Microorganisms: Infectious Disease and Ecology

Blog entries about bacteria, viruses, fungi and other microorganisms.

PROTAC Virus Vaccines: A New Approach to Vaccine Development

Posted on by Michele Arduengo

Vaccine research and development is a major area of focus for life scientists across the globe. Clinical trials have shown that vaccines that target tumors show promise for cancer treatment. Additionally, the emergence of new zoonotic diseases has revealed a need to develop vaccines quickly as the world becomes more global and human populations interact more often with each other and wild habitats. Importantly, these vaccines need to be suitable for distribution in a variety of settings, including those that do not have easy access to refrigeration.

Influenza Virus. Si et al used influenza as a model to engineer and test PROTAC Virus vaccines

There are many ways to classify the different types of vaccines that are currently available. The National Institute of Allergy and Infectious Diseases in the United States, categorizes vaccines as: whole pathogen vaccines, subunit vaccines, and nucleic acid vaccines—based on how the antigen that stimulates the immune response is delivered to the host.

Whole-pathogen vaccines, which include many of vaccines used in clinical settings, use the entire pathogen (organism that causes the disease) that has been either weakened or killed to elicit a protective immune response. Killed vaccines are what their name implies: the pathogen has been killed so that it cannot cause disease, but enough of its structure remains to generate antibody response. Often, the immune response generated with killed vaccines is not as robust as that generated with other kinds of vaccines. 

Weakened or attenuated vaccines use whole pathogens that have been weakened in the laboratory through long-term culture or other means. Our modern MMR (measles, mumps and rubella) vaccine is an example of an attenuated vaccine. These vaccines tend to generate strong, long-lasting immune responses, but have increased risk for immunocompromised individuals.

Engineering an Influenza A PROTAC Virus Vaccine

A recent paper by Si et al published in Nature Biotechnology describes a new type of live-attenuated whole pathogen vaccine: the PROTAC virus. PROTAC viruses are prevented from replicating by targeting critical viral proteins for degradation using the host cell protein degradation pathway. The vaccine is live-attenuated by the host cells that degrade critical proteins.

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Detecting SARS-CoV-2 In Wastewater: The New Frontier in Pandemic Surveillance

Posted on by AnnaKay Kruger

Tracking the spread of COVID-19 has been a tremendous challenge throughout the pandemic, but doing so is a key step toward containing the virus. Many communities have relied on patient testing and contact tracing, with limited success. In search of better methods, some countries have made inroads in a different form of disease surveillance: wastewater-based epidemiology (WBE). This approach involves testing wastewater for the presence of pathogens, primarily through DNA and RNA analysis, and has proved to be an accurate and highly effective way to keep tabs on the prevalence and progression of COVID-19 at the population level.

Switzerland is among those countries that have implemented WBE in their efforts to stay ahead of the pandemic. Since WBE first emerged in 2020 as a promising tool, several Swiss laboratories undertook wastewater testing, and protocols were established early.

“At the beginning, the methods to actually detect coronavirus in wastewater were rather laborious and complicated, and involved a lot of resources,” said Dr. Claudia Bagutti, microbiologist and molecular biologist in the State Laboratory of Basel-City, Switzerland.

Bagutti heads a small team performing applied biosafety research. In 2020, her lab was tasked with developing an assay for detecting COVID-19 in wastewater. However, the available methods were prohibitively complex and resource intensive.

In the meantime, researchers at Promega recognized that Promega products and methodologies could potentially be applied to WBE and set to work developing simpler and more efficient method for wastewater analysis. In the spring of 2021, Bagutti’s team decided to try adopting this method.

“Promega had a very nice method which was less laborious and much easier to handle, and that’s why we gave it a try,” said Bagutti.

In the ensuing study, Bagutti and her team analyzed effluent from the catchment area of one municipal wastewater plant in Switzerland. They examined the total wastewater output of around 270,000 people. Viral RNA was extracted using Promega’s Maxwell® RSC Environ Wastewater TNA Kit. The number of RNA copies present, representing the overall concentration of COVID-19 in each sample, was determined via quantitative reverse transcriptase (RT-qPCR) using the GoTaq® Enviro Wastewater SARS-CoV-2 Systems, also from Promega. The viral RNA was subsequently sequenced with next generation sequencing, and the results correlated quite well with the COVID-19 cases in the catchment area. Remarkably, this study detected the Omicron variant in a wastewater sample one day prior to the first reported case identified through patient testing.

“We observed a similar spread to most other western countries with respect to the time of the first discovery of these variants,” said Bagutti. “We were also able to demonstrate the presence [of Omicron] in the wastewater before it came up in a sample of a COVID-19 patient test, which of course shows the usefulness of wastewater monitoring for the prediction of new variants and infection dynamics.”

WBE is especially promising in that it provides population-level data independent of patient testing. Health departments can be alerted to the presence of COVID-19 earlier than would otherwise be possible with traditional testing and can take precautions to contain the spread. In creating a more user-friendly method for wastewater analysis, Promega has opened the door for more laboratories to conduct WBE, which could provide communities around the world with the information they need to preempt the progression of COVID-19.

“The Promega method is very straightforward to handle,” said Bagutti. “It only takes a small volume of wastewater, which makes it handy. It’s less time-consuming compared to the methods which were in the literature at the beginning of the pandemic, and it just works very well. We also did experience great support from Promega.”

At this point, much of the wastewater analysis performed in Switzerland is done with the Promega method, including in federal, state or private labs. The swift advance of WBE in Switzerland speaks to the colossal effort put forth both by Promega researchers in developing the necessary products and methodologies, as well by those labs that have made use of Promega’s products to monitor COVID-19 in wastewater.

“It’s really been a success story for us, from the beginning,” said Bagutti.

Learn more about Promega’s work with wastewater-based epidemiology.

New Assay to Study SARS-CoV-2 Interaction with Human ACE2 Receptor

Posted on by Promega

Severe acute respiratory syndrome (SARS) is a viral respiratory disease caused by a SARS-associated coronavirus. The most recent version, SARS-CoV-2 was first detected in China in the winter of 2019 and is responsible for the current COVID-19 (coronavirus disease 2019) global pandemic. This virus and its variants have resulted in over 200 million infections and more than 4 million fatalities world-wide. To combat this deadly outbreak the global research community has responded with remarkable swiftness with the development of several vaccines and drug therapies, all produced in record time. In addition to vaccines and drug therapies, diagnostic kits and research reagents continue to roll out to track infections and to help find additional therapies.

This peer-reviewed paper published in Nature Scientific Reports by Alves and colleagues demonstrates how a new assay can be used to discover novel inhibitors that block the binding of SARS-CoV-2 to the human ACE2 receptor as well as study how mutations in the SARS-CoV-2 Spike protein alter its apparent affinity towards human ACE2. The paper also details studies where the assay is used to detect the presence of neutralizing antibodies from both COVID-19 positive samples as well as samples from vaccinated individuals.

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Streamlining Research: The Merits of Adaptive Clinical Trials

Posted on by AnnaKay Kruger

Clinical trials are arguably the backbone of medical advancement. But the trials most worth doing are usually large, costly and time-intensive, demanding extensive resources and personnel. During the COVID-19 pandemic, there has been a marked uptick in the number of clinical trials, many of which are woefully flawed with issues ranging from insufficient sample size to bad design. The published research that follows is often redundant or inconclusive.

So how can scientists designing and running clinical trials streamline their efforts to reduce waste and achieve more useful outcomes? The answer could be adaptive clinical trials.

Adaptive clinical trials are designed so they can be modified as data are being collected
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A One-Two Punch to Knock Out HIV

Posted on by Sara Klink
This schematic of HIV life cycle summarizes years of research to understand HIV and get to a potential cure for HIV infection
HIV-1 lifecycle illustration. Copyright Promega Corporation.

Scientists investigating the human immunodeficiency virus (HIV) have learned much about the retrovirus’s lifecycle, but their ultimate goals were to discover a cure and prevent infection. In the decades since HIV was discovered, basic research and pharmaceutical drug development have expanded the antiviral toolbox, but these HIV treatments do not provide a functional cure, only manage the infection. However, two techniques may offer a potential cure for HIV infection using CRISPR and a possible vaccine using mRNA.

CRISPR-Based Therapy May Cure HIV Infection

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Seeing is Believing: How NanoLuc® Luciferase Illuminates Virus Infections

Posted on by Jordan Nutting
Artists interpretation of in vivo imaging of viral infections in mice using NanoLuc luciferase.

Wearing blue surgical gowns and white respirator hoods, research scientist Pradeep Uchil and post-doctoral fellow Irfan Ullah carry an anesthetized mouse to the lab’s imaging unit. Two days ago, the mouse was infected with a SARS-CoV-2 virus engineered to produce a bioluminescent protein. After an injection of a bioluminescence substrate, a blue glow starts to emanate from within the mouse’s nasal cavity and chest, visible to the imaging unit’s camera and Uchil’s eyes.

“We were never able to see this kind of signal with retrovirus infections.” Uchil is a research scientist at the Yale School of Medicine whose work focuses on the in vivo imaging of retroviral infections. Normally, the mouse would have to be sacrificed and “opened up” for viral bioluminescent signals from internal tissues to be imaged directly.

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From Drug Use to Viral Outbreaks, How Monitoring Sewage Can Save Lives

Posted on by Johanna Lee

Most of us, after we flush the toilet, don’t think twice about our body waste. To us, it’s garbage. To epidemiologists, however, wastewater can provide valuable information about public health and help save lives.

History of Wastewater-Based Epidemiology

Wastewater-based epidemiology (WBE) is the analysis of wastewater to monitor public health. The term first emerged in 2001, when a study proposed the idea of analyzing wastewater in sewage-treatment facilities to determine the collective usage of illegal drugs within a community. At the time, this idea to bridge environmental and social sciences seemed radical, but there were clear advantages. Monitoring wastewater is a nonintrusive and relatively inexpensive way to obtain real-time data that accurately reflects community-wide drug usage while ensuring the anonymity of individuals.

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Rice-Based Cholera Vaccine

Posted on by Riley Bell

Oral vaccines are a great strategy and are especially beneficial in areas with poor sanitation. This form of vaccine distribution could help control the acute diarrheal disease caused by Vibrio cholera. There are an estimated 1.3 to 4 million cases and 21,000 to 143,000 deaths from cholera each year. A recent study from The Lancet Microbe finds new hope in a rice-based cholera vaccine that will fight against the diarrheal toxin without severe adverse events.

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What You Should Know About The Delta Variant

Posted on by Jordan Villanueva

The Delta Variant poses a unique challenge to global health. We’ve compiled answers to some of the most common questions about Delta and other SARS-CoV-2 variants.

What is a variant?

A variant is a form of a virus that is genetically distinct from the original form.

“All organisms have mutation rates,” says Luis A Haddock, a graduate student at University of Wisconsin – Madison. “Unfortunately for us, viruses have one of the highest mutation rates of everything that currently exists. And even more unfortunately, RNA viruses have the highest mutation rates even among viruses.”

Luis works in the Friedrich Lab at UW-Madison, which has been sequencing SARS-CoV-2 genomes from positive test samples since the beginning of the pandemic. SARS-CoV-2 is constantly evolving, and sequencing can help us follow it through time and space. Most of the variants don’t behave any differently. A single nucleotide substitution might not even change the amino acid sequence of an encoded protein. However, occasionally a mutation will alter the structure or function of a protein.

Learn more about SARS-CoV-2 sequencing in the article “From Primate Models to SARS-CoV-2 Sequencing and Testing,” featuring David and Shelby O’Connor, two collaborators of the Friedrich Lab.

What is a Variant of Concern?

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How Promega Helped Our Lab Scale Up Drug Discovery for Bloodborne Pathogens

Posted on by Promega

This blog was written by Sebastien Smick, Research Technician in Dr. Jacquin Niles’ laboratory at Massachusetts Institute of Technology (MIT)

Our lab is heavily focused on the basic biology and drug discovery of the human bloodborne pathogen Plasmodium falciparum, which causes malaria. We use the CRISPR/Cas9 system, paired with a TetR protein fused to a native translational repressor alongside a Renilla luciferase reporter gene, to conditionally knock down genes of interest to create modified parasites. We can then test all kinds of compounds as potential drug scaffolds against these gene-edited parasites. Our most recent endeavor, one made possible by Promega, is a medium-low throughput robotic screening pipeline which compares conditionally-activated or-repressed parasites against our dose-response drug libraries in a 384-well format. This process has been developed over the past few years and is a major upgrade for our lab in terms of data production. Our researchers are working very hard to generate new modified parasites to test. Our robots and plate readers rarely get a day’s rest!

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