Serine protease activity demonstrated in the larval stage of the pentastomid Linguatula serrata

Prevalence and risk factors of Linguatula spp. in slaughter animals in Tabriz, Iran, and methods for nymphal stage inactivation

Linguatula is a food born zoonotic parasite in which carnivores and herbivores serve as final and intermediate hosts, respectively. Human infection with Linguatula spp. occurs following consumption of raw or undercooked infected internal organs of the intermediate host and/or consumption of water and/or vegetables contaminated with eggs released from final hosts. The aim of this study was to determine prevalence and risk factors of Linguatula spp. in sheep, cattle, buffalo, goats and camels slaughtered at the Tabriz abattoir, Iran. In addition, effect of temperature and sodium chloride (NaCl) on survival time of Linguatula spp. nymphs was assessed. For this purpose, 25,520 mesenteric lymph nodes from 2552 animals and the livers and lungs from 656 animals were collected randomly and examined. To evaluate the effect of temperature and NaCl on the survival of Linguatula spp. nymphs in infected livers and lungs, 30 g of each liver and lung with dimensions of 2 × 3 × 4 cm, were exposed to temperatures of -20, 10, 50, 60 and 72 °C and NaCl concentrations of 5 %, 10 %, 15 % and 20 % for 3, 6, 12, 24, 48 and 72 h, in triplicate. Based on the mesenteric lymph nodes, 25.7 % (656 of 2552 animals) were infected with Linguatula spp. Of the 656 liver and lungs assessed, 141 (21.5 %) and 62 (9.5 %) were infected with Linguatula spp., respectively. The rate of infection of mesenteric lymph nodes in all animals was significant with age (P < 0.05), with more older animals infected. In regards to sex, except for camels, more female animals were infected than male animals (P < 0.05). There was a significant difference in survival of nymphs based on temperature and/or NaCl and time (P < 0.0001). At 72 h, all temperatures assessed except 10 °C, resulted in all nymphs being inactivated. Sodium chloride was more effective against Linguatula spp. nymphs in livers than in lungs with 100 % efficacy only achieved against nymphs in livers at 20 % concentration after 48 h and at 10 and 15 % concentration after 72 h. Based on these results, heating and application of common salt as a food preservative in meat products reduces the survival time of Linguatula spp. nymphs and their use could decrease the risk of food-born microorganisms.

Linguatulosis in small ruminants in southeastern Iran: Epidemiological, histopathological and phylogenetic findings and its public health importance

Linguatulosis, as a zoonotic disease, can infect most ruminants and cause accidental infections in humans. The objective of this study was to explore the epidemiological, histopathological and phylogenetic profiles of Linguatula serrata infection in sheep and goats and its public health importance during 2015-2018. Mesenteric lymph nodes (MLNs) and liver tissue of goats and sheep were selected randomly in Kerman slaughterhouse. Nymphal samples were used for DNA extraction, amplification and subsequently phylogenetic analysis using 18s rRNA and cytochrome C oxidase subunit 1 (cox1). Overall, of 828 examined livestock, 179 (42.4%) goats and 71 (17.5%) sheep were found to be infected with the nymphal stage of L. serrata. A significant difference was observed between linguatulosis and age. In the histopathological assessment, longitudinal and transverse sections of L. serrata nymphs were observed within the cyst-like spaces surrounded by a wall of fine fibrosis and compact lymphocytes. Moreover, comparing with the L. serrata reference sequences, we found only a single nucleotide change in our goat haplotype in 18s genetic region; while much nucleotide variations were observed in cox1 gene sequences. The results of the present study showed a high infection rate among goats and sheep in southeastern Iran. A better understanding of the disease could be achieved when the parasite species, their molecular characterization and the extent of infection in the area are determined. It is fundamental to select a comprehensive control program in order to take proper preventive and therapeutic measures against the infection.

Prevalence and associated risk factors of Linguatula serrata infection in definitive and intermediate hosts in Iran and other countries: A systematic review

Linguatula serrata is known as a cosmopolitan zoonotic parasite whose adult form inhabits the upper respiratory system, nasal airways and frontal sinuses of dogs, foxes, cats and other carnivores, which are recognized as its final hosts. Its immature form resides in mesenteric lymph nodes, liver, lungs and spleen of herbivorous and other ruminants, which serve as its intermediate hosts. Both adult and nymphal stages of L. serrata can infect humans, which typically occurs via ingestion of eggs of infected dogs or consumption of raw or undercooked infected viscera of contaminated herbivores. The most common form of infection in human is nasopharyngeal linguatulosis, also known as Halzoun syndrome or Marrara syndrome. This paper presents a review of previous studies on L. serrata conducted in Iran from 1969 to 2018 and other countries. It was found that despite the fact that many studies have been conducted in Iran, the rate of infection with this parasite has not been studied in some areas of the country. In addition, the rate of infection with L. serrata increased with the age of ruminant animals and it was significantly higher in some areas. The prevalence of L. serrata nymphal infections in most areas was higher in goats in comparison to the other animals which can be an important risk factor for human infection. Although there was no significant difference in the rate of infection among male and female animals, the prevalence of L. serrata in male animals was typically lower than females. There was no significant difference in the seasonality of nymph infection.

Prevalence of Linguatula serrata nymphs in slaughtered sheep from Tehran province, Iran

Linguatulosis is a zoonotic disease caused by Linguatula serrata. Ruminants are the most important intermediate hosts of this parasite. This study was carried out to evaluate the prevalence rate of Linguatula serrata infection in slaughtered sheep in slaughterhouses of Tehran province, Iran. A total of 767 slaughtered sheep were selected in 2016 using systematic random sampling and their mesenteric lymph nodes were examined for Linguatula serrata nymph detection. Then, the infection rate and its intensity in different ages, sex and seasons were assessed. It was revealed that 66 sheep (8.6%) were infected with Linguatula serrata nymphs. Intensity of the infection was 4.88 nymphs. The highest rate of infection was observed in sheep aged over 19 months (P≤0.05). The highest infection rate and intensity of the infection were recorded in winter and summer, respectively (P≤0.05). Besides, intensity of the infection in females was significantly higher than that in males (P≤0.05). This study indicates the importance of Linguatula serrata infection in sheep in Tehran province, and the need to improve preventive measures for reducing the rate of infection and preventing transmission of the infection from sheep and other ruminant to other animals and humans in Iran.

Linguatula serrata (Porocephalida: Linguatulidae) Infection among Client-Owned Dogs in Jalingo, North Eastern Nigeria: Prevalence and Public Health Implications

Pentastomiasis is a parasitic zoonosis endemic to western and central Africa. This study was undertaken to determine the prevalence and public health implications of Linguatulosis in client-owned dogs in Jalingo, North Eastern Nigeria. Seven hundred and seventy seven (777) dogs brought for treatment at the hospital were subjected to buccal (sublingual) examination for pentastomiasis. Parameters such as age, sex, and breeds were determined. Also, the months of the year were taken into consideration. An overall prevalence of 37.45% was recorded. Of the 477 dogs examined in 2010, 184 were positive representing prevalence of 38.57% and in 2011 107 were positive representing prevalence of 35.67%. The infection was higher in the male than in the female which does not differ significantly (P > 0.05). There was no significant difference between sexes (P > 0.05). However, significant difference (P < 0.05) was observed between breeds and age of dogs examined. Season did not have much influence on the prevalence of Linguatulosis. The high prevalence of Linguatulosis in dogs and other animals found in this study highlights the need of improving preventative measures to reduce the rate of infection, which may pose a hazard to human health.

Prevalence of Linguatula serrata nymphs in slaughtered sheeps in Isfahan province, southwest of Iran

Linguatula serrata, well known as tongue worm; is an aberrant cosmopolitan parasite, which inhabits the carnivorous mammals (especially Canidae) respiratory system. The discharged eggs infect many plant feeder animals including human that produces visceral and nasopharyngeal linguatulosis which is known as Marrara syndrome in man. In current study, the prevalence rate of infection with L. serrata nymphs in mesenteric and mediastinal lymph nodes (MLNs) of slaughtered sheeps was investigated in Esfahan Province, Iran. The MLNs of 506 slaughtered sheeps, including 236 females and 270 males, were examined for L. serrata nymphs by cutting the MLNs longitudinally and then microscopic studies for L. serrata nymphs. Sheeps were categorized into four age groups, including <1 year, 1-2 years, 2-3 years and >3 years. Results showed that 11.66 % of examined sheeps were infected with L. serrata. Age had significant effect on the prevalence rate of this parasite in sheeps (infection in sheeps with >3 years old was more than other groups significantly) and sex had no significant effect on the prevalence rate of this parasite in sheeps. Infection rate in winter was significantly lower than infection rate in spring; but there were no significant differences between the other seasons. As high prevalence rate of infection in sheeps, suggesting possibly similar high rate of infection in other animals and man in the investigated area, which this emphasizes undertaking strict control measures to reduce risk of zoonotic outbreaks. This study was demonstrated infection rate of L. serrata in sheeps in central parts of Iran.

The prevalence of Linguatula serrata nymphs in mesenteric and mediastinal lymph nodes in one-humped camels (Camelus dromedarius) slaughtered in Rafsanjan slaughterhouse, Iran

Linguatula serrata is a well-known zoonotic parasite belonging to the order of Pentastomida which infects both human and animals. Human can be infected by both the nymph stage, causing a disease condition called nasopharyngeal linguatulosis or halzoun syndrome and the egg, a condition called visceral linguatulosis. The aim of this study was to evaluate the prevalence of nymphal stages of L. serrata in mesenteric and mediastinal lymph nodes of one-humped camels slaughtered in Rafsanjan slaughterhouse, Kerman province, south-eastern Iran. For this purpose, mesenteric and mediastinal lymph nodes of 132 one-humped camels of different sex and age groups in different seasons were examined. Overall, 27 one-humped camels (20.5 %) were infected by L. serrata nymphs. The infection rate increased with age (P < 0.05). No significant difference by sex groups or seasons was observed (P > 0.05). The high prevalence of infection in one-humped camels is of major concern to public health, owing to the zoonotic nature of the parasite and the potential risk of infection to humans and other animals.

Serine protease activities in Leishmania (Leishmania) chagasi promastigotes

The present work reports the isolation, biochemical characterization, and subcellular location of serine proteases from aqueous, detergent soluble, and culture supernatant of Leishmania chagasi promastigote extracts, respectively, LCSII, LCSI, and LCSIII. The active enzyme molecular masses of LCSII were about 105, 66, and 60 kDa; of LCSI, 60 and 58 kDa; and of LCSIII, approximately 76 and 68 kDa. Optimal pH for the enzymes was 7.0 for LCSI and LCSIII and 8.5 for LCSII, and the optimal temperature for all enzymes was 37°C, using α-N-ρ-tosyl-L: -arginine methyl ester as substrate. Assay of thermal stability indicated that LCSIII is the more stable enzyme. Hemoglobin, bovine serum albumin, and ovalbumin were hydrolyzed by LCSII and LCSI but not by LCSIII. Inhibition studies suggested that enzymes belong to the serine protease class modulated by divalent cations. Rabbit antiserum against 56-kDa serine protease of Leishmania amazonensis identified proteins in all extracts of L. chagasi. Furthermore, immunocytochemistry demonstrated that serine proteases are located in flagellar pocket region and cytoplasmic vesicles of L. chagasi promastigotes. These findings indicate that L. chagasi serine proteases differ from L. amazonensis proteases and all known flagellate proteases, but display some similarities with serine proteases from other Leishmania species, suggesting a conservation of this enzymatic activity in the genus.

Preliminary molecular characterization of the human pathogen Angiostrongylus cantonensis

Background

Human angiostrongyliasis is an emerging food-borne public health problem, with the number of cases increasing worldwide, especially in mainland China. Angiostrongylus cantonensis is the causative agent of this severe disease. However, little is known about the genetics and basic biology of A. cantonensis.

Results

A cDNA library of A. cantonensis fourth-stage larvae was constructed, and ~1,200 clones were sequenced. Bioinformatic analyses revealed 378 cDNA clusters, 54.2% of which matched known genes at a cutoff expectation value of 10^-20. Of these 378 unique cDNAs, 168 contained open reading frames encoding proteins containing an average of 238 amino acids. Characterization of the functions of these encoded proteins by Gene Ontology analysis showed enrichment in proteins with binding and catalytic activity. The observed pattern of enzymes involved in protein metabolism, lipid metabolism and glycolysis may reflect the central nervous system habitat of this pathogen. Four proteins were tested for their immunogenicity using enzyme-linked immunosorbent assays and histopathological examinations. The specificity of each of the four proteins was superior to that of crude somatic and excretory/secretory antigens of larvae, although their sensitivity was relatively low. We further showed that mice immunized with recombinant cystatin, a product of one of the four cDNA candidate genes, were partially protected from A. cantonensis infection.

Conclusion

The data presented here substantially expand the available genetic information about the human pathogen A. cantonensis, and should be a significant resource for angiostrongyliasis researchers. As such, this work serves as a starting point for molecular approaches for diagnosing and controlling human angiostrongyliasis.

Characterization of endopeptidases from the midgut of Morimus funereus (Coleoptera: Cerambycidae) larvae

Application of specific chromogenic substrates, use of class-specific inhibitors, and zymogram analysis enabled us to identify several peptidase classes in extracts of the midgut of Morimus funereus larvae. Zymogram analysis with gelatin as a peptidase substrate and phenylmethylsulfonyl fluoride as an inhibitor showed that serine peptidases were the most abundant endopeptidases in the midgut of M. funereus larvae. By zymogram analysis with gelatin as a peptidase substrate and 1,10-phenanthroline as an inhibitor, metallopeptidases were also detected. Analyses of serine peptidases with specific chromogenic substrates revealed dominance of elastase-like peptidases in extracts of the midgut of M. funereus larvae, with less pronounced chymotrypsin- and trypsin-like activities.