Establishment and application of an indirect ELISA for Getah virus E2 antibody detection

Getah virus (GETV) is a mosquito-transmitted disease that affects animals, causing fever, aseptic meningitis, and abortion. Its prevalence in China poses risks to both animal health and public well-being. Currently, there is a scarcity of seroepidemiological data on GETV due to the absence of commercial antibody detection kits for pigs. The aim of this study is to develop a rapid, accurate, and sensitive ELISA, providing a reliable tool for GETV seroepidemiology and laying the foundation for future commercial assay development. In this study, we removed specific hydrophobic domains and intracellular structures from E2 proteins and constructed the recombinant plasmid pCold-TF-E2. The recombinant protein was expressed using a prokaryotic expression system, and efficient purification of the rE2 protein was achieved using a nickel affinity column. The purified rE2 protein is suitable for the development of an indirect ELISA (rE2 ELISA). Following the optimization of reaction conditions for the rE2-ELISA, the cut-off value was 0.356. Additionally, the rE2-ELISA method showed a positive rate of 37.1% for IgG antibodies against GETV when testing 986 pig clinical serum samples collected from pigs in Sichuan between May 2022 and September 2022. The rE2-ELISA method displayed a 95.1% overall agreement with VNT, boasting a sensitivity of 98.2% and a specificity of 92.6%. These results indicate that IgG ELISA based on rE2 protein is an efficient and economical method for the detection of GETV antibodies in pigs, facilitating the diagnosis and prevention of GETV.

[Seroepidemiological survey of Toxoplasma gondii infections in patients with diabetes mellitus in Hangzhou City]

OBJECTIVE

To investigate the seroprevalence of Toxoplasma gondii infections among patients with diabetes mellitus in Hangzhou City.

METHODS

A total of 337 patients with type 1 diabetes mellitus, 624 patients with type 2 diabetes mellitus and 384 patients with gestational diabetes mellitus living in Hangzhou City during the period from March 2017 through May 2020 were recruited as the study subjects, while age- and gender-matched healthy volunteers and pregnant women without gestational diabetes mellitus served as controls. Enzyme-linked immunosorbent assay (ELISA) was employed to detect serum IgG and IgM antibodies against T. gondii in patients with diabetes mellitus and controls, and the seroprevalence of anti-T. gondii antibody was compared between diabetes mellitus patients and controls.

RESULTS

The overall seroprevalence of anti-T. gondii antibody (18.10% vs. 4.45%, χ² = 31.38, P < 0.01) and the seroprevalence of anti-T. gondii IgG antibody (14.54% vs. 2.97%, χ² = 28.28, P < 0.01) were both significantly higher in patients with type 1 diabetes mellitus than in healthy controls, while no significant difference was seen in the seroprevalence of anti-T. gondii IgM antibody between patients and controls (3.56% vs. 1.48%, χ² = 2.96, P > 0.05). The seroprevalence rates of serum anti-T. gondii (23.56% vs. 6.57%, χ² = 70.37, P < 0.01) and anti-T. gondii IgG antibodies (21.15% vs. 5.45%, χ² = 66.73, P < 0.01) were significantly higher in patients with type 2 diabetes mellitus than in healthy controls, while no significant difference was seen in the seroprevalence of anti-T. gondii IgM antibody between patients and controls (2.40% vs. 1.12%, χ² = 2.96, P > 0.05). In addition, the overall seroprevalence of serum anti-T. gondii antibody (26.30% vs. 19.53%, χ² = 4.98, P < 0.05) and the seroprevalence of anti-T. gondii IgG antibody (23.70% vs. 17.71%, χ² = 4.20, P < 0.05) were both significantly higher in patients with gestational diabetes mellitus than in pregnant women without gestational diabetes mellitus, while no significant difference was seen in the seroprevalence of anti-T. gondii IgM antibody between pregnant women with and without gestational diabetes mellitus (2.60% vs. 1.82%, χ² = 0.54, P > 0.05).

CONCLUSIONS

The patients with diabetes mellitus present a higher seroprevalence rate of anti-T. gondii antibody than controls in Hangzhou City. Screening of T. gondii infections and health education pertaining to toxoplasmosis prevention and control knowledge should be reinforced in patients with diabetes mellitus.

[Seroepidemiological survey of Toxoplasma gondii infection in patients with gynecological malignant tumors]

OBJECTIVE

To investigate the seroprevalence of Toxoplasma gondii infection in patients with gynecological malignant tumors, so as to provide the evidence for the control of T. gondii infections in the patients with gynecological malignant tumors.

METHODS

A total of 327 patients with gynecological malignant tumors were recruited, and 200 women with normal healthy examinations were served as controls. The serum anti-T. gondii IgG and IgM antibodies were detected by using ELISA, and the seroprevalence was compared between the patients and controls, and among various types of cancers.

RESULTS

The overall seroprevalence of T. gondii was 26.91% (88/327) in the patients with gynecological malignant tumors, which was significantly higher than that (5.00%) in the healthy volunteers (χ² = 39.36, P<0.01) . The prevalence of anti-T. gondii IgG antibody in the cancer patients was significantly higher than that in the controls (26.30% vs. 5.00%; χ² = 37.79, P<0.01), while the prevalence of anti-T. gondii IgM antibody in the cancer patients was not significantly different from that in the controls (0.92% vs. 0; corrected χ² = 0.58, P > 0.01) . The positive rates of anti-T. gondii IgG antibody were 27.68%, 25.47% and 25.69% in ovarian cancer, cervical cancer, and breast cancer patients respectively, which were all significantly higher than those in the controls (χ² = 32.35, 27.32 and 28.00; all P values<0.01); however, there was no significant difference among the various types of cancer patients in the positive rates of anti-T. gondii IgG antibody (χ² = 0.17, P > 0.05) . In addition, the positive rates of anti-T. gondii IgM antibody were 1.79%, 0 and 0.92% in ovarian cancer, cervical cancer and breast cancer patients respectively, which was not significantly different from those in the controls (all P values > 0.05).

CONCLUSIONS

The seroprevalence of T. gondii infection is high in the patients with gynecological malignant tumors. It is suggested that the prevention and control of T. gondii infection should be strengthened in these patients.

[Seroepidemiological survey of Toxoplasma gondii infection among employees in a pork food processing enterprise]

OBJECTIVE

To understand the situation of seroepidemiology of Toxoplasma gondii infection among employees in a pork food processing enterprise in Dongtai City.

METHODS

Totally 200 employees from a pork food processing enterprise in Dongtai City were selected as the research objects. The venous blood of the selected population was extracted and the IgG antibody against T. gondii in serum was detected by ELISA, and the results were analyzed.

RESULTS

Among the 200 employees, 36 cases were positive in IgG antibody detection, the positive rate was 18.0%. The positive rate of IgG antibody among workers with different length of service was significantly different (χ² = 9.813, P < 0.05). With the increase of working age, the positive rate of IgG antibody gradually increased. The positive rate of IgG antibody to T. gondii was significantly higher in the population who had frequent contact with animals.

CONCLUSIONS

The positive rate of IgG antibody against T. gondii in employees in pork food processing enterprises is high. Therefore, the detection of antibodies against T. gondii and health education should be strengthened in this population.

The prevalence of diagnosed and undiagnosed hepatitis C virus infection in Navarra, Spain, 2014-2016

OBJECTIVE

To estimate the prevalence of hepatitis C virus (HCV) infection in Navarra, Spain, as well as to distinguish between diagnosed and undiagnosed infections.

METHODS

A study was conducted on patients scheduled for surgery unrelated to HCV infection. They were all tested for HCV antibodies, under a routine scheme, from January 2014 to September 2016. Patients with a positive result by enzyme immunoassay were confirmed using immunoblot and/or HCV-RNA. Previous laboratory results were also taken into account. The prevalence was adjusted to the sex and age structure of the Navarra population.

RESULTS

The study included a total of 7,378 patients with a median age 46 years, of whom 50% women. HCV antibodies were detected in 69 patients, which is a prevalence in the population of 0.83% (95% confidence interval: 0.64-1.05), and was higher in men (1.11%) than in women (0.56%; P=.0102). Among the HCV positive patients, 67 (97%) had had another previous positive result. Population prevalence of previous positive HCV was 0.80%, and was 0.03% for a new diagnosis. Of the HCV positive patients, 78% had detectable HCV-RNA. It was estimated that 0.65% of the population had had detectable HCV-RNA, and 0.51% continued to have it when recruited into the study.

CONCLUSION

Previous estimates of prevalence of HCV infection should be revised downwards. Only a small proportion of HCV positive patients remain undiagnosed, and only a small part have active infection.