eChapters

Introduction

Parvoviruses are nonenveloped, single-stranded DNA viruses belonging to the genus Protoparvovirus, member of the Parvoviridae family, that has been included within the species Carnivore protoparvovirus 1, together with Feline panleukopenia virus (FPV), Mink enteritis virus (MEV) and Raccoon parvovirus (RPV), according to the International Committee on Taxonomy of Viruses (Tijssenet al 2011). Two distinct parvoviruses are known to infect dogs—the pathogenic CPV 2 and CPV-1 or the minute virus of canine (MVC). CPV-2, the causative agent of acute hemorrhagic enteritis and myocarditis in dogs, is one of the most important pathogenic viruses with high morbidity (100%) and frequent mortality up to 10% in adult dogs and 91% in pups. CPV-2 is the etiologic agent of a contagious disease, mainly characterized by clinical gastroenteritis signs in younger dogs. This virus that causes the disease “parvo”, first emerged among dogs in Europe around 1976. By 1978 the virus had spread unchecked, causing a worldwide epidemic of myocarditis and inflammation in the intestines (gastroenteritis) and could infect domestic dogs, spreading in the global dog population within 2 years. This original type, was rapidly replaced by two antigenic variants, types 2a and 2b (Parrish et al 1985, 1991), and in 2000 a third type CPV-2c was detected (Buonavogliaet al 2001). Canine parvovirus (CPV) is responsible for acute gastroenteritis in pups, with a high rate of mortality (Carmichael and Binn, 1981). We now know the virus is not limited to dogs, but is capable of causing infections in wild canines such as coyotes and wolves, and other wild animals, including foxes, raccoons and skunks. Since its emergence in 1978, it was and remains a common and important cause of morbidity and mortality in young dogs.

Introduction

The preservation of animal specimens for museums is a critical practice in natural history, enabling education, research, and conservation awareness. Traditionally, specimens are often sourced from zoological facilities or specific conservation programs. However, the innovative use of fallen animals—animals that have died of natural causes or accidents—presents a sustainable and ethical method of specimen preparation. India has large livestock population. As per 20th livestock census in the country, livestock sector of India comprised of 303 million bovines (Cattle, Buffalo, Mithun and Yak), 74.26 million sheep, 148.88 million goats, 9.06 million pigs and about 851.81 million poultry. Each year large number of livestock is lost due to natural disaster such as flood, cyclones, draughts avalanches, landslides, snowstorm and forest fire. Approximately 55% of its buffalo, 38% of its cattle, 41% of its goats and 47% of its pigs are vulnerable to floods which regularly destroy farmlands. On the other hand, 44% of country’s livestock are affected by draught. Cyclones also causes huge loss to the livestock as well as to the wildlife. According to Down to Earth magazine and Centre for Science and Environment approximately 92519 livestock were killed in India in 2023 due to extreme weather including cyclones.

Introduction

“Invest in Women: Accelerate Progress” -the theme of the International Women’s Day 2024 celebrated by the United Nations and multiple organizations across the world highlighted the need of review of different works and efforts in bringing gender equality in various development departmentsincluding agriculture and allied sectors. This reflects the importance being given to the efforts towards gender equality at the highest level.

Agrifood systems are a major employer of women globally and constitute a more important source of livelihood for women than for men in many countries. Empowering women and closing gender gaps in agrifood systems thus, enhances the well-being of women and their households, reducing hunger, boosting incomes and strengthening resilience.Increasing women’s empowerment is essential for women’s well-being and has a positive impact on agricultural production, food security, diets and child nutrition. Also,the gender-transformative approaches to change restrictive social norms are cost effective and have high returns, but morework is needed on developing pathways to implement gender-transformative approaches.

Introduction

Emerging and reemerging infectiousdiseases are defined as the diseases of which the incidence has shown an increasing trend in the recent past or threatening to increase in the near future. Emerging infectious disease (EID) are caused by apathogen previously unknown to cause disease orre-emerging pathogens, which have previously causeddisease but now reveal increased infectivity orextended transmission ranges that improve their ability to cause disease in human populations. Today, whole world is facing a concerning rise in emerging infectious diseases and the majority of EID have been observed in the past decades.Multiple recent EID outbreaks e.g. the 2003 SARS and the 2012 MERS outbreaks, the 2009 swine flu pandemic,the 2013–2016 Ebolavirus epidemic, the 2014chikungunya outbreak in the Western Hemisphere,the 2015 Zika and the 2019 SARS Cov 2 virus epidemic have exhibited significantmorbidity and mortality and large geographicranges. These outbreakshave indicated the potential for evenmore severe outcomes in future outbreaks. Severaladditional pathogens are also considered capable ofproducing EID outbreaks, these include Escherichia coliO157:H7, hantavirus, dengue virus and West Nilevirus, while malaria, tuberculosis (TB), cholera, andinfluenza are often considered reemerging diseases with the potential for new outbreaks.Many newly emerging diseases in humans are actually long-standing zoonosesof animal host species that appeared inhuman populations following a climatic or environmental change. The complex interplay between climate change, ecosystems, and human activities have created conditions that favour the emergence and spread of infectious diseases posing significant challenges to public health. Although, improved sanitation, increased access to health care, and advances in preventive and clinical medicine have reduced the mortality and morbidity rates of several infectious diseases.

Introduction

The gut microbiota is the complex and dynamic community of microorganisms that includes various bacteria, fungi and other microorganisms, proliferate and lead a symbiotic/mutual relationship with the host system. These microorganisms protect the host against pathogens by unique mechanisms, helps to maintain shape and strengthen the intestinal epithelium and boost immune response. Diverse bacterial metabolites can immigrate the host bloodstream and other parts of the body via various channels in humans and animals, such as gut-microbiota-brain, gut microbiota-skin, gut-vagina, gut liver, gut-bones etc. However, many aspects of modern lifestyle would alter the gut microbiota and lead to numerous diseases including inflammatory bowel disease, diabetes mellitus, obesity, and metabolic syndrome. Probiotics and other beneficial microbes exert many beneficial effects on their hosts by modulating the gut microbiota. While the term probiotic is reserved only for well-characterised strains with clinically proven health benefits, other beneficial microorganisms include, organisms responsible for the fermentation of foods viz. yogurt, kefir, kombucha, kimchi and many others that have been shown to have distinct health benefits. Interestingly, major group of these beneficial organisms belong to lactic acid bacteria.

Introduction

Lactic acid bacteria (LAB) are characterized as Gram-positive cocci or rods, non-aerobic but aerotolerant, able to ferment carbohydrates for production of energy and lactic acid. Lactic acid bacteria includes different major genera: Lactococcus, Enterococcus, Lactosphaera, euconostoc, Melissococcus, Oenococcus, Pediococcus, Streptococcus, Tetragenococcus, Vagococcus and Weissella. Other genera are Aerococcus, Microbacterium, Propionibacterium and Bifidobacterium. Through carbohydrate fermentation along with lactic acid, various organic acids are produced due to which there is a fall in pH level and creates unfavorable environment or inhibits growth of some undesired microorganisms. The low pH makes organic acids lipo -soluble, allowing them to invade into cytoplasm of pathogens by rupturing cell membrane. LAB are generally regarded as safe (GRAS), and have a significant role in the preservation of foods and fermented products. Under controlled conditions they can be used as natural competitive microbiota or as specific starter cultures. Antagonistic substance like bacteriocins are produced from lactic acid bacteria that inhibits the activity and growth of other bacteria and these bacteriocins are active against various pathogens in minimum concentration. These are antimicrobial peptides modified by post -translational mechanisms and exported to the extracellular medium. Till date about 239 bacteriocin producing LAB genome and 789 putative bacteriocin producing genes cluster are stored in the public databases. Many gram positive and gram negative bacteria in the environment produce bacteriocins.

Introduction

Let food be thy medicine and medicine be thy food- the age-old quote by Hippocrates, is certainly the tenet of today. Microbial cultures have been used for millenniums in food and alcoholic fermentations and in the past century have undergone scientific scrutiny for their ability to prevent and cure a variety of diseases. Later it became popular in improving human and farm animal nutritive values and recently in aquaculture also. The growing interest in the understanding the role of food in human health has moved from its primary role as a source of energy to the subtle action of biologically active food components on human health. Henceforth functional foods or nutraceuticals are of great demand in present time. The growing scientific evidence suggests that the food supplements containing beneficial bacteria can provide an array of benefits to the host. Now a day’s probiotic fermented foods are in great demand due to the awareness of beneficial aspects of probiotics among people. Several industries focused on the improvement of conventional fermented foods scientifically in order to fetch good market for their products. Particularly, animal feed companies and researchers have been looking for alternative products and strategies that can help to maintain animal gut health in order to prevent or reduce the prevalence of pathogens in the food chain. After understanding the mechanism and beneficial aspects of probiotics in detail at molecular level in earlier chapters, now it is relevant to discuss the applied part of probiotics. In this chapter, commercial importance of probiotics and probiotics derived products at industrial level are emphasized.

Diversity of gut microbial community

The human microbiota (the collection of microbes that live on and inside us) consists of about 100 trillion microbial cells that outnumber our ‘‘human’’ cells 10 to 1, and that provide a wide range of metabolic functions that we lack. It has been estimated that they encode 100-fold more unique genes than our own genome. Furthermore, the gut microbes contribute to energy harvest from food, and changes of gut microbiome may be associated with bowel diseases or obesity. To understand and exploit the impact of the gut microbes on human health and well-being it is necessary to decipher the content, diversity and functioning of the microbial gut community. If we consider ourselves as superior organisms encompassing these microbial symbionts, by far the majority of genes in the system are microbial. In this sense, completing the human genome also requires the characterization of the microbiome (the collection of genes in the microbiota).

Methods of counting viable and non-viable bacteria in gut

Before the advent of genome sequencing and genome-wide analysis method, our knowledge of molecular characteristics of diverse gut microbial population was extremely limited. To obtain an estimate of cultivability, microbial ecologists generally compare microscopic counts with total viable counts. The total viable count made on a nonselective agar based medium estimates the number of colony forming units (cfu) per gram of sample. The finding that total viable counts are typically lower than total microscopic counts was thought to be due to the number of dead cells. Indeed, dead bacteria in feces may constitute up to one third of the total bacterial community. However, recent nucleic acid based studies indicated that a majority of bacteria in a variety of ecosystems are different from those described in culture.

Introduction

It became clear from the discussions of previous chapters that probiotics perform metabolic functions such as fermenting indigestible dietary residues and endogenous mucus, production of vitamins, and absorption of minerals. They also play key role in intestinal epithelial cell proliferation and differentiation, and the homeostasis of the immune system. Further, probiotics are also known to involve in modifying gut pH, antagonizing pathogens through the production of antimicrobial compounds, competing with pathogens for recept or sites as well as for available nutrients and growth factors, stimulating immunomodulatory cells of the host, and produce a wide range of enzymes such as lactase, amylase, lipase, protease, phytase and so on. The molecular mechanisms of probiotics are largely unknown and opens avenue for research in probiotics. Moreover, current research in probiotics and health consciousness in the public lead to an increased interest towards probiotics from the public, researchers, governmental organizations (such as the WHO/FAO) and medicine and food companies. In this chapter, application of probiotics in treating various diseases and disorders are discussed.

Introduction

Cell surface components such as adhesins, polysaccharides, and proteins play major roles in the adherence of probiotic bacteria to the intestinal epithelium, interactions that might lead to pathogen exclusion and immunomodulation of host cells. Probiotic bacteria have the ability to produce exocellular polymers called Exopolysachcharides (EPSs). These exocellular polymers present in the surface of many lactic acid bacteria, including Lactobacilli.The adhesive properties of lactobacilli are directly linked to their surface properties which are influenced by the structure and composition of their cell wall. The cell envelope of lactobacilli, bacteria, is composed of the bilipidic plasma membrane with embedded proteins encompassed by the cell wall. The bacterial cell wall consists of a thick multilayered sacculus made of peptidoglycan (PG) with teichoic acids (wall teichoic acids (WTA) and/or lipoteichoic acids (LTA)), exopolysaccharides (EPS), proteinaceous filaments called pili, and proteins that are anchored to the cell wall through different mechanisms (Figure 1).

Some species of lactobacilli possess an additional paracrystalline layer of proteins surrounding the PG layer, referred to as the S layer. These macromolecules together may play crucial roles in determining species and strain-specific characteristics of lactobacilli by influencing host-microbe interactions and microbial adaptations to the changing host environment. Several studies implicate that cell surface components, either individually or collectively, involve in host-microbe interactions. Lactobacilli beneficially affect the host in many ways by producing abundant variety of EPSs through the activity of extracellular glycosyl transferases. Approximately 30 species of lactobacilli are described as EPS producers. Among them, the best known are L. casei, L. acidophilus, L.brevis, L. curvatus, L. delbrueckii bulgaricus, L. helveticus, L. rhamnosus, L. plantarum, L. johnsonii, etc.

Introduction

Preceding chapters discuss the essentials of probiotics, their role in maintaining gut health in combination with prebiotics and significance of systematic classification of probiotic isolates. Further, to draw an idea how probiotics function in the gut, it is essential to know the interaction of probiotics with other microorganisms in the gastrointestinal milieu - the site of their probiotic action. Knowledge in the ecology of probiotic microorganisms in host environment such as gut gives an ideal picture of their functioning manner and the factors (both host and microbial) responsible for it.

Study of microbial ecology in the gastrointestinal tract is very difficult since gut harbors highly diversified microflora that varies not only at species level but also at individual level. The diversity of gut microflora in two healthy individuals of same species may exhibit variations in their composition and it may be influenced by geodemographic factors also. In this regard, the present chapter deals with the study of ecology of Lactobacillus- most commonly used probiotic bacteria in the gastrointestinal tract which in turn helps in framing selection criteria for screening of potential probiotics.

Recent studies on interaction between human and gut microflora discussed that co-evolution between microorganisms and their host have contributed for the development of a very complex microbial diversity in the gut. Highly diversified microflora in the human gut is a consequence of natural selection at two levels, top-down and bottom-up selection pressure. Hierarchy theory expounds that higher levels compel lower levels for possible organizational solutions i. e. organisms at the higher levels govern the structure or population dynamics of an ecosystem while on contrary lower levels control the structure of ecology when bottom-up level is the selection pressure. In case of interaction between human and gut microflora, being host human is at higher level in the hierarchy for selection and as mentioned above, top down selection pressure is driven by higher levels; host selects the beneficial microorganisms for functional redundancy leading to the development of a microbial community with divergent microbial divisions. Chances for lateral gene transfer also thought to influence the selection process and there by structure of the microbial community. On the other hand, competition among the members of host selected microbiota exert bottom up selection pressure resulting in the development of highly specialized genomes with functionally prominent set of genes. Natural selection at host level obviously favors functionally constant microbial communities which benefits the host with functional redundancy encoded in their genomes. Mean while bottom-up cell-level selection pressure aspire to favor niche specialization to avoid competition between the members of microbial community. In order to be a part of specialized niche, to become more potent microorganisms adapt a particular set of abiotic and biotic factors within the habitat by acquiring new sets of genes essential for their survival and thus escape the competition from decrepit microbial species.

Introduction

From earlier chapters, it is evident that Lactobacilli and Bifidobacteria are the two important genera that have potent applications in food microbiology and human nutrition due to their role in food and feed production, preservation and also due to probiotic potentialities. Most of the bacterial species are still unknown indicating that the identification and classification of bacteria is a hard task since the beginning of microbiology and consequently our knowledge about bacterial ecology is very low. Mean while the expectations about novel bacterial products are high. Therefore, bacterial identification has become a growing field of interest in microbiology. Since, Lactobacilli and Bifidobacteria genera include a large number of species and strains exhibiting important properties in an applied context, chiefly in the area of probiotics as food and therapeutics, an updated list of species belonging to these two genera, their phylogenetic relationships and other relevant taxonomic information are of great significance. The classification and identification of a probiotic isolate at strain level point out its typical habitat and origin. Moreover, the species, or genus name, may also indicates the strain’s safety and technical applicability for its use in probiotic products. Taxonomy helps to place a newly identified organism in a relevant group and enables the scientific communication. Further it facilitates the construction of databases that can be used for rapid identification of organisms at laboratory level easily. Thus, taxonomy of Lactobacilli and Bifidobacteria helps to study these organisms scientifically and allows characterizing and arranging them in an orderly manner which promote the scientific community to explore the benefits from those organisms for the betterment of mankind.

Introduction

Probiotics, prebiotics and synbiotics are interrelated terms. Probiotic is discussed in detail in previous chapter. In this chapter, prebiotics and its effect on gut along with probiotics are emphasized. Prebiotics can be defined as non digestible food ingredients that stimulate the growth and/or activity of bacteria in the digestive system in ways claimed to be beneficial to health. They were f irst identified and named by Marcel Roberfroid in 1995. He defined prebiotic as a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well-being and health. Further, FAO defined prebiotic as “a non-viable food component that confers a health benefit on the host associated with modulation of the microbiota.”Whereas the term synbiotics refers to a product that contains both probiotics and prebiotics in the form of synergism. A synbiotic has been defined as “a mixture of prebiotics and probiotics that beneficially affect the host by improving the survival and implantation of live microbial dietary supplements in the gastrointestinal tract, by selectively stimulating the growth and activating the metabolism of one or a limited number of health promoting bacteria, and thus improving host welfare”. As described above, the combined use of prebiotics and probiotics is often described as synbiotic, but the United Nations Food & Agriculture Organization (FAO) recommends that the term “synbiotic” be used only if the net health benefit is synergistic.

The term probiotic means “for life” and it is currently used to refer bacteria that are associated with beneficial effects for humans and animals. The credit for first observation made on the positive role of some selected bacteria was attributed to Eli Metchnikoff, the Russian born Nobel Prize recipient, worked at the Pasteur Institute in the beginning of the last century. Metchnikoff suggested that - “the dependence of the intestinal microbes on the food makes it possible to adopt measures to modify the microflora in our bodies and to replace the harmful microbes by useful microbes”. Interim Henry Tissier, a French paediatrician, observed that children with diarrhea in their stools had a low number of bacteria which are characterized by a peculiar Y shaped morphology. On the contrary, these “bifid” bacteria were abundant in healthy children. Based on these observations, Tissier suggested that “bifid” bacteria could be administered to patients with diarrhoea to help restore a healthy gut microflora. These two scientists were the first to give scientific intimation for the use of probiotics when even the term probiotics was not coined. Later in 1965, the term probiotics is coined by Lilly and Stillwell to describe substances produced by one microorganism, that stimulate the growth of another. Subsequently, Parker defined probiotics as organisms and substances that contribute to intestinal balance. Further, Fuller (1989) improved the Parker’s definition of probiotics as “live microbial feed supplements which beneficially affect the host animal by improving its intestinal microbial balance”. Havenaar and Huis in’t Veld (1992) extended the probiotic definition with the description: “A viable mono or mixed culture of microorganisms which, applied to animal or man, beneficially affects the host by improving the properties of the indigenous microflora”. At the end of the millennium, Salminen and his coworkers (1999) proposed the following definition: “probiotics are microbial cell preparations or components of microbial cells that have a beneficial effect on the health & well- being of host”. Whereas FAO/WHO (2001) defined probiotics as “living bacteria that, when administered in adequate amounts, confer a health benefit on the host”. This definition for probiotics is widely accepted.

Introduction

Colorimetry is a scientific technique widely used across various fields to quantify the concentration of substances based on their color intensity. Colorimetry is a branch of analytical chemistry that focuses on measuring the absorbance or transmission of light by colored solutions. It utilizes the principles of optics and spectroscopy to determine the concentration of a substance in a solution based on its color intensity. This technique relies on the Beer-Lambert law, which states that the absorbance of light by a solution is directly proportional to its concentration and path length.

Principles of Colorimetry

The fundamental principle of colorimetry lies in the interaction of light with matter. When light passes through or is reflected off a substance, certain wavelengths are absorbed, while others are transmitted or reflected. The color we perceive is due to the wavelengths of light that are reflected back to our eyes. In colorimetry, a photometric measurement is made using a colorimeter or spectrophotometer, which quantifies the intensity of light absorbed or transmitted by a sample.

Introduction

Biochemistry is branch of life science which deals with the study of chemical reactions occurring in the living cells and organisms. The term biochemistry was first introduced by German chemist Carl Neuberg in 1903. Since biochemistry is associated with the biological reactions and energy changes associated with these reactions or transformations within the living cell, biochemistry may thus be treated as a discipline in which biological phenomenon are analysed in terms of chemistry. The branch of biochemistry for the same reason has been variously named as “Biological Chemistry” or “Chemical Biology”. Modern biochemistry has two branches descriptive and dynamic biochemistry. Descriptive biochemistry deals with qualitative and quantitative characterization of the various chemical components of cell and the dynamic biochemistry deals with the elucidation of the nature and the mechanism of reactions involving these chemical cell components.

Qualitative analysis of biological sample deals with the examination of the organic or inorganic cell associated components in order to determine its composition. It denotes the presence of various biomolecules, elements or groups of elements that are present in the sampling population. It is possible to determine whether a particular component is present or absent in a sample by performing a qualitative analysis of the sample. Qualitative analysis is the identification of elements, species and/or compounds present in a sample.

Introduction

Urinalysis, the examination of normal and abnormal components of urine, is one of the most important aspect of clinical pathology that aids in accurate and timely diagnosis in veterinary practice. Urine is considered as one of the most accessible bio-fluid that can be collected using non- invasive techniques in adequate quantities. It includes the evaluation of colour, odour, turbidity, volume, pH, specific gravity, protein and glucose content, ketone bodies, blood, erythrocytes, leukocytes, epithelial cells, casts, crystal, micro-organisms, etc. Urinalysis gives us valuable information regarding the several important attributes of renal function. For example, specific gravity of urine gives valuable insights over the potential of the Henle’s loop to dilute urine and the distal convoluted tubules to concentrate urine after ruling out the extra-renal factors affecting the urine specific gravity. It is highly useful to evaluate the different types of urogenital diseases and it also provides significant information regarding several systemic disorders. It is comparatively quicker to perform and is relatively a low-cost test that could be easily done in most clinical setups.

Introduction

Biological fluids refer to any liquid substances found within living organisms that play essential roles in physiological functions. These fluids can include blood, urine, cerebrospinal fluid, saliva, digestive juices, rumen fluid, peritoneal fluid, pleural fluid, pericardial fluid, synovial fluid, amniotic fluid, milk etc.

Collection of biological fluids refers to the process of gathering various types of bodily f luids from animals for scientific study or medical purposes. This collection often involves techniques like blood draws, urine collection, cerebrospinal fluid sampling, saliva collection, etc., depending on the specific fluid and the research or diagnostic needs. These f luids are valuable for understanding the health, metabolism, genetics, and other aspects of animal biology. Collecting and analyzing these biological fluids is crucial for understanding health and disease processes, diagnosing illnesses, monitoring treatment effectiveness, and advancing medical and scientific research.

Introduction

Immunology deals with the body defence system consisting of various cells and biomolecules that prevents entry of foreign infectious and toxic agents by different mechanisms. The mammalian immune system operates in two ways like innate or non specific immunity and adaptive or acquired or specific immunity. Innate part constitutes the physical (skin, hair, tears and mucous secretions) containing enzymes that prevents primarily entry of pathogen. It is the first line of defence action, very fast but not adequate. Adaptive form constitutes defensive cells and secreted immunoglobulins. It takes time to develop effectively, especially when the body sees the organism for the first time. Immunoglobulins (Ig) or antibodies are a group of proteins produced from B lymphocytes and plasma cells in response to the presence of any foreign substances. They are 5 basic types like M, A, G, E and D each with specific function. The system can produce antibody molecules, directed to about 1 million different kinds of antigens. All immunoglobulins have a similar basic structure.

Introduction

Diagnostic biochemistry, is a branch of laboratory medicine that focuses on the analysis of bodily fluids to diagnose and monitor diseases. This field plays a crucial role in understanding the biochemical mechanisms underlying various conditions, enabling accurate diagnosis, prognosis, and management. The biological samples for diagnosis include blood, urine, cerebrospinal fluid, pleural fluid and tissues.

Factors Affecting Serum Enzyme Activity or Protein Level

1. Organ Mass and Enzyme Tissue Concentration:

• Higher enzyme concentrations in organs can lead to greater increases in serum enzyme activity during disease. For instance, the liver’s large mass contributes to potential increases in serum ALT activity.

2. Cell Location

• The proximity of cellular enzymes to the blood, urine, or other fluids determines the fluid in which an enzyme’s activity will increase upon cell injury. For example, renal tubular gamma-glutamyltransferase (GGT) is released into urine, not blood, following injury.