Molecular crowding accelerates aggregation of α-synuclein by altering its folding pathway.

Intracellular macromolecular crowding can lead to increased aggregation of proteins, especially those that lack a natively folded conformation. Crowding may also be mimicked by the addition of polymers like polyethylene glycol (PEG) in vitro. α-Synuclein is an intrinsically disordered protein that exhibits increased aggregation and amyloid fibril formation in a crowded environment. Two hypotheses have been proposed to explain this observation. One is the excluded volume effect positing that reduced water activity in a crowded environment leads to increased effective protein concentration, promoting aggregation. An alternate explanation is that increased crowding facilitates conversion to a non-native form increasing the rate of aggregation. In this work, we have segregated these two hypotheses to investigate which one is operating. We show that mere increase in concentration of α-synuclein is not enough to induce aggregation and consequent fibrillation. In vitro, we find a complex relationship between PEG concentrations and aggregation, in which smaller PEGs delay fibrillation; while, larger ones promote fibril nucleation. In turn, while PEG600 did not increase the rate of aggregation, PEG1000 did and PEG4000 and PEG12000 slowed it but led to a higher overall fibril burden in the latter to cases. In cells, PEG4000 reduces the aggregation of α-synuclein but in a way specific to the cellular environment/due to cellular factors. The aggregation of the similarly sized, globular lysozyme does not increase in vitro when at the same concentrations with either PEG8000 or PEG12000. Thus, natively disordered α-synuclein undergoes a conformational transition in specific types of crowded environment, forming an aggregation-prone conformer.

Experimental study of dengue virus infection in Aedes aegypti and Aedes albopictus: A comparative analysis on susceptibility, virus transmission and reproductive success.

Epidemiology of dengue fever has substantially changed over the years with respect to prevalent strains, affected geographical locations and severity of disease. Mosquito vectors show variable response in terms of susceptibility to four different serotypes of dengue virus. Although studies have postulated that, the vectors Ae. aegypti and Ae. albopictus are crucial for transmission of dengue virus, comparative efficacy of these species for viral transmission and tolerance is still enigmatic. In this study, these two vectors were infected orally with four serotypes of the dengue virus viz. DENV-1 to DENV-4 and their co-infection. It was observed that Ae. aegypti harbors multiple serotype infections more efficiently than Ae. albopictus. We suggest that transovarial transmission is of low importance in the epidemiology of the virus due to low infection rates in the filial generation, and also that reduced fecundity and fertility in both vectors after dengue virus infection affect the ecology of the pathogen.

Dengue outbreak in a hilly state of Arunachal Pradesh in Northeast India.

Dengue has been reported from plains as well as hilly regions of India including some parts of Northeast India. In July-August 2012, outbreak of fever with unknown origin (FUO) indicative of Dengue was reported in Pasighat, East Siang district of Arunachal Pradesh (AP) state. Serum samples (n = 164) collected from patients from Health Training and Research Centre General Hospital, Pasighat, were tested for NS1 antigen and IgM antibodies. NS1-positive samples were analyzed by RT-PCR assay and entomological surveys were carried out. The majority of suspected cases reported NS1 antigen positivity. Females and young adults were mostly affected. The majority of the amplified NS1-positive samples showed Dengue serotype 3 infection. Aedes (Stegomyia) albopictus, known as semiurban breeding mosquitoes, was the only potential vector species identified from the affected areas of Pasighat which single handedly contributed to the outbreak. Thus, the present work identifies Dengue as an emerging arboviral infection in hilly state of AP along with a looming risk of its spread to neighbouring areas.

Detection of point mutation in Plasmodium falciparum ATPase6 gene associated with artemisinin resistance from Assam and Arunachal Pradesh.

BACKGROUND & OBJECTIVES: Resistance against partner drugs of artemisinin has been reported from different parts of India. The study aims to find out the single nucleotide polymorphisms in Plasmodium falciparum ATPase6 gene associated with artemisinin resistance. METHODS: Blood samples were collected from 141 patients with P. falciparum monoinfection in malaria endemic zones of Assam and Arunachal Pradesh. A 645 bp portion of PfATPase6 gene was amplified and sequenced to determine the frequency of mutations associated with resistance to artemisinin. RESULTS: Mutations at codon S769N, which have been proposed to confer artemisinin resistance, were not detected in our study samples. Instead of that a novel non-synonymous mutation (C-T) at 1847 bp position resulting in serine to phenylalanine alteration at codon S616F was detected from the P. falciparum field isolates in Changlang district of Arunachal Pradesh, whereas no mutation was detected in any of the analyzed samples in Assam indicating that wild type PfATPase6 genotype was found circulating in this region. Overall, based on the mutational pattern, two haplotypes of PfATPase6 gene were observed during the study, the wild type and mutant S616F allele. The overall haplotype diversity (Hd) was found to be: 0.069 and nucleotide diversity (per site Pi): 0.00012. Highest haplotype diversity was recorded in Changlang district of Arunachal Pradesh having Hd value of 0.33333 along with single polymorphic site and nucleotide diversity (Pi): 0.00060. A pair-wise fixation index (FST) value of 0.16667 indicates great genetic differentiation within the parasite population of Changlang district with the population of Karbi Anglong, Chirang, Tinsukia, Sivasagar, Jorhat, NC Hills, Lakhimpur, Golaghat and Dibrugarh districts of Assam and Lohit district of Arunachal Pradesh. INTERPRETATION & CONCLUSION: A better understanding of the distribution of antimalarial drug resistance with malaria parasite may provide insight into some of the epidemiological determinants of the increasing case burden.

Scrub typhus in Northeast India: epidemiology, clinical presentations, and diagnostic approaches.

Scrub typhus is one of the most neglected tropical diseases, a leading cause of acute undifferentiated febrile illness in areas of the 'tsutsugamushi triangle', diagnosed frequently in South Asian countries. The bacteria Orientia tsutsugamushi is the causative agent of the disease, which enters the human body through the bite of trombiculid mites (also known as chiggers) of the genus Leptotrombidium deliense. Diagnosis of the disease is challenging, as its early symptoms mimic other febrile illnesses like dengue, influenza and corona viruses. Lack of rapid, reliable and cost-effective diagnostic methods further complicates the identification process. Northeast India, a mountainous region with a predominantly rural tribal population, has witnessed a resurgence of scrub typhus cases in recent years. Various ecological factors, including rodent populations, habitat characteristics and climatic conditions, influence its prevalence. Entomological investigations have confirmed the abundance of vector mites, highlighting the importance of understanding their distribution and the probability of transmission of scrub typhus in the region. Proper diagnosis, awareness campaigns and behavioural interventions are essential for controlling scrub typhus outbreaks and reducing its impact on public health in Northeast India. Further research and community-based studies are necessary to accurately assess the disease burden and implement effective prevention strategies.

Serological and molecular prevalence of Brucella spp. among livestock species in Rajasthan, India.

A seroprevalence and molecular study was carried out in six districts of the state of Rajasthan, India to detect brucellosis in major livestock species. This study involves the testing of 3,245 livestock samples using the Rose Bengal Plate Test (RBPT), Indirect Enzyme-Linked Immunosorbent Assay (i-ELISA), and genus-specific polymerase chain reaction (PCR) markers for molecular diagnosis of the disease. In the tested samples, seroprevalence was 5.06% (CI: 1.96-8.15) using the RBPT test and 6.88% (CI: 1.98-11.78) using the i-ELISA test, while the cumulative seroprevalence (RBPT and i-ELISA) was 3.63% (CI: 0.44-6.83). The prevalence of the disease was 1.27% (CI: 0.56-3.11) when tested using molecular markers. The highest prevalence of brucellosis was detected in Cattle (7.00, 3.22%), followed by camels (5.50, 2.50%), buffalo (2.66, 0.00%), sheep (2.43, 0.41%), and goats (0.58, 0.23%) when serological (cumulative) and molecular diagnosis were considered preferred methods of detection. Cattle (3.22%) and camels (2.50%) also showed a high prevalence of disease when tested using molecular markers. The results of this study reveal that cattle, camel, and sheep brucellosis is prevalent in the study areas.

Corrigendum: Serological and molecular prevalence of Brucella spp. among livestock species in Rajasthan, India.

[This corrects the article DOI: 10.3389/fvets.2023.1157211.].

Bioassay and molecular study for detection of insecticide resistance dengue causing mosquito vectors.

Nowadays, dengue infection creates a major problem across the country. The vector species carrying dengue infection has progressively started to developed resistance against most of the currently used insecticides. Hence, a study was carried out in dengue-endemic areas of Assam and Arunachal Pradesh to find the current situation of insecticide susceptibility status of dengue vectors. Based on the previous history of dengue incidence, Aedes mosquitoes were collected from Dibrugarh, Kamrup, Sivasagar, Tezpur and Tinsukia districts in Assam and Pasighat district in Arunachal Pradesh to test the insecticide resistance status through bioassay and molecular methods. The WHO standard bioassay test kits were used to detect insecticide susceptibility status among dengue vectors. In molecular study, allele-specific polymerase chain reaction (PCR) method was done for the detection of mutations in paratype voltage-gated sodium channel gene of Aedes aegypti and Aedes albopictus mosquitoes. In bioassay method, 100% A. aegypti mosquitoes were found to be resistant towards dichlorodiphenyltrichloroethane (DDT), 8% towards pyrethroid and 4% towards malathion. Similarly, 92% A. albopictus mosquitoes have shown resistance competency towards DDT, 12% towards pyrethroid and 8% towards malathion. In allele-specific PCR methods, V1016G heterozygous mutations were detected from the field collected A. aegypti and A. albopictus mosquitoes of Tinsukia, Dibrugarh and Sivasagar district. Similarly, F1534C heterozygous mutations were observed from A. aegypti mosquitoes of Tezpur, Tinsukia and Sivasagar district and A. albopictus mosquitoes of Tinsukia, Dibrugarh and Sivasagar district. From the study, it was concluded that the Aedes mosquitoes have progressively started to developed resistance towards commonly used insecticides.

Review on transovarial transmission potentiality of dengue vectors: An international perspective with special reference to North-Eastern region of India.

Despite extensive research in vaccine development, there is at present no known method of controlling dengue except by the mosquito vectors. Virologic surveillance which involves the detection of dengue virus (DENV) in human serum and followed by isolation of virus using cell culture or mosquito inoculation is used as an early warning symptom to predict the outbreak. The technique is not much effective as the virus is in the human population. However, if the virus is detected in mosquito before it can infect humans could be more effective approach. One of the great mysteries about the epidemiology of dengue is how the virus persists in the interepidemic period. So far, no such studies on dengue vectors have been conducted in the north-eastern region of India, especially in Assam and the dengue cases are increasing every year. There are no reports on the identification of active and potential role of dengue vector responsible for the transmission of dengue in this state. Such type of study will give an overall picture of potential dengue vector responsible for human DENV infection and the viral load carried by the mosquito species in different generations. Such study will be useful in helping the public health personnel.

Prevalence of multiple drug-resistant Plasmodium falciparum malaria cases in Northeast India.

Two numbers of Plasmodium falciparum field isolates from Gossingpara, Runikhata area in Chirang district of Assam had shown multiple mutations in Pfcrt-dhfr-dhps gene (up to seven mutations: One mutation in Pfcrt gene, three mutations in Pfdhfr gene and three mutations in Pfdhps gene). Similarly, two cases in Bat camp, Miao area under Changlang district of Arunachal Pradesh had shown a total of eight mutations, of which one mutation in Pfcrt gene, three mutations in Pfdhfr gene, three mutations in Pfdhps gene and one mutation in PfATPase6 gene. One case in 3 Miles, Miao area of Changlang district has shown mutations in Pfcrt(one mutation), Pfdhfr(four mutations) and Pfdhps(three mutations) gene. These results indicated that there is an existence of multiple mutant P. falciparum malaria cases in northeastern region of India.

Molecular typing and phylogeny of Wolbachia: A study from Assam, North-Eastern part of India.

BACKGROUND: Wolbachia are maternally inherited endosymbiotic alphaproteobacteria, infecting 40-75% of arthropod species. Knowledge on distribution of native strains infecting mosquito vectors from endemic regions is essential for successful implementation of vector control interventions utilizing potential strains of Wolbachia. Study identified various native strains of Wolbachia inhabiting different mosquito species from field and colonised conditions of Assam. The fly Drosophila melanogaster was also included in our study. METHODS: Different mosquito species collected from field viz; Aedes albopictus, Aedes aegypti, Anopheles hyrcanus, Anopheles annularis, Culex vishnui, Toxorhynchites splendens, Armegeries obturbans and fly Drosophila melanogaster were included in the study. Anopheles stephensi and Culex quinquefasciatus were obtained from RMRC, Dibrugarh mosquito colony y for Wolbachia screening. DNA was extracted from these species, amplified using group specific wsp primers followed by sequencing and phylogenetic analysis. RESULTS: Aedes albopictus from Dibrugarh, Tinsukia and Sivasagar district showed superinfection with A and B group of Wolbachia but, Aedes albopictus from Tezpur district presented infection with A group only. Our study reports for the first time natural infection of Wolbachia A and B group from colonised Anopheles stephensi mosquito but reported no infection from field collected Anopheles hyrcanus or Anopheles annularis. Similarly Armigeres obturbans and Culex vishnui presented infection with only B group of Wolbachia. Drosophila melanogaster showed superinfection with A and B group. Toxorhynchites splendens, Aedes aegypti and Culex quinquefasciatus reported no infection with Wolbachia. CONCLUSION: To the best of our knowledge this is the first study on Wolbachia screening from Northeast part of India and also first report of natural Wolbachia infection from colonised Anopheles stephensi species. The current understanding on distribution of Wolbachia strains naturally present within insect species from this geographical region should aid future Wolbachia mediated vector control strategies.

Synthesis, structural, and biological studies of some schiff bases and their metal complexes.

New bidentate or tridentate Schiff bases and their VO(II) and Co(II) complexes formed by the condensation of methyl isobutyl ketone with nicotinamide (mna)/2-amino-4-chlorophenol (map) and 2-hydroxy acetophenone with nicotinamide (han)/isoniazide (hai). Physicochemical characterization has been carried out to determine the structure of the complexes. The FAB mass and thermal data show degradation pattern of the complexes. XRD analysis reveals that all the studied complexes crystallize as tetragonal crystal system. Some of the complexes have been screened for their antimicrobial activity by the well diffusion technique using DMSO as solvent on different species of pathogenic bacteria/fungi, that is, E. coli, S. aureus, S. fecalis, A. niger, T. polysporum, and their antimicrobial potency have been discussed. It has been found that all the complexes are antimicrobially active and show higher activity than the free ligand. Metal chelation affects significantly the antimicrobial/bioactive behavior of the organic ligands.