Ownership Submission
FORM 3
 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
  Merck & Co., Inc.
 2. Date of Event Requiring Statement (Month/Day/Year)
07/14/2015		 3. Issuer Name and Ticker or Trading Symbol
OPGEN INC [OPGN]
(Last)
(First)
(Middle)
2000 GALLOPING HILL ROAD		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

KENILWORTH, NJ 07033		 6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security
(Instr. 4)		 2. Amount of Securities Beneficially Owned
(Instr. 4)		 3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)		 4. Nature of Indirect Beneficial Ownership
(Instr. 5)
Common Stock 1,479,022
I
See Footnote (1)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)		 2. Date Exercisable and Expiration Date
(Month/Day/Year)		 3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)		 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)		 6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Merck & Co., Inc.
2000 GALLOPING HILL ROAD
KENILWORTH, NJ 07033		     X    
Merck Sharp & Dohme Corp.
ONE MERCK DRIVE
WHITEHOUSE STATION, NJ 08889		     X    
Merck Global Health Innovation Fund, LLC
ONE MERCK DRIVE
WHITEHOUSE STATION, NJ 08889		     X    

Signatures

/s/ Katie Fedosz as Attorney-In-Fact 07/23/2015
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) These shares are owned directly by Merck Global Health Innovation Fund, LLC, which is a wholly owned subsidiary of Merck Sharp & Dohme Corp. ("MSD"), which is a wholly owned subsidiary of Merck &Co, Inc. ("Merck"). MSD and Merck are indirect beneficial owners of the reported securities.
 
Remarks:
Ms. Katie Fedosz is signing as Attorney-in-Fact pursuant to power of attorney dated July 23, 2015 granted by each Reporting Person, a copy of which is filed as an exhibit and incorporated herein by reference.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, See Instruction 6 for procedure.

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