Development of New PCR Protocols to Detect Genetic Diversity in the Metronidazole Metabolism Genes in Susceptible and Refractory Clinical Samples of Giardia duodenalis

PURPOSE

Investigating the genetic variation in thioredoxin reductase (TrxR) and nitroreductase (NR) genes in both treatment-resistant and -sensitive Giardia duodenalis isolates can provide valuable information in identifying potential markers of resistance to metronidazole. The rapid increase in metronidazole treatment failures suggests the presence of genetic resistance mechanisms. By analyzing these genes, researchers can gain insights into the efficacy of metronidazole against G. duodenalis and potentially develop alternative treatment strategies. In this regard, four G. duodenalis isolates (two clinically sensitive and two clinically resistant to metronidazole) were collected from various hospitals of Shiraz, southwestern Iran.

METHODS

Parasitological methods including sucrose flotation and microscopy were employed for the primary confirmation of G. duodenalis cysts in stool samples. Microscopy-positive samples were approved by SSU-PCR amplification of the parasite DNA. All four positive G. duodenalis specimens at SSU-PCR were afterward analyzed utilizing designed primers based on important metronidazole metabolism genes including TrxR, NR1, and NR2.

RESULTS

Unlike TrxR gene, the results of NR1 and NR2 genes showed that there are non-synonymous variations between sequences of treatment-sensitive and -resistant samples compared to reference sequences. Furthermore, the outcomes of molecular docking revealed that there is an interaction between the protein sequence and spatial shape of treatment-resistant samples and metronidazole in the position of serine amino acid based on the NR1 gene.

CONCLUSION

This issue can be one of the possible factors involved in the resistance of Giardia parasites to metronidazole. To reach more accurate results, a large sample size along with simulation and advanced molecular dynamics investigations are needed.

Global prevalence and associated risk factors of diarrheagenic Giardia duodenalis in HIV/AIDS patients: A systematic review and meta-analysis

Giardia duodenalis is one of the leading causes of diarrhea, mostly in underdeveloped nations of Africa and Asia. The present review provides insights into the prevalence, odds ratios (ORs) and associated risk factors of giardiasis in HIV/AIDS patients. Four major English databases (Web of Science, PubMed, Scopus, and Google Scholar) were excavated for relevant literature without time limitation until 20 November 2020. Next, meta-analysis was performed using a random-effects model and 95% confidence intervals (CIs). As well, heterogeneity among studies was evaluated using Cochran's Q and the I²-statistic. Totally, 19,218 HIV/AIDS patients in 130 studies were examined, showing a 5% (95% CI: 4.2%-6%) pooled prevalence. Also, the weighted random-effects OR of G. duodenalis infection among HIV/AIDS patients in comparison with their controls in 48 case-control studies was estimated as 1.71% (95% CI: 1.1%-2.66%, p = 0.016). Based on sensitivity analysis, there was no remarkable variation in the pooled OR upon omitting individual studies. Diarrhea was a potent risk factor, since HIV/AIDS patients with diarrhea were 3.8-times (95% CI: 1.6-8.9, p = 0.002) more prone to G. duodenalis infection than those without diarrhea. Moreover, the prevalence of the parasitic infection was 1.2-times higher in patients without antiretroviral therapy (ART) than those with ART (p = 0.312). Meta-regression was employed to evaluate the possible association between G. duodenalis frequency in HIV/AIDS patients and some variables such as sample size, publication year, and HDI. Additionally, the pooled prevalence of G. duodenalis infection was estimated based on several subgroups, including publication years, WHO regions, countries, continents, country incomes, and CD4⁺ T-cell levels. Altogether, the epidemiology of giardiasis in HIV/AIDS patients and its association with various risk factors is still open to question and requires more detailed and comprehensive investigations.

Global epidemiology of Giardia duodenalis infection in cancer patients: a systematic review and meta-analysis

Background

Application of chemotherapeutics in cancer patients may provide an immunosuppressive milieu, favourable for parasitic infections. Giardia duodenalis is an important zoonotic intestinal parasite responsible for diarrhoea in humans worldwide.

Methods

The present systematic review and meta-analysis was conducted to estimate the prevalence of G. duodenalis and respective odds ratios (ORs) in cancer patients around the globe. Four online databases—PubMed, Scopus, Web of Science and Google Scholar—were carefully explored for relevant literature without time limitation until 28 November 2020. Meta-analysis was done based on a random effects model to pool the estimations and define 95% confidence intervals (CIs).

Results

The overall weighted prevalence of G. duodenalis infection in cancer patients was calculated to be 6.9% (95% CI 0.5 to 9.3) globally, based on data from 32 studies. Although not statistically significant, eight case–control studies revealed that cancer patients were 1.24 times (95% CI 0.66 to 2.31; p=0.501) more exposed to G. duodenalis infection than healthy controls. Moreover, the prevalence of infection was not significantly associated with quantitative variables, including publication year (regression coefficient −0.0135, p=0.578), sample size (regression coefficient −0.0007, p=0.074) and human development index (regression coefficient −1.6263, p=0.419). Also, subgroup analysis of the pooled G. duodenalis infection was performed for publication year, World Health Organization regions, countries, continents, cancer types and country income.

Conclusions

Altogether, the epidemiology of G. duodenalis infection and its associated risk factors in immunocompromised individuals, especially cancer patients, is still open to question and deserves comprehensive investigations.

Overview of the current promising approaches for the development of an effective severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine

Coronavirus disease 2019 (COVID-19) is a pandemic infectious disease caused by the novel coronavirus called SARS-CoV-2. There is a gap in our understanding regarding the immunopathogenesis of COVID-19. However, many clinical trials are underway across the world for screening effective drugs against COVID-19. Nevertheless, currently, no proven effective therapies for this virus exists. The vaccines are deemed as a significant part of disease prevention for emerging viral diseases, since, in several cases, other therapeutic choices are limited or non-existent, or that diseases result in such an accelerated clinical worsening that the efficacy of treatments is restricted. Therefore, effective vaccines against COVID-19 are urgently required to overcome the tremendous burden of mortality and morbidity correlated with SARS-CoV-2. In this review, we will describe the latest evidence regarding outstanding vaccine approaches and the challenges for vaccine production.

Coronavirus disease 2019 (COVID-19): Immunological approaches and emerging pharmacologic treatments

The SARS-CoV-2 virus is an etiological agent of pandemic COVID-19, which spreads rapidly worldwide. No proven effective therapies currently exist for this virus, and efforts to develop antiviral strategies for the treatment of COVID-19 are underway. The rapidly increasing understanding of SARS-CoV-2 virology provides a notable number of possible immunological procedures and drug targets. However, gaps remain in our understanding of the pathogenesis of COVID-19. In this review, we describe the latest information in the context of immunological approaches and emerging current antiviral strategies for COVID-19 treatment.

Expression of rice thaumatin-like protein gene in transgenic banana plants enhances resistance to fusarium wilt

The possibility of controlling Fusarium wilt--caused by Fusarium oxysporum sp. cubensec (race 4)--was investigated by genetic engineering of banana plants for constitutive expression of rice thaumatin-like protein (tlp) gene. Transgene was introduced to cauliflower-like bodies' cluster, induced from meristemic parts of male inflorescences, using particle bombardment with plasmid carrying a rice tlp gene driving by the CaMV 35S promoter. Hygromycin B was used as the selection reagent. The presence and integration of rice tlp gene in genomic DNA confirmed by PCR and Southern blot analyses. RT-PCR revealed the expression of transgene in leaf and root tissues in transformants. Bioassay of transgenic banana plants challenged with Fusarium wilt pathogen showed that expression of TLP enhanced resistance to F. oxysporum sp. cubensec (race 4) compared to control plants.