantly increased in chronic HCV cases 67.6% when compared with HCW 46.8% and with normal individuals 16.1%. Similarly the HCW showed a highly significant increase when compared with normal individuals.
8- Antibody responses to NS5 were found less frequently in chronic HCV cases 44.1% when compared with NS4 (67.6%). However, comparison between the studied groups revealed a highly significant increase in reactivity to NS5 peptides in chronic HCV cases (44.1%) when compared to both with normal group and HCW. A significant increase in reactivity to NS5 peptides were found in HCW when compared with the normal group.
9- Study the frequencies of the specific antibody response to the different HCV peptides, revealed that chronic HCV cases and the normal individuals had the same distribution of frequencies with the chronic cases having the highest frequencies. This distribution was different from the HCW. The most evident difference was the reaction towards NS3 which was the highest in antibody producing peptide in chronic HCV and normal individuals whereas in HCW C1 was the highest.
10- Multiple regression analysis was carried out to detect the HCV antigens that differentiate chronic from HCW and normal. The presence of antibodies against both Core 2 and NS3 in chronic HCV cases can differentiate chronic from HCW with Odd,s Ratio 12.38 .While the presence of antibodies against both Core 1 and NS4 in chronic HCV cases can differentiate chronic from normal with Odd,s Ratio 10.33
Other data
| Title | Characterization of Differential Antibody Production against Hepatitis C Virus in Egyptian Chronic HCV Infection and Healthcare Workers | Other Titles | توصيف إنتاج الأجسام المضادة المتنوعة ضد الإلتهاب الكبدى الوبائي ج في مرضي الإلتهاب الكبدي الوبائي ج المزمن و العاملين بالرعاية الصحية | Authors | Doaa Essam Eldein Mahmoud Shalaby | Issue Date | 2015 |
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