Efficacy of light chain 3-fused protein multi epitope in protection of mice challenged with Mycobacterium tuberculosis

The new strategy for vaccine development such as the fused protein multi-epitope capable of preventing the reactivation of latent tuberculosis infection (LTBi) can be an effective strategy for controlling tuberculosis (TB) worldwide. This study was conducted to evaluate the immunity of experimentally infected BALB/c mice with Mycobacterium tuberculosis after injection of DNA construct. Nineteen female BALB/c mice were divided into three groups and injected with 0.50 mL of M. tuberculosis. After 3 weeks, lung and spleen samples from the infected mice were examined. The protective effects of light chain 3-fused protein multi-epitope against TB were evaluated for post-exposure and therapeutic exposure. The lungs and spleens of the mice were aseptically removed after death for histopathology analysis. The bacterial colonies were counted, and the cells were stained after 3 weeks of incubation. No significant differences were observed between the post-exposure and therapeutic exposure groups. The pathological changes in the lung tissue of mice in these groups included an increase in the thickness of interalveolar septa, hyperemia, and intraparenchymal pulmonary hemorrhage centers (positive control), scattered hyperemic areas (negative control), and hyperemia in the interstitial tissue, scattered hyperemic areas in the lung parenchyma and lymphocytic infiltration centers (experimental group). Flow cytometry of the post-exposure and therapeutic exposure models showed insignificant changes in all three groups. It seems necessary to develop a post-exposure and therapeutic exposure vaccine strategy that focuses on LTBi to prevent the progression of the active disease. In this regard, multi-epitope vaccines should be designed to induce both cellular and humoral immunity.

First Report of Massive Myocardial Calcifications in a Vervet Monkey (Chlorocebus pygerythrus)

A 13-years-old male vervet monkey that was kept in a primates breeding and research facility at Razi Vaccine and Serum Research Institute, Karaj, Iran (RVSRI) died suddenly. Massively scattered grayish-yellow mottling on both ventricles were the most significant gross necropsy findings. There was a gritty feeling on palpation and sectioning of the yellow areas. Microscopically, the lesions demonstrated scattered degeneration and necrosis of myocardial cells. Inside the affected areas, large calcium deposit plaques were detected using the Von kossa staining method. The development of myocardial calcification in the present case can be attributed to the dystrophic calcification following spontaneous myocardial necrosis or an undetected infection/inflammatory process. Persistent anxiety might trigger spontaneous biventricular necrosis in vervet monkeys. In conclusion, due to similarities between the clinical and histological presentation of the current case with sudden death syndrome associated with myocardial calcification in humans, it was suggested that vervet monkeys might be a relevant animal model for research on the pathophysiological processes of this complication.

Safety and Efficacy of Combined Intramuscular/Intranasal RAZI-COV PARS Vaccine Candidate Against SARS-CoV-2: A Preclinical Study in Several Animal Models

Several vaccine candidates for COVID-19 have been developed, and few vaccines received emergency approval with an acceptable level of efficacy and safety. We herein report the development of the first recombinant protein-based vaccine in Iran based on the recombinant SARS-CoV-2 spike protein in its monomeric (encompassing amino acid 1-674 for S1 and 685-1211 for S2 subunits) and trimer form (S-Trimer) formulated in the oil-in-water adjuvant system RAS-01 (Razi Adjuvant System-01). The safety and immunity of the candidate vaccine, referred to as RAZI-COV PARS, were evaluated in Syrian hamster, BALB/c mice, Pirbright guinea pig, and New Zeeland white (NZW) rabbit. All vaccinated animals received two intramuscular (IM) and one intranasal (IN) candidate vaccine at 3-week intervals (days 0, 21, and 51). The challenge study was performed intranasally with 5×106 pfu of SARS-CoV-2 35 days post-vaccination. None of the vaccinated mice, hamsters, guinea pigs, or rabbits showed any changes in general clinical observations; body weight and food intake, clinical indicators, hematology examination, blood chemistry, and pathological examination of vital organs. Safety of vaccine after the administration of single and repeated dose was also established. Three different doses of candidate vaccine stimulated remarkable titers of neutralizing antibodies, S1, Receptor-Binding Domain (RBD), and N-terminal domain (NTD) specific IgG antibodies as well as IgA antibodies compared to placebo and control groups (P<0.01). Middle and high doses of RAZI-COV PARS vaccine significantly induced a robust and quick immune response from the third-week post-immunization. Histopathological studies on vaccinated hamsters showed that the challenge with SARS-CoV-2 did not induce any modifications in the lungs. The protection of the hamster was documented by the absence of lung pathology, the decreased virus load in the lung, rapid clearance of the virus from the lung, and strong humoral and cellular immune response. These findings confirm the immunogenicity and efficacy of the RAZI-COV PARS vaccine. Of the three tested vaccine regimens, the middle dose of the vaccine showed the best protective immune parameters. This vaccine with heterologous prime-boost vaccination method can be a good candidate to control the viral infection and its spread by stimulating central and mucosal immunity.

Outbreak of avian mycobacteriosis in a commercial turkey breeder flock

Avian mycobacteriosis (AM) is a chronic and contagious disease of pet birds, captive exotic, wild and domestic fowl, and mammals. Mycobacterium avium subsp. avium is the most common cause of AM in poultry. For the first time, we report a chronic outbreak of AM in an Iranian breeder flock of 250 45-week-old turkeys (Meleagris gallopavo) with a morbidity and mortality rate of 91.6% and 80%, respectively. A well-defined clinical feature of the outbreak included a progressive weight loss, decreased egg production, listlessness, and lameness. Tuberculous nodules were seen on liver, spleen, ovary, and ribs. Granulomatous inflammation and acid-fast bacilli were confirmed by using Ziehl-Neelsen method on hepatic lesions. M. avium subsp. avium was identified by polymerase chain reaction techniques based on the presence of 16S ribosomal RNA gene and insertion elements IS1245 and IS901. In this report, we not only describe the epidemiological, pathological, and molecular characteristics of the outbreak in detail, but we also discuss multiple factors influencing the introduction and development of AM critically. In this case, wild feral pigeons might have been the source of infection, but further molecular-epidemiology studies are needed to understand the role of wild birds in the persistence and transmission of Mycobacterium.RESEARCH HIGHLIGHTS First report of avian mycobacteriosis in an Iranian commercial turkey flock is described in detail.Risk factors intrinsic to the bird and mycobacteria, as well as extrinsic factors influencing the introduction and development of avian mycobacteriosis in birds, are critically discussed.

Evaluation of tuberculin skin test (TST) in vervet monkeys (Chlorocebus pygerythrus) using experimentally tuberculin sensitized animals

BACKGROUND

Nowadays, several test methods with different useful values are available for diagnosis of the tuberculosis (TB) in non-human primates (NHPs). Despite some limitations of tuberculin skin test (TST), it is still the most commonly used method for TB testing of NHPs.

METHODS

During this investigation, TST was performed upon three groups of experimentally tuberculin sensitized and one group of non-sensitized vervet monkeys (Chlorocebus pygerythrus) by means of two types of old tuberculin (OT) and two types of purified protein derivative (PPD) tuberculin.

RESULTS

The data obtained from this study revealed that PPD tuberculin prepared from both Mycobacterium tuberculosis and Mycobacterium bovis has more advantages over OT in tuberculin testing of the vervet monkeys. The potency of the PPD tuberculin prepared from M bovis was estimated almost twice as much of the M tuberculosis.

CONCLUSIONS

Intrapalpebral injection of 0.1 mL of a concentration of ≥1 mg/mL of PPD tuberculin prepared from M bovis is the preferred method for TST of vervet monkeys.

Plasma Paraoxonase, Sphingosine-1-phosphate, Total Sialic Acid, and Heat Shock Protein-27 in the Liver of the Sheep Naturally Infected with Cysticercus Tenuicollis: Evidence on Pathological Changes

The present study aimed to investigate whether sphingosine 1 phosphate (S1P), paraoxonase (PON), total sialic acid (TSA), and heat shock protein-27 (HSP27) are altered in the sheep during infection of the liver with Cysticercus tenuicollis. This study was conducted on40 healthy sheep and40 sheep with Cysticercus tenuicollis infection. The infected and non-infected animals were selected based on the observation of severe Cysticercus tenuicollis infection in the liver and absence of any hepatic cysts, respectively. All parameters were measured in serum and plasma. The results revealed a significant decrease (P&amp;lt;0.01) in PON, TSA, and albumin (Alb) in the infected group, compared with those in the healthy one. Furthermore, the infected sheep had a significant increase (P&amp;lt;0.01) in S1P, HSP-27, malondialdehyde (MDA), total bilirubin, and unconjugated bilirubin as compared with those in their non-infected counterparts. Moreover, no significant change was observed in total plasma protein level in the infected animals in comparison to that in the healthy ones. The low levels of TSA and Alb revealed liver damage in the infected sheep. Moreover, the PON reduction might have resulted from hepatic steatosis and MDA enhancement. Meanwhile, S1P elevation could be attributed to the activation of platelets. In addition, HSP-27 increase was ascribed to the disease-induced stress conditions.