PTAB

IPR2019-00431

Clear Vu Lighting LLC v. University Of Strathclyde

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1. Case Identification

2. Patent Overview

  • Title: Inactivation of Gram-Positive Bacteria
  • Brief Description: The ’706 patent is directed to methods and systems for disinfecting air and non-living surfaces by inactivating pathogenic Gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA). The claimed invention operates by exposing the bacteria to visible light within a specific wavelength range of 400-420 nm, allegedly without using an externally applied photosensitizer.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1 and 3 under 35 U.S.C. §102

  • Prior Art Relied Upon: Nitzan (a 2004 journal article, "ALA induced photodynamic effects on Gram positive and negative bacteria").
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Nitzan disclosed every element of independent claims 1 and 3. Nitzan described experiments that inactivated MRSA, a specifically claimed bacterium, by illuminating it on non-living plastic dishes (fulfilling the “contact surfaces” and “non-living” limitations) using light with a wavelength of 407-420 nm. This light source falls entirely within the claimed 400-420 nm range and the method was performed outside the human body. Petitioner contended Nitzan’s method did not use an exogenous photosensitizer, as Nitzan relied on the excitation of endogenous porphyrins naturally present in the bacteria, thus meeting the “without using a photosensitizer” limitation under Petitioner’s proposed construction.
    • Key Aspects: Petitioner asserted that Nitzan's use of aminolevulinic acid (ALA) to induce higher levels of endogenous porphyrin production did not constitute using a photosensitizer, as ALA itself is a precursor in a metabolic pathway, not a light-reactive substance that initiates the inactivation.

Ground 2: Obviousness of Claims 1 and 3 under 35 U.S.C. §103

  • Prior Art Relied Upon: Ashkenazi (a 2002 journal article, "Eradication of Propionibacterium acnes by its endogenic porphyrins...") and Nitzan.

  • Core Argument for this Ground:

    • Prior Art Mapping: Ashkenazi taught the inactivation of P. acnes (a Gram-positive bacterium) using 407-420 nm light without adding any external precursors, demonstrating the viability of the method in the complete absence of exogenous agents. Nitzan established that the same light wavelengths were effective for inactivating the claimed MRSA bacterium.
    • Motivation to Combine: A person of ordinary skill in the art (POSA), seeking alternative approaches to combat antibiotic-resistant bacteria like MRSA, would have been motivated to apply Ashkenazi's established technique (inactivation without any added agents) to the specific, clinically significant bacterium taught by Nitzan (MRSA). The fact that some of the same researchers worked on both studies underscored the predictability of this combination.
    • Expectation of Success: A POSA would have had a high expectation of success. Both references teach the same underlying mechanism (excitation of endogenous porphyrins) for inactivating Gram-positive bacteria with the same light spectrum. Combining the teachings would amount to a simple, predictable substitution of one Gram-positive bacterium (MRSA) for another (P. acnes) in a known process to achieve an expected result. Petitioner argued that minor differences in experimental parameters, such as light dosage, would not detract from this expectation, as a POSA would understand how to optimize such known variables.

  • Additional Grounds: Petitioner asserted additional obviousness challenges against dependent claims 2 and 4. These grounds argued it would have been obvious to modify the methods of Nitzan (Ground B) or the combined Ashkenazi/Nitzan method (Ground D) by using a specific wavelength of 405 nm. The motivation was based on a third reference, Jones (Application # 2005/0055070), which taught that 405 nm is an optimal wavelength for activating the specific porphyrins responsible for bacterial inactivation.

4. Key Claim Construction Positions

  • "without using a photosensitizer": This term was central to the petition. Petitioner argued it should be construed to mean "without applying an exogenous photosensitizer" (e.g., an external dye). Petitioner contended that the patent’s specification and prosecution history distinguish the invention from prior art that required adding external agents, while implicitly relying on the action of endogenous photosensitizers (porphyrins) naturally produced by the bacteria. This construction allows the prior art, which also relies on endogenous porphyrins, to meet the claim limitation.
  • "inactivating": Petitioner asserted this term is defined by the patent as killing or damaging bacteria to reduce or inhibit replication. This does not require complete sterilization, and therefore, the significant reduction in bacterial viability shown in the prior art references meets the "inactivating" and "disinfecting" limitations.
  • "means for exposing" (Claim 3): Petitioner argued this is a means-plus-function limitation under §112, with the patent disclosing the corresponding structure as a Xenon lamp or an LED array. Petitioner contended that the lamp used in the Nitzan reference was an equivalent structure that performed the identical function, thus satisfying this limitation.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-4 of Patent 9,839,706 as unpatentable.