Virus laboratory

The virus is likely a live vaccine that escaped from the Chinese laboratory before it could be engineered into a less dangerous state, he added. Murphy said, adding that initial escape took place in August Murphy stated. The document also discloses the identity of a U. Amid heightened tensions over a possible second Russian invasion of Ukraine, federal security agencies warned this week that Moscow could conduct cyberattacks against critical U.

The three agencies stated that Russian intelligence agencies, the civilian SVR and military GRU, have formidable cyberattack capabilities and have demonstrated their prowess in the past. Past victims include defense industrial networks, health care providers, energy and telecommunications companies and government networks.

Russian-based hackers also launched a major energy sector intrusion campaign from to Sophisticated Russian hackers use common but effective tactics to break into networks used by the 16 infrastructure systems considered critical, including computer systems linking energy, communications, transportation, finance, manufacturing, water, health care and food sectors.

Initial access for the attacks may be attempted through several virtual private networks, Cisco routers, Oracle servers, Citrix software, Microsoft Exchange and several other known avenues of attack. Industrial control systems used to operate the electric grid, dams and nuclear power plants also could be attacked by the Russians.

Past industrial control attacks linked to Moscow have included the Havex Trojan, which hit systems in the United States, Spain, France, Italy, and Germany beginning in ; and the cyberattacks against Ukrainian power companies that caused blackouts throughout the country.

Analysts say new outbreaks in several locations could derail the controversial upcoming Winter Olympics set for Beijing next month. Many similar viruses are found in wild bats, and it seems likely that is the origin of this one, probably via an intermediate host.

The lab-leak hypothesis usually points the finger at the Wuhan Institute of Virology, which is close to the Huanan Seafood Market , where the first major cluster of infections occurred. The institute has a long history of collecting and analysing bat coronaviruses. Basic Research. Leprosy Hansen's Disease. Lyme Disease. Antibiotic Treatment. Chronic Lyme Disease. Featured Research. Types of PIDDs. Talking to Your Doctor. Therapeutic Approaches. Animal Prion Diseases and Humans.

Rocky Mountain Spotted Fever. Schistosomiasis Bilharzia. Tickborne Diseases. Tuberculosis Drugs. West Nile Virus. Addressing Zika Virus. Types of Funding Opportunities. See Funded Projects. Sample Applications. Determine Eligibility. Prepare Your Application. Additional Application Elements. Research with Special Considerations. Submit an Application. Track Your Application.

Understand the Review Process. Respond to Pre-Award Requests. After Award. Contract Solicitations. Contact the Office of Acquisitions. Most Recent Edition. Browse by Edition Date. Search All Funding News. Each may be chosen as highly specific for a particular virus strain or, alternatively, to represent consensus sequences within a gene known as conserved within a given family or genus.

By probing for a conserved gene, such as that for RNA polymerase, it is even possible to discover a previously unknown agent. Reactions must be carried out under very carefully controlled conditions of ionic strength, temperature, primer concentration, and nucleotide concentration.

Deviations can result in non-specific amplification. PCR technology has undergone numerous major developments since its first description in These include:. Use of the heat-stable DNA polymerase Taq of Thermus aquaticus , an organism naturally found in hot springs. Since this makes it no longer necessary to replenish the enzyme between cycles, the reaction tubes can remain sealed, and it also allows the use of higher annealing temperatures thereby increasing reaction specificity by reducing false-positive reactions due to mismatching;.

This can greatly increase sensitivity, albeit at the potential cost of increasing the risk of false- positive reactions;. Due to the detection of trace amounts of DNA sequence with extreme sensitivity, early PCR results suffered from regular problems of environmental contamination with DNA products leading to false-positive results. The procedure developed a reputation for unreliability, and laboratories went to heroic efforts to prevent reaction contamination, including stringent physical segregation of the different steps in the procedure.

This has become far less of a problem with recent advances, in particular the use of real-time detection methods;. Real-time PCR testing. This method for detecting PCR products required the development of a thermocycler with an inbuilt fluorimeter allowing measurement of newly synthesized PCR products in the reaction tube as were accumulating, that is, in real time. The reaction products can be detected by dyes that fluoresce when bound non-specifically to any double-stranded DNA, for example, SYBR Green; or by sequence-specific reporter probes EgTaqMan containing a fluorescent reporter at one end and a fluorescence quencher at the other, that bind specifically to newly synthesized target sequences leading to loss of quenching and emission of a quantitative fluorescence signal.

As the reaction progresses, the intensity of the fluorescent signal is continually monitored and plotted, generating curves the position of which reflects the original concentration of target. This approach has largely replaced other methods for product detection because it does not require the reaction tube to be opened once the reaction has started, thereby minimizing contamination, it achieves excellent quantitative measurements, is more sensitive than earlier detection systems, and if a sequence-specific reporter probe is used it has improved specificity because only the target sequence and no other non-specific DNA molecules is detected;.

Development of more accurate quantitation. Real-time detection methods allow generation of standard curves the position of which corresponds to the original concentration of target, and an unrelated copy number control can be included in the reaction to detect any non-specific inhibition of the enzyme reaction. Use of multiplex PCR.

Once different fluorescent probes became available for PCR product detection, it became possible to include different sets of primers bearing different fluorescent labels for different targets in the same reaction, and thereby to detect a number of different products simultaneously. This is exploited in a number of standard protocols for specific sites, for example, respiratory virus infections Fig. A TaqMan probe chemistry mechanism.

B Real-time quantitative PCR data. Reaction curves for a test run are used to assess assay conditions, using dilutions of an RNA transcript copy number control of a cloned segment of canine pneumovirus. The vertical lines represent the Ct value, which is the number of PCR cycles required for the fluorescent signal to cross the threshold value. These methods have the potential advantage in being extremely fast and do not require thermal cycling equipment.

Several examples are available as approved diagnostic tests. Due to the speed, sensitivity, and versatility of PCR methods for detecting and quantifying viral genomes, this approach is now a significant part of the routine work of the diagnostic laboratory, and many commercial test systems are available. Methods such as antigen detection and virus isolation tend to require different reagent preparation expertise and methods specific for each individual virus, whereas PCR technology is more universally applicable because its specificity relies primarily on the chosen primer sequences.

The procedure is invaluable when dealing with 1 viruses that cannot be cultured satisfactorily, 2 specimens that contain predominantly inactivated virus, as a result of prolonged storage or transport, 3 where quantitative results are needed, or 4 to avoid exposing laboratory staff to culturing larger quantities of a biohazard category 3 or 4 agent.

Furthermore, it is easy to make new PCR reagents for new viruses, and thereby rapidly expand the capacity for testing. Problems that may be encountered with PCR include 1 some clinical samples that may contain factors that inhibit the activity of the DNA polymerase, leading to falsely low or negative results.

Another technological advance that is impacting the field of diagnostics is the use of microarrays or microchips for nucleic acid detection. These oligonucleotides can represent conserved sequences from virtually all viruses represented in the various genetic databases, or can be customized to represent only viruses from a given specific disease syndrome, such as acute respiratory disease in children.

The basis of the technology is the capture by these oligonucleotides of randomly amplified labeled nucleic acid sequences from clinical specimens. The binding of a labeled sequence is detected by laser scanning of the chip and software programs that assess the strength of the binding. From the map position of the reacting oligonucleotides, the software identifies the virus in the clinical sample. This type of test was used to initially determine that the virus responsible for severe acute respiratory syndrome SARS was a coronavirus.

With knowledge of the oligonucleotide sequences that bind an unknown virus, primers can be made to eventually determine the entire nucleotide sequence of the virus. The low cost of oligonucleotide synthesis, development of laser scanning devices, nucleic acid amplification techniques, and software development have made this technology available in specialized reference laboratories, increasingly more common in national diagnostic laboratory networks.

Microarray technology has been used as a research tool for some years, for example, for studying comprehensive gene expression in cells and tissues. It is now being applied increasingly for monitoring host responses to infections and for assessment of the development of antiviral drug resistance.

It has been used to map immune response gene expression in hepatitis C-infected liver tissue, and changes in leukocyte gene expression in patients with sepsis. It is now also being directly applied in the diagnostic arena. For example, commercial microarrays are available for the simultaneous detection of a large panel of respiratory viruses, by reacting the product of a multiplex PCR and RT-PCR reaction with a solid chip or liquid bead platform carrying oligonucleotide probes for multiple viruses.

Similar approaches have been described for the simultaneous detection and typing of human papillomavirus sequences in routine clinical specimens. The transfer of this technology to the routine diagnostic laboratory still presents challenges, not least due to the requirements for a rapid turn-around, high-throughput, quality-assured procedure for the diagnostic setting, and the unpredictability and heterogeneity of clinical samples.

Nevertheless it is likely that application of microarray technology will eventually lead to another transformation of the diagnostic laboratory.

A number of systems are commercially available, the approach has yielded enormous benefit in various research fields, and its application to diagnostic virology is now being explored. Different platforms have different advantages and pitfalls, for example, differences in read length and read depth, and access to a capable bioinformatics resource is essential to ensure that data analysis can be done appropriately.

For an unbiased or broad-based analysis, all nucleic acids in a clinical sample can be sequenced on a multiplex platform; however, because host sequences can frequently outnumber infecting virus sequences by 10 5 or more, prior selective enrichment of virus sequences can be achieved, for example, by hybrid capture using PCR-derived capture probes, by prior PCR amplification of suspected virus sequences in the unknown target sample, or by physical methods of partial purification, for example, based on the nuclease resistance of encapsidated viral genomes.

Discovering new pathogens in undiagnosed illness or outbreaks e. Retrospective diagnosis of undiagnosed illness, for example, encephalitis, using stored autopsy samples;. Analysis of the quasi-species sequence composition of the viruses in a clinical sample, including detection of minor variants with new pathogenic implications, for example, drug resistance;. Full application of deep sequencing technology to virus diagnosis has not yet been achieved, and deep sequencing methods are likely to complement existing methods rather than replace them.

Costs have plummeted enormously, now allowing the technology to move from large institutions to the more widespread diagnostic setting. However many development challenges remain, including the huge computing and data analysis requirements that are created by the generation of enormous amounts of data. Newer techniques, particularly sensitive antigen EIAs and PCRs, do not suffer from the drawbacks of virus isolation that included high cost, slowness, false negatives due to virus being inactivated during transport or complexed with antibody, cell lines losing sensitivity, and increased concerns about live virus transmission to staff.

Many diagnostic laboratories no longer try to isolate viruses in cell culture; virus isolation in cell culture is mostly limited to research laboratories or where there is a need to grow up large amounts of virus.

Even bulk antigen production is now often done preferentially by expression of recombinant antigens, and unknown agents can be sought using molecular techniques such as random-priming PCR. Samples may need preparation by treatment with antibiotics, clarification of debris, or disruption of mucus. Specially designed cell lines may express particular virus receptors to broaden specificity or indicator systems for easier detection of the presence of virus.

Evidence that a new virus has been isolated may come from routine reading of monolayers for cytopathic effects CPEs , which may be distinctive for a particular virus. Alternatively, monolayers may be screened by a variety of techniques including antigen staining, hemadsorption, electron microscopy, or PCR.

Blind passage of material not showing a CPE may be advisable to identify slow-growing agents, and regular comparison with uninoculated control cells is essential to distinguish viral CPE from degeneration of uninfected cell monolayers.

Finally, a variety of methods may be needed to obtain final identification of the virus that has been isolated, sometimes including detailed strain identification or sequencing. Cytopathic effect of viruses in cell cultures. A Confluent monolayer of uninfected Vero cells. Massive cytopathic effect CPE , with cells rounded up and detaching from the substrate. C Confluent monolayer of uninfected Vero cells. D Vero cells infected with herpes simplex virus 1 HSV-1 at 24 hours post-infection.

Since most diagnostic specimens contain a much lower titer of infectious virus, CPE is usually more asynchronous, beginning with few foci involving few cells and taking longer to achieve widespread infection. Phase contrast microscopy C, D monochromatic green light provides slightly better resolution. For most routine diagnostic purposes it is usually not necessary to determine the exact strain or sequence of the virus that has been detected.

On the other hand, there are certain situations when this information can be crucial for patient management, or for epidemiological or public health purposes. Serological methods including EIAs and neutralization of virus growth can be used to identify different serotypes, assisted by the availability of appropriate monoclonal antibodies Fig. Different influenza virus isolates are characterized and compared by comparing hemagglutination-inhibition titers using standard antisera.

Virus neutralization, as exemplified by the interactions of neutralizing antibodies with human rhinovirus A The normal route of infection. The virus attaches to the ICAM-1 receptor and enters by endocytosis.

As the internal pH of the endosome decreases, the particle uncoats and releases its RNA genome into the cytoplasm. B Possible mechanisms of neutralization of the virus by antibodies. At least five mechanisms of neutralization have been supported by experimental evidence: 1 blocked attachment—binding of antibody molecules to virus results in steric interference with virus-receptor binding, 2 blocked endocytosis—antibody molecules binding to the capsid can alter the capsid structure, affecting the process of endocytosis, 3 blocked uncoating—antibodies bound to the incoming particle fix the capsid in a stable conformation so that pH-dependent uncoating is not possible, 4 blocked uncoating inside the cell—antibodies themselves may be taken up by endocytosis and interact with virions inside the cell after infection starts, 5 aggregation—because all antibodies are divalent, they can aggregate virus particles, facilitating their destruction by phagocytes.

Any or all of these mechanisms may operate in quantitative neutralization assays. Virus neutralization assays may be used to measure the titer of neutralizing antibody in clinical samples, by reacting a standard virus inoculum with different dilutions of serum.

There are many other variations, for example, known antisera to different virus serotypes may be used to identify the serotype of a new virus isolate; tests may be run in cell cultures with cytopathic effect or plaque endpoints, or in animals when necessary, and many steps may be automated.

Complete nucleotide sequencing of a viral genome is not often attempted for diagnostic purposes at present although it probably will be increasingly widespread over the next few years. However, obtaining a partial sequence from PCR products is widely used and has replaced earlier molecular approaches such as restriction mapping of DNA products and oligonucleotide fingerprinting. Because different rabies virus sequence variants have segregated according to geographical region and animal host species, sequencing of rabies virus recovered from a patient can be used to determine the origin of the infection.

In order to investigate an apparent cluster of HIV patients who may or may not have acquired their infection from a common source, for example, a single medical practice or surgeon or a common sexual partner, partial sequences of their viruses can be compared with the usual random sequence variation seen in that population, to assess the likelihood that this truly represents common source infection.

The identification of unknown viruses or viral antigens using panels of antibodies of known specificity has already been discussed. Any of the above serological techniques may be employed the other way around, using panels of known antigens to identify unknown antibodies. The basic principles of those most widely used today are set out in Table Hemagglutination inhibition HI test for detecting antibodies specific for influenza virus H3N8, one of the highly pathogenic viruses that are of concern should these gain increased human-to-human transmissibility capability.

Sera are A treated to remove non-specific agglutinins and non-specific inhibitors of agglutination. B Treated sera are serially diluted twofold in buffered saline in rows of wells of well microtiter plates. C A volume of influenza virus containing 4 hemagglutinin units is added to each well and plates are incubated for 30 minutes.

D A standard volume of turkey red blood cells 0. E The plates are incubated and read when control wells show complete red blood cell settling button. Where virus agglutinates the erythrocytes, these form a shield pattern; however, where enough antibody is present to coat the viral HA, hemagglutination is inhibited, and the erythrocytes settle to form a button on the bottom of the cup.

Rows A , B : Titration of the influenza virus used in the test, confirming that the correct amount 4 units has been added to test wells. Row C : Red blood cell control. Rows D—H : Serially diluted test sera, with the first well in each row serving as a serum control for non-specific hemagglutination.

Results: HI titers are the reciprocal of the last dilution of the serum showing inhibition of agglutination by test virus. Blood is collected in the absence of anticoagulants and given time to clot, and then the serum is separated. Acute and convalescent serum samples should be tested simultaneously. Prior treatment of the serum is not generally required for assays that simply measure antigen—antibody binding, such as EIA, RIA, Western blot, latex agglutination, immunofluorescence, or immunodiffusion.

The paired sera are then titrated for antibodies using any of a wide range of available serological techniques. In practice, there are many subtleties in the interpretation of results. For example, the timing of the collection of the paired sera in relation to the date of onset of illness must be carefully assessed to allow for inappropriate sample timing.

Moreover, an individual with immunity due to prior infection or immunization may undergo a second or reinfection, often of a subclinical nature, but showing a rise in antibody titer. It is obvious that in reality, two well-timed paired sera to allow demonstration of a four-fold rise in titer, are often not available. Attempts are sometimes made to infer that a recent infection has occurred, on the basis of one serum sample containing a relatively high antibody titer; indeed laboratories may issue guidelines about what titer of antibody in a single serum may imply recent infection.

In practice this is often unreliable, as the peak antibody titer seen in the convalescent stage of an infection can vary significantly from person to person.