Virology, Emerging Diseases & vaccines

Influenza and acute respiratory virus disease is a field of public health of major international importance.  Recent epidemiological events - the 2009 pandemic of H1N1 influenza, first identified in Mexico; the occurrence of human cases of avian influenza A(H7N9) in China; the emergence of Middle East Respiratory Syndrome (MERS-CoV); and ongoing outbreaks of virulent avian influenza A(H5N1) in several countries; continue to highlight the requirement for international collaboration on respiratory virus research and development.  Acute respiratory infections (ARI) impose a significant burden of both morbidity and mortality on children worldwide. In 2000 alone, an estimated 1·9 million children under the age of five died as the result of ARI, accounting for 14% of total mortality in the age group. While most infections are fairly mild, self‐limiting, and confined to the upper respiratory tract, severe illnesses can also occur. Influenza infections can be life‐threatening, mainly among the elderly, yet present a risk for the entire human population in the wake of influenza pandemics. As a result of constant genetic mutations in the influenza virus, the effectiveness of vaccination depends on the continuous monitoring of circulating strains globally.

Viral transmission is the process by which viruses spread between hosts. It includes spread to members of the same host species or spread to different species in the case of viruses that can cross species barriers. Transmissibility within human populations is a key determinant of epidemic potential. Many viruses that can infect humans are not capable of being transmitted by humans; most human transmissible viruses that emerge already have that capability at first human infection or acquire it relatively rapidly. Virus transmission to humans occurs via inhalation of aerosolized virus-contaminated rodent urine, saliva, and feces, rarely by rodent bites. Humans are usually considered as a dead-end host that does not transmit the virus further. For plant viruses, the pathways reviewed are vertical and horizontal transmission via pollen, and horizontal transmission by parasitic plants, natural root grafts, wind-mediated contact, chewing insects, and contaminated water or soil. For insect viruses, they are transmission by plants serving as passive “vectors,” arthropod vectors, and contamination of pollen and nectar.

Viral pathogenesis is the study of the process and mechanisms by which viruses cause diseases in their target hosts, often at the cellular or molecular level. It is a specialized field of study in virology. Pathogenesis is a qualitative description of the process by which an initial infection causes disease. Viral disease is the sum of the effects of viral replication on the host and the host's subsequent immune response against the virus. Viruses are able to initiate infection, disperse throughout the body, and replicate due to specific virulence factors.

An infection occurs when a microorganism enters a person's body and causes harm. The microorganism uses that person's body to sustain itself, reproduce, and colonize. These infectious microscopic organisms are known as pathogens, and they can multiply quickly. Examples of pathogens include: bacteria.

Clinical Virology incorporates a spectrum of disciplines and information ranging from the X-ray crystallographic structure of viruses and viral proteins to the global socio-economic impact of disease. It encompasses events that include accounts ranging from epidemics impacting history to the identification of new agents and mechanisms of disease. Viruses are important pathogens of the nervous system.

Viral oncology is a subdivision of oncology, in these it is concerned with treatment of human cancers /tumours with virus particles. Viruses have long been used as tools to understand basic mechanisms of cancer development and progression. Many cellular proteins crucial in oncogenesis and tumour suppression were first discovered by studying tumour viruses. Approximately 20% of all cancers worldwide results from chronic infections, in specific, up to 15% of human cancers is characterized by a viral aetiology with higher incidence in Developing Countries. Certainly, the infectious nature of specific tumours has important implications in their prevention, diagnosis, and therapy. In the 21st Century, the research on viral oncology field continues to be dynamic, with new significant and original studies on viral oncogenesis and as a translational research from virology for the treatment of cancer. At present, only seven established human tumour viruses are known which include Epstein-Barr Virus (EBV), Human Papillomavirus (HPV), Hepatitis B and C viruses (HBV and HCV), Human T-cell lymphotropic virus-1 (HTLV-1), Human Herpesvirus-8 (HHV-8), and Merkel Cell Polyomavirus (MCPyV)., but numerous human cancers are suspected to have an infectious etiology that has not yet been identified. Discovery of each human tumour virus has spawned a new research field that has contributed to our understanding of infectious tumours and cancer biology.

Antiviral therapy is one of the most exciting aspects of virology, since it has successfully employed basic science to generate very effective treatments for serious viral infections. Most drugs and vaccines, however, selectively target a single virus, thereby providing a “one drug-one bug” solution. In contrast, broad-spectrum antivirals (BSAs) can cover multiple viruses and genotypes and reduce the likelihood of development of resistance. Therefore, some BSAs can be used for the rapid management of new or drug-resistant viral strains, for a first-line treatment. There are two types of anti-viral therapies depending on the type of virus, they are: "episodic" oral antiviral therapy (where antiviral therapy is used intermittently by the patient during a recurrence), or "suppressive" antiviral therapy (where the antiviral therapy is taken continuously to prevent recurrences).

HIV is a sexually transmitted infection, but it can progress to a disease called acquired immunodeficiency syndrome (AIDS) when HIV infection is untreated. Other examples of STDs are chlamydia, gonorrhea, human papillomavirus (HPV) infection, and syphilis. Having an STD can make it easier to get HIV.

Human endogenous retroviruses (HERVs) represent footprints of previous retroviral infection and have been termed “fossil viruses”. These viruses are spread through vertical transmission via the germline DNA. The role of HERVS in disease is not well understood. They may play a role in human cancers and autoimmune disease. While in baboons and mice there are ERVs that are transmissible as infectious viruses, this is not the case in humans. Human Endogenous Retroviruses (HERVs) may be triggers of autoimmune rheumatic disease. Most endogenous retroviruses are silent—the genes that they encode are not expressed or are expressed only under restricted conditions, although in some animals one or more endogenous retroviruses are normally expressed during the lifetime of an animal.

Viral genetics is the study of the mechanisms of heritable information in viruses, including genome structure, replication and genetic change. Viruses have been engineered as vectors for gene expression, vaccine development, and gene therapy. Viral genomes encode gene products that modulate host defences, including the immune response, an elaborate system that evolved in large part to protect us against invading microorganisms like viruses. Ideally, pathogens are cleared by immune defences with minimum damage to the host. However, in the process, the immune defences themselves can also cause damage (immunopathology). Viral evolution refers to the heritable genetic changes that a virus accumulates during its life time, which can arise from adaptations in response to environmental changes or the immune response of the host. Because of their short generation times and large population sizes, viruses can evolve rapidly. RNA viruses have high mutation rates that allow especially fast evolution. An example is the evolution of drug resistance in HIV.  Viruses are believed to have played important roles in the evolution of cellular organisms. Though viruses aren’t technically living – they need a host organism in order to reproduce – they are subject to evolutionary pressures. The recent development of potent antiviral drugs not only has raised hopes for effective treatment of infections with HIV or the hepatitis B virus, but also has led to important quantitative insights into viral dynamics in vivo. Viral dynamics include virus population dynamics, the role of the immune system in limiting virus abundance, the dynamics of viral drug resistance.

Molecular virology refers to the study of viruses at the molecular level which involves the analysis of genes and gene products of viruses and study their interaction with host (human, plant or animal) cellular proteins. Structural Virology is the molecular mechanism used by viruses to invade host cells establish an infection and ensure that progeny virus particles are released into the environment, all while evading the host's immune defences. Viruses are the smallest self -replicating organisms. Even though individually viruses are rather simple, as a group they are exceptionally diverse in both replication strategies and structures. Many viruses are important human pathogens.

To study the life cycle of human virus, we use various technologies like X-ray crystallography, cryo-electron microscopy. We investigate macromolecular interactions associated with virus cell entry, genome replication, assembly, and maturation. Viruses are very simple enough that we can aspire to understand their biology at a molecular level. Our efforts are directed towards using structural information for the development of anti-viral drugs and vaccines.

Solid organ and hematopoietic stem cell transplant recipients are uniquely predisposed to develop clinical illness, often with increased severity, due to a variety of common and opportunistic viruses. Patients may acquire viral infections from the donor (donor-derived infections), from reactivation of endogenous latent virus, or from the community. Herpes viruses, most notably cytomegalovirus and Epstein Barr virus, are the most common among opportunistic viral pathogens that cause infection after solid organ and hematopoietic stem cell transplantation. The polyoma BK virus causes opportunistic clinical syndromes predominantly in kidney and allogeneic hematopoietic stem cell transplant recipients. Hematopoietic stem cell transplantation is the treatment of choice for many hematologic malignancies and genetic diseases. However, viral infections continue to account for substantial post-transplant morbidity and mortality. While antiviral drugs are available against some viruses, they are associated with significant side effects and are frequently ineffective.

Rhabdoviruses are a diverse family of single stranded, negative sense RNA viruses that infect a wide range of hosts, from plants and insects, to fish and mammals. The Rhaboviridae family consists of six genera, two of which, cytorhabdoviruses and nucleorhabdoviruses, only infect plants. Novirhabdoviruses infect fish, and vesiculovirus, lyssavirus and ephemerovirus infect mammals, fish and invertebrates. The family includes pathogens such as rabies virus, vesicular stomatitis virus and potato yellow dwarf virus that are of public health, veterinary, and agricultural significance.

Viral immunology is simply the study of immune responses to viruses. A prolonged tissue-damaging effect resulting from an immune reaction against viruses is considered immunopathology. Such situations most commonly involve persistent viruses, which are themselves often mildly cytodestructive in the absence of an immune reaction. Chronic tissue damage initiated by viruses can also result in development of an autoreactive and an occasionally oncogenic response

Vaccines are recognized worldwide as one of the most important tools for combating infectious diseases. Despite the tremendous value conferred by currently available vaccines toward public health, the implementation of additional vaccine platforms is also of key importance.  In this regard, recent work has been focused on vaccine delivery systems, as an alternative to injectable vaccines, to increase antigen stability and improve overall immunogenicity. The Mucosal Delivery, Intradermal Vaccination, novel design strategies of nanomaterial carriers for vaccine delivery.

• Advances in DNA Vaccines, TLRS and Combination Adjuvants

• Latest techniques and advancements in Vaccine delivery systems

• Nano patch Technologies

• Needle-free vaccine delivery

• Routes & Medical devices for vaccines delivery

• Transdermal Delivery of VaccinesVehicle, Mineral Salt & Bacteria Derived Adjuvants

Despite growing evidence of a connection between the microbiota and the immune system, its impact on immunity to vaccination remains poorly understood. Recent studies have demonstrated a profound impairment in vaccine-induced antibody responses during microbiota perturbation.

Immunization is the process whereby a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine. Vaccines stimulate the body’s own immune system to protect the person against subsequent infection or disease. In addition to the initial immunization process, it has been found that the effectiveness of immunizations can be improved by periodic repeat injections or "boosters." Immunization is a proven tool for controlling and eliminating life-threatening infectious diseases and is estimated to avert between 2 and 3 million deaths each year. Immunotherapy, also called biologic therapy, is a type of cancer treatment that boosts the body's natural defenses to fight cancer. It uses substances made by the body or in a laboratory to improve or restore immune system function. Immunotherapeutic agents use or modify immune mechanisms. Use of these agents is rapidly evolving. A number of different classes of immunotherapeutic agents have been developed such as Monoclonal antibodies, Fusion proteins, Soluble cytokine receptors, Recombinant cytokines, Small-molecule mimetics, Cellular therapies.

Vaccine‐induced immunity that is established in advance of virus infection relies primarily on adaptive immune responses for protective efficacy. Critically, vaccination depends on the properties of antigen recognition, activation, expansion, memory, trafficking and the multitude of specialist functions of lymphocytes. The extent to which vaccine‐induced immunity is successful also determines the spread and maintenance of a viral pathogen within a population. Viral vaccines have had profound and enduring consequences for human and animal health; the worldwide eradication of smallpox and rinderpest are testament to their outstanding contribution to modern society.

COVID-19 affects different people in different ways. Most infected people will develop mild to moderate illness and recover without hospitalization.