Asian Pacific Journal of Tropical Medicine

Number 14(7), 2021

287-298
Effect of short- and long-term immunization of recombinant disorganized muscle protein-1 (rDIM-1) against human filarial parasite Brugia malayi in rodents

Authors: Vikas Kushwaha, Puvvada Kalpana Murthy

Abstract

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Objective: To evaluate the effect of short-term and long-term immunization of recombinant disorganized muscle protein-1 (rDIM-1) in rodents against human filarial parasite Brugia malayi. Methods: Recombinant Brugia malayi DIM-1 (rDIM-1bm) protein was cloned, expressed and purified using a Ni-NTA affinity column. Mastomys coucha were immunized with rDIM-1bm in three immunization schedules: short-term (3-dose of rDIM-1bm), and long-term (booster doses till 3- and 6-week) and subsequently challenged with infective third-stage larvae of filarial parasite Brugia malayi (L3). Microfilaraemia was monitored in L3 exposed groups on day 90 post larval inoculation (p.l.i.) and continued till day 205 p.l.i. On day 205 p.l.i. all the infected animals were killed and total worm burden was estimated. Cellular proliferative response, macrophage activity, nitric oxide (NO) release, specific IgG and its subtypes, IgE, IgA and Th1 (IFN-γ, TNF-ααand IL-2) and Th2 (IL-4, IL-5, IL-6, IL-10 and IL-13) cytokine release were determined. Results: Of the 3 different immunization schedules, short term immunization (3-dose schedule) showed better reduction in microfilarial burden (36%-63%) in the peripheral circulation, adult worm load (52%), whereas long-term immunization (3- and 6-week schedule) exerted less effect on peripheral microfilariae count (9%-58%), and adult worm burden (9%-12.5%). Short-term immunization resulted in upregulation of cellular proliferation, macrophages activity, NO release, specific IgG, IgG1, IgG2a, IgG2b, IgE and IgA levels and both Th1 (IFN-γ, TNF-α and IL-2) and Th2 (IL-4, IL-5, IL-6, IL-10 and IL-13) cytokine release whereas long-term immunization (3- and 6-week schedule) exerted less effect on parasite burden and showed mixed immunological responses. None of the rDIM-1bm administration schedules induced any pathology in lymphoid tissues, or alteration in mast cell number and granularity. Conclusions: The short-term immunization with rDIM-1bm (3-dose schedule) induces robust immune responses and protects the host from filarial parasite infection.

299-308
Plasmid DNA encoding neutralizing human monoclonal antibody without enhancing activity protects against dengue virus infection in mice

Authors: Surachet Benjathummarak, Atsushi Yamanaka, Thanyaluk Krasae, Chonlatip Pipattanaboon, Subenya Injampa, Pannamthip Pitaksajjakul, Pongrama Ramasoota

Abstract

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Objective: To evaluate the expression of DNA plasmid-harboring modified antibody gene that produces neutralizing human monoclonal antibodies against four serotypes of dengue virus (DENV) without enhancing activity in BALB/c mice. Methods: We constructed pFUSE-based vectors (pFUSE_1G7C2_ hVH and pFUSE_1G7C2_hVL) containing genes encoding the variable domains of the heavy or light chain of the anti-dengue virus antibody 1G7C2, a human IgG1 that has been characterized for its neutralizing activity to DENV-1-4. Leucine (L) at positions 234 and 235 on the Fc CH2 domain in pFUSE_1G7C2_hVH was mutated to alanine (A) (LALA mutation) by site direct mutagenesis, and the new plasmid was termed pFUSE_1G7C2_hVH_LALA. An equal amount of pFUSE_1G7C2_hVL and 1G7C2_hG1-LALA plasmids were co-transfected into Chinese hamster ovary cells (CHO-K1) and a single dose of 100 µg 1G7C2_hG1-LALA plasmid was intramuscularly injected, followed by electroporation in BALB/c mice. The secreted 1G7C2_hG1-LALA antibodies in cell culture supernatant and mouse serum were examined for their biological functions, neutralization and enhancing activity. Results: The co-transfection of heavy- and light-chain 1G7C2_ hG1-LALA plasmids in CHO-K1 cells produced approximately 3 900 ng/mL human IgG and neutralized 90%-100% all four DENV, with no enhancing activity. Furthermore, the modified human IgG was produced more than 1 000 ng/mL in mouse serum on day 7 post plasmid injection and showed cross-neutralization to four DENV serotypes. Subsequently, antibody production and neutralization decreased rapidly. Nevertheless, the secreted neutralizing 1G7C2_ hG1-LALA in mouse serum demonstrated complete absence of enhancing activities to all DENV serotypes. Conclusions: These findings reveal that a new modified 1G7C2_ hG1-LALA expressing plasmid based on gene transfer is a possible therapeutic antibody candidate against DENV infection.

309-305
Spatio-temporal history of H9N2 viruses in Iran and neighbor countries by Bayesian analysis and molecular characterization

Authors: Nima Ghalekhani, Saied Bokaie, Sana Eybpoosh, Hesameddin Akbarein

Abstract

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Objective: To delineate the H9N2 influenza virus circulation within Iran and its neighboring countries, the potential source of the epidemic in these countries, and its date of origin. Methods: We obtained all hemagglutinin (HA) and neuraminidase (NA) nucleotide sequences of influenza H9N2 available up to December 25, 2020 from Iran and its neighboring countries (i.e., Pakistan, Afghanistan, Turkmenistan, Armenia, Azerbaijan, Turkey, and Iraq). We also performed a Bayesian Markov chain Monte Carlo method to infer the evolutionary dynamic and the most recent common ancestor for the HA and NA sequences. Results: H9N2 epidemic may have started in Iran and Pakistan much earlier than the other investigated countries in the region, and an ongoing bidirectional dispersion of the virus between the investigated countries was also observed. The mean time of the most recent common ancestor of H9N2 viruses was 1988 for HA, and 1992 for NA. Conclusions: Strains from investigated countries rooted in Pakistan and Iran. Regular surveillance of H9N2 viruses, especially in the live bird markets, enhancing the biosecurity of poultry industry and screening newly arriving immigrants and tourists from neighboring countries at border should be considered to control spread of the virus. Furthermore, surveillance of viral molecular evolution should be initiated for effective prevention of epidemic and pandemic spreads.

316-322
Antibacterial resistance patterns of Acinetobacter baumannii complex: The results of Isfahan Antimicrobial Resistance Surveillance-1 Program

Authors: Sayed Nassereddin Mostafavi, Soodabeh Rostami, Zary Nokhodian, Behrooz Ataei, Azam Cheraghi, Parisa Ataabadi, Naser Almasi, Zohreh Norouzi, Roya Kelishadi

Abstract

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Objective: To determine the antibiotic resistance patterns of the Acinetobacter (A.) baumannii complex isolates that cause the confirmed infection. Methods: The present descriptive study was performed from March 2016 to March 2018 in three referral hospitals in Isfahan, Iran. All A. baumannii complex strains isolated from different clinical samples were identified by conventional phenotypic methods and antibiotic susceptibility pattern was detected. After the clinical investigation, contaminated samples were excluded and the source (hospital/ community) and site of the infection were determined. Data on antibiotic susceptibility testing were extracted from WHONET software and analysis was done with SPSS. Results: From 254 patients who had confirmed A. baumannii complex infection, 158 (62.20%) cases were male, 27 (10.63%) were less than 20 years old, 172 (67.72%) had healthcare-associated infections and 96 (37.79%) were admitted in intensive care units. The most frequent infection was bloodstream infections (111, 43.70%). Our results showed that most of the isolates were resistant to most of the antibiotics (more than 75.00%) and a lower rate of non-susceptibility was observed against minocycline (20, 44.44%) and colistin (0%). The rate of multidrug-resistant isolates was 88.97%. There was no significant difference between resistance of A. baumannii complex isolates according to age. However, the resistance to amikacin and minocycline and the rate of multidrug resistance (MDR) were significantly different between males and females. In patients with healthcare associated infection (HAI), MDR isolates were significantly different regarding admission in ICU ward. Resistance to levofloxacin and ciprofloxacin were lower in isolates from patients with bloodstream infections in comparison to other diagnoses. Conclusions: In our study, a high level of antibiotic resistance was detected in both community-acquired and healthcare-associated A. baumannii complex infections. Appropriate antibiotic prescription in a clinical setting is an essential need for the control and prevention of A. baumannii resistant infections.

323-329
Phylogeny of Brucella abortus strains isolated in the Russian Federation

Authors: Dmitry A. Kovalev, Dmitriy G. Ponomarenko, Sergey V. Pisarenko, Nikolay A. Shapakov, Anna A. Khachaturova, Natalia S. Serdyuk, Olga V. Bobrysheva, Alexander N. Kulichenko

Abstract

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Objective: To study Brucella (B.) abortus strains isolated in the Russian Federation, in order to identify their detailed position in the phylogenetic structure of the species global population as well as to determine genetic relationships for isolates from different geographical areas. Methods: Based on Bayesian method, the whole genome single nucleotide polymorphism (SNP) analysis of 258 B. abortus strains from different geographical areas of the world including 20 B. abortus strains isolated in Russia was carried out. Results: The core genome SNP analysis of the B. abortus isolates allowed describing the main genetic lineages. The Russian strains entered two separate clades, including the basal branch and the C1 branch that is widely spread in Eurasia. The data on the isolation time was used for the dating of phylogenetic tree, and also the estimated time frame for the B. abortus genotype diversification was determined. There were sets of specific SNPs identified, which defined each of the genotypes and sub-genotypes. Conclusions: A significant genetic diversity of the brucellosis pathogen strains from Russia has been proven. The sets of unique specific SNPs described in our study may become one of the elements within a bio-informational analysis algorithm to be used for epidemiological study of brucellosis outbreaks, including those caused by new (atypical) genetic variants of B. abortus.

330-332
ACE2 downregulation promotes thrombosis and cardiac injury in COVID-19 patients

Authors: Dhanasekaran Sivaraman, Kagithakara Vajravelu Leela, Venkatesalu Venugopal

Abstract

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Number of views: 123

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