Molecular targets for the development of new acaricides against Rhipicephalus microplus: a review

The cattle tick Rhipicephalus microplus is an ectoparasite with high economic importance to bovine culture, mainly in tropical and subtropical regions. The resistance of the tick from the commercial acaricides has hindered its control, thus motivating the search for new strategies. The purpose of this study was to perform a critical review about the main molecular targets of R. microplus that are useful for the discovery of new acaricides. Bibliographic search was conducted in the databases PubMed, ScienceDirect and CAB Direct, using the following descriptors: ‘Rhipicephalus microplus’, ‘Boophilus microplus’, ‘molecular targets’ and ‘action’, published between 2010 and 2021. Out of the 212 publications identified, 17 articles were selected for study inclusion. This review described 14 molecular targets and among these 4 are targets from commercial acaricides. Most of them are enzymes to catalyse important reactions to tick survival, related to energetic metabolism, mechanisms of biotransformation and neurotransmission. The data will be helpful in the development of new more effective and selective acaricides.

Levels of mannose-binding lectin in individuals with visceral leishmaniasis in the northeast region of Brazil

Visceral leishmaniasis (VL) is one of the seven priority endemic diseases in the world. The clinical outcome of many infections is not only dependent on the pathogenic organism, but also on the genetic variability of the host susceptibility to infection. Mannose-binding lectin (MBL) is a protein that plays an important role in the innate immune system. The aim of this study was to compare the serum levels of MBL between healthy controls and carriers of VL. The VL cases were recruited randomly from the main hospitals and referral outpatient clinics for VL in São Luís, and from home visits. Determination of MBL protein levels was performed by enzyme-linked immunosorbent assay. Of the 161 patients with VL and the 161 healthy controls, 60.9 and 67.1% had high levels of MBL, respectively. There was no significant difference in MBL levels between cases and controls. Low socioeconomic status and living conditions are conducive to the occurrence of VL. Owing to the small number of existing studies, it is extremely important to conduct further studies on MBL levels and susceptibility to VL, especially in regions where the disease is endemic, such as Maranhão, Brazil.

Screening for fragile X syndrome in males from specialized institutions in the northeast region of Brazil

The objective of this study was to perform a study of fragile X syndrome (FXS) in São Luís, Maranhão, in males residing in five specialized institutions. Two hundred thirty-eight males with intel-lectual disability of unknown etiology participated in this study. Blood samples were processed and stored until DNA extraction. Screening for FMR1 gene mutations was performed using non-isotopic polymerase chain reaction amplification and DNA sequencing using an ABI Prism 3130 automated sequencer. Two individuals (0.84%) were positive for FMR1 mutations. One had a mutation due to expansion of the CGG repeat beyond normal levels and the other had a deletion in exon 1 of the FMR1 gene, which was confirmed by sequencing. Both probands were over 18 years old, which demonstrates the late diagnosis of the condition in these individuals and reinforces the need to implement ef-fective programs for early diagnosis of FXS in the state of Maranhão. We found that FXS might be transmitted in the families of the two indi-viduals bearing the mutation, and that it is important to understand the mutation dynamics to provide better counseling to the family members of these two individuals.

Hepatitis Delta virus genotype 8 infection in Northeast Brazil: inheritance from African slaves?

Hepatitis Delta virus (HDV) is endemic worldwide, but its prevalence varies in different geographical areas. While in the Brazilian Amazon, HDV is known to be endemic and to represent a significant public health problem, few studies have assessed its prevalence in other regions in the country. This study evaluated the seroprevalence of HDV among HBsAg chronic carriers from Maranhão state, a region located in the Northeast of Brazil. Among 133 patients, 5 had anti-HD, of whom 3 had HDV RNA. HDV genotypes were characterized by Bayesian phylogenetic analysis of nucleotide sequences from the HDAg coding region. HDV-3 was identified in one patient who lives in Maranhão, but was born in Amazonas state (Western Amazon basin). Phylogenetic analysis shows that this HDV-3 sequence grouped with other HDV-3 sequences isolated in this state, which suggests that the patient probably contracted HDV infection there. Surprisingly, the other two patients were infected with HDV-8, an African genotype. These patients were born and have always lived in Urbano Santos, a rural county of Maranhão state, moreover they had never been to Africa and denied any contact with people from that continent. This is the first description of the HDV-8 in non-native African populations. This genotype may have been introduced to Brazil through the slaves brought to the country from the West Africa regions during the 16-18th centuries. Our results indicate that the need of clinical and epidemiological studies to investigate the presence of this infection in other areas in Brazil.