Use of ovotransferrin as an antimicrobial in turkeys naturally infected with Chlamydia psittaci, avian metapneumovirus and Ornithobacterium rhinotracheale

Ovotransferrin, an alternative and potential protein for diverse food and nutritional applications

Ovotransferrin(OVT)is a protein found in many types of egg white and has a wide range of functional properties. It has 50% homology with human/bovine lactoferrin, and is expected to be one of the most important alternative proteins for use in food and nutritional applications. This paper mainly reviews the structural characteristics and chemical properties of OVT, as well as its extraction and purification methods. It also systematically describes the various biological activities of OVT and its applications in food and medical industries. The challenges and limitations in the research of OVT were suggested. This review recommends some possible methods such as nanoparticle carriers and microencapsulation to improve the bioavailability and stability of OVT. In addition, this review highlights several strategies to overcome the limitations of OVT in terms of preparation and purification. This review systematically summarizes the recent advances in OVT and will provide guidance for the its development for food and nutritional applications.

Alternative strategies for Chlamydia treatment: Promising non-antibiotic approaches

Chlamydia is an obligate intracellular bacterium where most species are pathogenic and infectious, causing various infectious diseases and complications in humans and animals. Antibiotics are often recommended for the clinical treatment of chlamydial infections. However, extensive research has shown that antibiotics may not be sufficient to eliminate or inhibit infection entirely and have some potential risks, including antibiotic resistance. The impact of chlamydial infection and antibiotic misuse should not be underestimated in public health. This study explores the possibility of new therapeutic techniques, including a review of recent studies on preventing and suppressing chlamydial infection by non-antibiotic compounds.

A comprehensive review on avian chlamydiosis: a neglected zoonotic disease

Avian chlamydiosis is one of the important neglected diseases with critical zoonotic potential. Chlamydia psittaci, the causative agent, affects most categories of birds, livestock, companion animals, and humans. It has many obscured characters and epidemiological dimensions, which makes it unique among other bacterial agents. Recent reports on transmission from equine to humans alarmed the public health authorities, and it necessitates the importance of routine screening of this infectious disease. High prevalence of spill-over infection in equines was associated with reproductive losses. Newer avian chlamydial species are being reported in the recent years. It is a potential biological warfare agent and the disease is an occupational hazard mainly to custom officers handling exotic birds. Prevalence of the disease in wild birds, pet birds, and poultry causes economic losses to the poultry industry and the pet bird trade. Interestingly, there are speculations on the ‘legal’ and ‘illegal’ bird trade that may be the global source of some of the most virulent strains of this pathogen. The mortality rate generally ranges from 5 to 40% in untreated cases, but it can sometimes be higher in co-infection. The intracellular lifestyle of this pathogen makes the diagnosis more complicated and there is also lack of accurate diagnostics. Resistance to antibiotics is reported only in some pathogens of the Chlamydiaceae family, but routine screening may assess the actual situation in all pathogens. Due to the diverse nature of the pathogen, the organism necessitates the One Health partnerships to have complete understanding. The present review focuses on the zoonotic aspects of avian chlamydiosis with its new insights into the pathogenesis, transmission, treatment, prevention, and control strategies. The review also briefs on the basic understandings and complex epidemiology of avian chlamydiosis, highlighting the need for research on emerging one health perspectives.

Transferrins Reduce Replication of Chlamydia suis in McCoy Cells

Chlamydia suis (C. suis) resides in the intestines of pigs and tetracycline-resistant strains are emerging worldwide. Intestinal infections are often subclinical. However, the gut is regarded as a C. suis reservoir and clinical infections have been associated with enteritis, conjunctivitis, pneumonia and reproductive failure. C. suis was found in boar semen and venereal transmission occurred. We studied the anti-Chlamydia suis activity of ovotransferrin (ovoTF) and bovine lactoferrin (bLF). Pre-incubation of C. suis with bLF or ovoTF had no significant effect on overall chlamydia replication (mean fluorescence area) in McCoy cells. The addition of ovoTF to the culture medium had no effect on bacterial replication, but the addition of 0.5 or 5 mg/mL of bLF significantly reduced the inclusion size by 17% and 15% respectively. Egg components are used for cryopreservation of boar semen. When inoculating an ovoTF-containing and Chlamydia suis-spiked semen sample in McCoy cells, a significant reduction in inclusion number (by 7%) and overall replication (by 11%) was observed. Thus, we showed that transferrins possess anti-chlamydial activity. Moreover, ovoTF addition to semen extenders might reduce C. suis venereal transmission. Further research is needed to unravel the mechanisms behind the observations and to enhance the effect of transferrins on C. suis.

Functional properties of ovotransferrin from chicken egg white and its derived peptides: a review

With emerging trends in the food and pharmaceutical industries, potential applications of egg-derived bioactive compounds were recognized. Ovotransferrin is a major egg white functional protein responsible for multiple bioactivities. The objectives of this review are to provide scientific evidence of the functional properties of chicken ovotransferrin and its derived peptides and to identify future research approaches and applications. Various easy, economical, and non-toxic methods have been reported to produce ovotransferrin with high yield and purity, and chemical and enzymatic approaches have been employed to release bioactive peptides. The native ovotransferrin is known to have antimicrobial, antioxidant, anticancer, and immunomodulatory activities. The peptides produced from ovotransferrin also are reported to have antioxidant, antimicrobial, antihypertensive, and anticancer properties. However, little or no application of these compounds in the food and pharmaceutical areas is available yet. Therefore, the practical application of OTF in nutraceutical and pharmaceutical areas are among the emerging areas of research.

Porcine and Bovine Forms of Lactoferrin Inhibit Growth of Porcine Enterotoxigenic Escherichia coli and Degrade Its Virulence Factors

Postweaning diarrhea (PWD) is an economically important, multifactorial disease affecting pigs within the first 2 weeks after weaning. The most common agent associated with PWD is enterotoxigenic Escherichia coli (ETEC). Currently, antibiotics are used to control PWD, and this has most likely contributed to an increased prevalence of antibiotic-resistant strains. This puts pressure on veterinarians and farmers to decrease or even abandon the use of antibiotics, but these measures need to be supported by alternative strategies for controlling these infections. Naturally derived molecules, such as lactoferrin, could be potential candidates due to their antibacterial or immune-modulating activities. Here, we analyzed the ability of bovine lactoferrin (bLF), porcine lactoferrin (pLF), and ovotransferrin (ovoTF) to inhibit ETEC growth, degrade ETEC virulence factors, and inhibit adherence of these pathogens to porcine intestinal epithelial cells. Our results revealed that bLF and pLF, but not ovoTF, inhibit the growth of ETEC. Furthermore, bLF and pLF can degrade several virulence factors produced by ETEC strains, more specifically F4 fimbriae, F18 fimbriae, and flagellin. On the other hand, ovoTF degrades F18 fimbriae and flagellin but not F4 fimbriae. An in vitro adhesion assay showed that bLF, ovoTF, and pLF can decrease the number of bacteria adherent to epithelial cells. Our findings demonstrate that lactoferrin can directly affect porcine ETEC strains, which could allow lactoferrin to serve as an alternative to antimicrobials for the prevention of ETEC infections in piglets.IMPORTANCE Currently, postweaning F4⁺ and F18⁺ Escherichia coli infections in piglets are controlled by the use of antibiotics and zinc oxide, but the use of these antimicrobial agents most likely contributes to an increase in antibiotic resistance. Our work demonstrates that bovine and porcine lactoferrin can inhibit the growth of porcine enterotoxigenic E. coli strains. In addition, we also show that lactoferrin can reduce the adherence of these strains to small intestinal epithelial cells, even at a concentration that does not inhibit bacterial growth. This research could allow us to develop lactoferrin as an alternative strategy to prevent enterotoxigenic E. coli (ETEC) infections in piglets.

Overexpressing ovotransferrin and avian β-defensin-3 improves antimicrobial capacity of chickens and poultry products

Zoonotic and foodborne diseases pose a significant burden, decreasing both human and animal health. Modifying chickens to overexpress antimicrobials has the potential to decrease bacterial growth on poultry products and boost chicken innate immunity. Chickens overexpressing either ovotransferrin or avian β-defensin-3 (AvβD3) were generated using Tol-2 transposons. Transgene expression at the RNA and protein level was seen in egg white, breast muscle, and serum. There were significant differences in the immune cell populations in the blood, bursa, and spleen associated with transgene expression including an increased proportion of CD8+ cells in the blood of ovotransferrin and AvβD3 transgenic birds. Expression of the antimicrobials inhibited the in vitro growth of human and chicken bacterial pathogens and spoilage bacteria. For example, transgene expression significantly reduced growth of aerobic and coliform bacteria in breast muscle and decreased the growth of Salmonella enterica in egg white. Overall these results indicate that overexpression of antimicrobials in the chicken can impact the immune system and increase the antimicrobial capacity of poultry products.

Co-infection of Chlamydia psittaci with H9N2, ORT and Aspergillus fumigatus contributes to severe pneumonia and high mortality in SPF chickens

Since 2007, most areas of China have seen outbreaks of poultry airsacculitis, which causes hugely economic losses to the poultry industry. However, there are no effective measures to combat the problem. In this study, 105 rations were collected to isolate Aspergillus spp. from the diseased farms. In subsequent experiments, SPF chickens were inoculated with Ornithobacterium rhinotracheale (ORT), Chlamydia psittaci (C. psittaci) and Aspergillus fumigatus (A. fumigatus), and mortality rate, body weight gain and lesion score were evaluated. Of these ration samples, 63 (60.0%) were A. fumigates, 21 (20.0%) were Aspergillus niger (A. niger) and 11 (10.5%) were Aspergillus candidus (A. candidus). Furthermore, SPF birds infected with C. psittaci, ORT, H9N2 virus and A. fumigatus conidia exhibited a mortality rate of 40%, while simultaneous co-infection with C. psittaci, ORT and A. fumigatus resulted in a mortality rate of 20%. The avian airsacculitis was manifested in the C. psittaci + ORT/A. fumigatus, C. psittaci + H9N2 + ORT/A. fumigatus and C. psittaci + H9N2/A. fumigatus groups while others had transient respiratory diseases without mortality. Our survey indicates that feed-borne A. fumigatus is prevalent in poultry rations. The combination of C. psittaci, ORT, H9N2 and A. fumigatus conidia contributes to the replication of avian airsacculitis by aggravating the severe damage to the air sacs and lungs of chickens.

Natural Products for the Treatment of Chlamydiaceae Infections

Due to the global prevalence of Chlamydiae, exploring studies of diverse antichlamydial compounds is important in the development of effective treatment strategies and global infectious disease management. Chlamydiaceae is the most widely known bacterial family of the Chlamydiae order. Among the species in the family Chlamydiaceae, Chlamydia trachomatis and Chlamydia pneumoniae cause common human diseases, while Chlamydia abortus, Chlamydia psittaci, and Chlamydia suis represent zoonotic threats or are endemic in human food sources. Although chlamydial infections are currently manageable in human populations, chlamydial infections in livestock are endemic and there is significant difficulty achieving effective treatment. To combat the spread of Chlamydiaceae in humans and other hosts, improved methods for treatment and prevention of infection are needed. There exist various studies exploring the potential of natural products for developing new antichlamydial treatment modalities. Polyphenolic compounds can inhibit chlamydial growth by membrane disruption, reestablishment of host cell apoptosis, or improving host immune system detection. Fatty acids, monoglycerides, and lipids can disrupt the cell membranes of infective chlamydial elementary bodies (EBs). Peptides can disrupt the cell membranes of chlamydial EBs, and transferrins can inhibit chlamydial EBs from attachment to and permeation through the membranes of host cells. Cellular metabolites and probiotic bacteria can inhibit chlamydial infection by modulating host immune responses and directly inhibiting chlamydial growth. Finally, early stage clinical trials indicate that polyherbal formulations can be effective in treating chlamydial infections. Herein, we review an important body of literature in the field of antichlamydial research.

Emergencies and Critical Care of Commonly Kept Fowl

Fowl are birds belonging to one of the 2 biological orders, the game fowl or land fowl (Galliformes) and the waterfowl (Anseriformes). Studies of anatomic and molecular similarities suggest these two groups are close evolutionary relatives. Multiple fowl species have a long history of domestication. Fowl are considered food-producing animals in most countries and clinicians should follow legislation regarding reportable diseases and antibiotic use, even if they are pets. This article reviews aspects of emergency care for most commonly kept fowl, including triage, patient assessment, diagnostic procedures, supportive care, short-term hospitalization, and common emergency presentations.

Longitudinal monitoring for respiratory pathogens in broiler chickens reveals co-infection of Chlamydia psittaci and Ornithobacterium rhinotracheale

Chlamydia psittaci is prevalent in broiler chicken production. However, the role of C. psittaci in the respiratory disease complex needs to be clarified. Our aim was to identify the time point when a C. psittaci infection appeared on a broiler farm and to examine the presence of other respiratory pathogens at that time. We focused on the 'major' respiratory pathogens occurring in Belgian broilers, namely infectious bronchitis virus (IBV), avian metapneumovirus (aMPV), Ornithobacterium rhinotracheale, Mycoplasma gallisepticum and Mycoplasma synoviae, and examined their co-occurrence with C. psittaci on three commercial broiler farms. For all farms, 1-day-old broilers showed high maternal antibody titres against C. psittaci in the presence of viable C. psittaci. Maternal antibodies seemed to protect against respiratory signs. Maternal antibodies declined and clinical outbreaks could be identified serologically even before maternal antibodies completely disappeared. Mixed infections with genotypes B/C and B/C/D were observed. Broilers with C. psittaci antibody increases showed conjunctivitis, signs of upper respiratory disease and dyspnoea. C. psittaci always preceded an O. rhinotracheale infection. Infections with aMPV, IBV or Mycoplasma spp. were not observed. Evidence was provided that C. psittaci could occur at an early age in broilers without a predisposing respiratory infection. Both C. psittaci and O. rhinotracheale should be considered when developing prevention strategies for respiratory disease in broilers.

Chlamydial biology and its associated virulence blockers

Chlamydiales are obligate intracellular parasites of eukaryotic cells. They can be distinguished from other Gram-negative bacteria through their characteristic developmental cycle, in addition to special biochemical and physical adaptations to subvert the eukaryotic host cell. The host spectrum includes humans and other mammals, fish, birds, reptiles, insects and even amoeba, causing a plethora of diseases. The first part of this review focuses on the specific chlamydial infection biology and metabolism. As resistance to classical antibiotics is emerging among Chlamydiae as well, the second part elaborates on specific compounds and tools to block chlamydial virulence traits, such as adhesion and internalization, Type III secretion and modulation of gene expression.