Flavivirus cross-reactivity in serological tests and Guillain-Barré syndrome in a hematopoietic stem cell transplant patient: A case report.

Serological diagnosis of flavivirus infection is a challenge, particularly in the context of a disease associated with immune response enhancement in a transplant patient, where aspects such as previous flavivirus infections may be involved with the outcome. We report a case of a pediatric patient who developed Guillain-Barré syndrome (GBS) after matched-unrelated hematopoietic stem cell transplantation (HSCT). The patient lives in a Brazilian region that is experiencing an epidemic of Zika virus (ZIKV) and dengue virus (DENV). Because an increasing number of cases of GBS, likely triggered by ZIKV infection, are being reported in Brazil, samples from the patient were tested for both ZIKV and DENV infection. Serological assays strongly suggested a recent ZIKV infection, although infection by DENV or co-infection with both viruses cannot be ruled out. The presence of anti-DENV immunoglobulin-G in donor serum led to the hypothesis that antibodies from the donor could have enhanced the severity of the ZIKV infection. This hypothesis is in agreement with the recent findings that DENV sero-cross-reactivity drives antibody-dependent enhancement of ZIKV infection. These findings highlight the need for discussion of the indication to perform previous flavivirus tests in HSCT donors, especially in areas where ZIKV and other flaviviruses co-circulate.

Prevalence of myocardial infarction is related to hyperhomocysteinemia but not influenced by C677T methylenetetrahydrofolate reductase and A2756G methionine synthase polymorphisms in diabetic and non-diabetic subjects.

BACKGROUND: Hyperhomocysteinemia has emerged as a novel risk factor for myocardial infarction (MI). Some mechanisms proposed to explain its relationship with coronary events are also shared by major coronary risk factors. We examined whether C677T methylenetetrahydrofolate reductase and A2756G methionine synthase polymorphisms could affect the relative risk for MI. METHODS: A sample of 196 individuals was divided into four groups (diabetics with MI, n=43; diabetics without MI, n=50; non-diabetics with MI, n=47; non-diabetics without MI, n=56) and compared regarding the prevalence of the polymorphisms, risk factors, and biochemical parameters. RESULTS: Higher prevalence of hyperhomocysteinemia was found in MI patients (p<0.05 vs. non-MI subjects), in males (p<0.001 vs. female) and in those > or = 65 years (p=0.01 vs. <65 years). Homocysteine was negatively associated with HDL-C (p<0.05) and glucose, although results did not reach significance (p=0.06). Similar distribution of studied polymorphisms was seen in all groups, which presented normal folate and vitamin B12 serum levels. CONCLUSIONS: Higher homocysteinemia was predominantly observed in men, presenting low HDL-C, and at advancing age. Methylenetetrahydrofolate reductase and methionine synthase polymorphisms did not contribute to risk assessment in diabetic and non-diabetic subjects presenting normal folate levels.