Tuesday, January 28, 2014

Human Coronavirus HKU1 - The New Common Cold?

More than 200 different viruses are known to cause the common cold.

The most common cold viruses include:

  • Rhinoviruses -- 10-40%
  • Coronaviruses -- 20%
  • Respiratory Syncytial Virus (RSV) -- 10%

I have been seeing a small spike in human coronavirus (HCoV-HKU1) lately (including one of our virologists) and I decided that it would be a good time write a bit about the virus in order to raise awareness among non-virologists out there.
Human coronavirus
HCoV-HKU1 contains the HE gene which distinguishes it as a betacoronavirus, which is the same genus as Severe Acute Respiratory Syndrome Virus (SARS-CoV). It was first identified in January of 2005 in two patients from Hong Kong. The initial patient was a 71-year old man who had been hospitalized with an acute respiratory distress and confirmed bilateral pneumonia. It is possible the man had contracted the virus in nearby (~23 miles) Shenzhen as he had recently (within the incubation period) returned from a trip there.

When I get nasopharyngeal (NP) or throat swabs sent to the health lab, especially during influenza season, our algorithm includes virus culture (Hep-2, Caco-2, HFS, MRC-5, RMK, BGMK, and MDCK cells), influenza PCR, and if influenza negative we use the Luminex Respiratory Virus Panel.
Bio-Rad Bio-Plex 200 Hardware for RVP
HCoV-HKU1 has not been found to be cultureable in any of the above cell lines; however we have noticed some “irregularities” with the cells in these samples. The HCoV-HKU1 samples have been influenza negative, and were identified using the RVP.

HCoV-HKU1 is most closely related to the mouse hepatitis virus (MHV).
Mouse with hepatitis...get it? :)
HCoV-HKU1 is a positive-sense, single-stranded RNA virus. Without getting into too much detail, this means the virus particle is similar to a human mRNA in the sense that its genome can immediately be translated into protein without going through intermediate steps.

A trace back analysis of SARS-CoV negative NP aspirates from patients with respiratory illness during the SARS-CoV pandemic in 2003, identified HCoV-HKU1 RNA in a sample from a 35-year-old woman with pneumonia, as well as 10 patients in northern Australia.

The first identified case in the Western hemisphere was discovered by clinical virologists (good people!) at Yale-New Haven Hospital in Connecticut. They conducted a study of 851 infants and children over a seven-week period from December 2001 to February 2002. The children were also tested for Human respiratory syncytial virus (RSV), parainfluenza viruses (1-3), influenza A and B, adenovirus, and human metapneumovirus. All 851 tested negative, but trace back analysis revealed two of the children tested positive for HCoV-HKU1.

Coronavirus have been very important in the last decade as sources of global emerging disease concerns. SARS-CoV was a pandemic that occurred between winter of 2002 and summer of 2003. Spread to at least 37 countries, there were 8200+ reported cases and at least 775 deaths.
Currently, Middle Eastern Respiratory Syndrome Coronavirus (MERS-CoV) is smoldering. Since spring of 2012 there have been 157 documented cases and 66 deaths. The situation is being closely monitored.

The CDC has put together a very nice FAQ about coronaviruses linked here.

Lance D. Presser has a PhD in Microbiology and Immunology and currently is a Public Health Laboratorian.

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Thursday, January 23, 2014

Arthritis Associated with Exposure to Mimivirus?

Microbe Mimicking Virus - Mimivirus
A recent manuscript published in the Journal of Virology (which unfortunately is behind a pay wall) suggests that exposure to collagen produced by mimiviruses can potentially cause arthritis.

The giant DNA viruses e.g. Acanthamoeba polyphaga mimivirus, express collagen-like proteins that are similar in many ways to human collagens. Mimivirus replication or infection of humans has not been shown, and mimiviruses typically replicate in amoebae, however this manuscript demonstrates that roughly 30% of health (non-rheumatoid arthritis patients) and 36% of rheumatoid arthritis patients display a serum IgG response against the mimivirus capsid protein suggesting an immune response. Furthermore, human antibodies exist that recognize mimivirus collagen, and were frequently found in persons with rheumatoid arthritis.

A mouse model was also used by the group to demonstrate the ability of mimivirus to elicit antibody responses to collagen. The group showed that viral collagen was encoded by open reading frame L71 which is present at the surface of mimivirus particles. Exposure to mimivirus collagens elicited the production of anti-collagen antibodies in DBA/1 mice. DBA/1 mice are a widely used mouse model for rheumatoid arthritis.

DBA/1 mouse - commonly used rheumatoid arthritis model

One of the flaws to this study is the exposure method. While I understand that this is probably the best/cheapest model available to the researchers, the mice were exposed to mimivirus collagens by intradermal injection with mimivirus protein extracts. More than likely this would not be the "typical" route of exposure. I would also venture to guess that the dose used is significantly higher than what would be seen normally.

Overall, I am skeptical of the study. This is definitely an "extraordinary claims require extraordinary evidence" scenario. I don't think the authors have done enough to say "our study shows that environmental exposure to mimivirus represents a risk factor in triggering autoimmunity to collagens." I do think that it MIGHT pose a risk factor, but even with this Journal of Virology paper, it remains pretty doubtful in my mind.

The difference between "blood sera from healthy human subjects and from rheumatoid arthritis patients indeed demonstrated that 30% of healthy-subject and 36% of rheumatoid arthritis sera recognized the major mimivirus capsid protein" while statistically significant and powered, is not enough (especially considering Bayesian logic, and other corollaries discussed by Dr. John Ioannidis, which I will discuss in a later blog post).

The other data "six percent of healthy-subject sera recognized the mimivirus collagen protein (L71), and 22% of rheumatoid arthritis sera were positive for L71" is again, statistically significant, but not enough to walk this out as a risk factor. Potentially...maybe.

I would recommend going back and getting some more mechanistic data first before claiming exposure as a risk factor.

Lance D. Presser has a PhD in Microbiology and Immunology and currently is a Public Health Laboratorian.

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Sunday, January 19, 2014

Heart Inflammation Linked to Lyme Disease in Three Deaths

A recent Morbidity and Mortality Weekly Report (MMWR) from the CDC discusses a recent outbreak of Lyme associated carditis. During November 2012 - July 2013, one woman and two men (age range 26-38) from states with high incidence of Lyme disease experienced sudden cardiac death. Diagnosis was confirmed post-mortem.

The three deaths were investigated by CT, MA, NH, and NY Public Health Departments, as well as the CDC. Donated corneas from two decedents had been transplanted to three recipients before the diagnosis of Lyme disease was established, but no evidence of disease transmission was found.

Death from Lyme carditis is extremely rare, however it should be considered in events of sudden cardiac death in patients from high-incidence Lyme regions.

Typical presentation of bull's eye rash associated with Lyme disease
Lyme disease is a systemic illness caused by Borrelia burdorferi, a spirochete transmitted by Ixodes tick species. There were approximately 30,000 confirmed and probable cases of Lyme disease reported in the United States in 2012, primarily from CT, DE, ME, MD, MA, NH, NJ, NY, PA, RI, VT, MN, and WI. Common manifestations include cutaneous (bull's eye rash), neurologic, and rheumatologic signs and symptoms. Lyme infections causing symptomatic infection of the heart is extremely rare, and will usually resolve with proper antibiotic therapy.

The detailed case reports of each of the three patients is available via the MMWR here. Briefly, it was found that two of the three patients had minor underlying heart conditions (hypertension, atherosclerosis, and Wolff-Parkinson-White syndrome which is a cardiac conduction abnormality) and did not present with the traditional bull's eye rash.

Two of the patients were found responsive, unfortunately the third patient had seen a physician one day prior to death and was prescribed clonazepam for anxiety (no EKG was performed, no antibiotics were prescribed).

Pathologically when observing Lyme associated carditis, diffuse, mixed, perivascular lymphoplasmacytic (primarily lymphocytes and plasma cells) infiltrates will be observed on examination of heart tissue. Immunohistochemistry, PCR, Warthin-Starry stain, Enzyme Immuno Assay, or and Western blot for bands at (23, 41, 58, and 66 kDa).

Adult deer tick - Ixodes scapularis
Lyme disease is a nationally notifiable disease and any suspected case of Lyme carditis should be reported to local or state public health authorities. Health-care providers should ask suspected Lyme patients about cardiac symptoms and obtain and EKG. Health-care providers should also ask patients with unexplained heart block about possible exposure to ticks.

Lance D. Presser has a PhD in Microbiology and Immunology and currently is a Public Health Laboratorian

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Wednesday, January 15, 2014

Trich or Treat?

Oh microbiology! Anytime it can be made visual is a win.

Today, going through the viral culture specimens, and we noticed something moving in one of the 24-well plates.  The sample was from a genital swab which most of the time means Herpes 1 or 2, but usually Herpes doesn't move (at least not visibly). 

What is trichomoniasis?

Trichomoniasis (or “trich”) is a very common sexually transmitted disease (STD) that is caused by infection with a protozoan parasite called Trichomonas vaginalis. Although symptoms of the disease vary, most women and men who have the parasite cannot tell they are infected.

How common is trichomoniasis?

Trichomoniasis is considered the most common curable STD. In the United States, an estimated 3.7 million people have the infection, but only about 30% develop any symptoms of trichomoniasis. Infection is more common in women than in men, and older women are more likely than younger women to have been infected.

Lance D. Presser has a PhD in Microbiology and Immunology and currently is a Public Health Laboratorian

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Saturday, January 11, 2014

55% Efficacy of FluLaval Quadrivalent in Children Ages Three to Eight

A recent clinical trial published in the New England Journal of Medicine shows 55% efficacy of GlaxoSmithKline's FluLaval Quadrivalent influenza vaccine in protecting children ages three to eight. 55% efficacy is similar to previous findings for trivalent vaccines.

The trial also suggests that the vaccine can prevent children against "moderate to severe" flu, with an efficacy of more than 70% in those cases.

One of the main questions remains about the quadrivalent vaccine; whether or not it can protect against influenza B. The 2012-13 influenza season was exacerbated by a late surge of influenza B infections. The trivalent vaccine contains two strains of influenza A and one strain of influenza B. Whereas, the quadrivalent vaccine contains two A and two B strains. Hopefully by next spring/summer there will be enough data to draw conclusions on how effective the quadrivalent vaccine was against influenza B.

The trial was sponsored by GSK, which achieved US Food and Drug Administration (FDA) approval of FluLaval Quadrivalent in August 2013. The company also makes a second 4-strain flu vaccine, Fluarix Quadrivalent.

5,220 Children in Eight Countries
The trial was conducted at 15 centers in Bangladesh, the Dominican Republic, Honduras, Lebanon, Panama, the Philippines, Thailand, and Turkey. The authors recruited 5,220 children from ages three to eight and assigned them to receive the Quadrivalent Influenza Vaccine (QIV) or a hepatitis A vaccine as a control.

The QIV targeted influenza A/H1N1 (2009) and A/H3N2 as well as the two B strains. The QIV group consisted of 2,584 children and the control group of an equal number. Members of the treatment group received one or two doses, depending on their vaccine priming status. 

Recruitment of the children began in December 2010, and the authors conducted active and passive surveillance for flu-like illness for at least six months, through the end of October 2011. The trial's primary end point was influenza A or B confirmed by quantitative real-time polymerase chain reaction (qRT-PCR). As secondary end points, the authors used PCR-confirmed moderate-to-severe flu and PCR-positive, culture confirmed flu. Moderate-to-severe illness was defined as a body temperature above 39 degrees C, acute otitis media, lower respiratory tract illness, or serious extrapulmonary complications.

As for safety, the report says there were no notable differences between the QIV group and the control group, except that pain at the injection site was more common in the QIV group (47.7% versus 34.8%)

The authors note that there is limited evidence from randomized trials to support the use of inactivated flu vaccines in healthy children. They say their results are in line with those of three other randomized trials of trivalent inactivated vaccines: 43% efficacy in children six months to six years old, 51% in children 18 months to six years, and 56% in children three to nine years (H1N1 only).

This randomized study provides additional evidence of the efficacy of QIV against influenza as confirmed by PCR, the researchers say. They stress the vaccine's efficacy against moderate and severe cases, saying the greatest value of vaccination is in preventing such cases.

Lance D. Presser has a PhD in Microbiology and Immunology and currently is a Public Health Laboratorian

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